Command and Programming Manual

Rev 1.7.1

Applicable to CH0x0/HI02/04/05/06/14/50/90/70 series (shared programming interface)

This manual is based on firmware version: 1.7.1

Actual feature availability depends on the specific product model, firmware version, and delivered configuration.

Manual Version Notes (Important)

Because there are subtle differences in commands, performance, and features between firmware versions, please choose the corresponding user manual based on the firmware version of your product:

Applicable firmware version	Matching user manual version	Download link
1.7.1	1.7.1	This manual
1.5.5 - 1.7.0	1.3.0	imu_cum_cn_150_170.pdf

Module Configuration Overview

Before using the product, please read this chapter carefully and determine whether user configuration is required based on your actual use case.

Operating Mode Configuration - AHRS / 9-Axis Mode

⚠️ Warning In robotic applications and indoor environments, the AHRS (9-axis) mode is easily disturbed by ambient magnetic fields or magnetic fields generated by motors, which can introduce errors into the heading angle.

In open environments without magnetic interference (e.g., outdoor UAV operations), magnetometer-aided mode may be used. Before use, you need to:

Configure the module to magnetometer-aided mode;
Perform magnetic calibration (see the "Magnetic Calibration" chapter).

Synchronous Input - SYNC_IN / PPS

The module's synchronization-related features rely on the SYNC_IN/PPS pin, mainly including the following two categories:

SYNC_IN data trigger
PPS (pulse-per-second) input for UTC time synchronization

SYNC_IN Data Trigger

Some products provide a synchronization input pin (SYNC_IN/PPS) that can be used to trigger data output by external pulses. Leave the pin floating or grounded when not in use. Working principle: when the output protocol is configured to the ONMARK trigger mode (see the LOG command), the module outputs one frame of data each time a rising edge is detected on the SYNC_IN pin.

Application scenario: mainly used to receive high-precision pulses generated by the host controller or an external clock source to trigger synchronous IMU data output.

PPS Standard Pulse Input

This function uses the (SYNC_IN/PPS) pin to receive the GPS PPS pulse signal, combined with time messages received from the UART, to provide precise UTC time synchronization for the IMU. When the module detects a valid PPS rising edge and receives a matching time message via the UART, its internal clock automatically aligns to UTC integer seconds.

1. Timing and Signal Requirements

To ensure reliable time synchronization, the PPS pulse and the UART time message must satisfy the following timing relationship:

mermaid

gantt
    title PPS and UART time-message timing (t0-t3)
    dateFormat  X
    axisFormat  %s

    section SYNC_IN/PPS
    t1 (pulse width) :active, p1, 0, 50
    t0 (period) :p2, 0, 1000

    section UART time message
    t3 (delay) :crit, d1, 0, 150
    t2 (transmission time) :done, r1, 150, 250

Parameter description:

Parameter	Description	Valid range	Recommended value
t0	Interval between two adjacent PPS rising edges	990 ms ~ 1010 ms	1000 ms
t1	PPS high-level duration (pulse width)	1 ms ~ 100 ms	10 ms ~ 50 ms
t2	Transmission time of the time message	Depends on baud rate	-
t3	Delay between start of the time message and the PPS rising edge	-200 ms ~ +200 ms	0 ms ~ 100 ms

⚠️ Core requirement: The time message used for synchronization must be sent within 200 ms before or after the PPS rising edge (i.e., $| t 3 | \leq 200 m s$ ); otherwise the IMU will not be able to match UTC time correctly.

2. Hardware and Interface Requirements

Hardware pin (SYNC_IN/PPS):
- Trigger edge: rising edge;
- Logic level: high level ≤ 5 V (TTL/CMOS compatible);
UART data (RX):
- Message rate: 1~10 Hz (recommended: 1 Hz);
- Baud rate: must exactly match the IMU UART setting;
- Supported protocols: only standard NMEA RMC or GGA sentences.

3. Time Message Example (GPRMC)

text

$GPRMC,235952.00,A,3112.5000,N,12127.5000,E,0.0,0.0,141125,0.0,E,A*3B

After time synchronization, the timestamp (uint32_t) in each data frame indicates the milliseconds elapsed since UTC 00:00:00 of the current day.

Parameter	Value
Range	0~86,399,999 ms
Range of time	00:00:00.000 to 23:59:59.999
Resolution	1 ms

Timestamp conversion examples and C code:

Timestamp (ms)	UTC time
0	00:00:00.000
3661000	01:01:01.000
43200000	12:00:00.000
86399999	23:59:59.999

// Time conversion formula:
// Hours = timestamp / 3600000
// Minutes = (timestamp % 3600000) / 60000
// Seconds = (timestamp % 60000) / 1000
// Milliseconds = timestamp % 1000

void ms_to_utc_time(uint32_t total_ms, char *utc_time, int buf_size)
{
    // Calculate hours, minutes, seconds and milliseconds
    uint32_t total_seconds = total_ms / 1000;
    uint32_t ms_part = total_ms % 1000;

    uint8_t hours = (total_seconds / 3600) % 24;
    uint8_t minutes = (total_seconds % 3600) / 60;
    uint8_t seconds = total_seconds % 60;

    // Format as hh:mm:ss.sss
    snprintf(utc_time, buf_size, "%02d:%02d:%02d.%03d",
             hours, minutes, seconds, ms_part);
}

📝 Notes
The timestamp does not contain date information; it only represents UTC time of the current day (milliseconds since 00:00:00).
It does not include time-zone information and is interpreted as UTC+0; for local time, the host should add the time-zone offset.

Synchronous Output - SOUT

SOUT is the module's synchronous output pin. It stays low (idle) when no data is being transmitted; before a frame starts to transmit, a high pulse is emitted, and data transmission begins immediately after the falling edge of the pulse.

The SOUT pin also supports frequency division, allowing the synchronization pulse to be output at a configurable divisor. This can be used to trigger lower-rate devices such as cameras for tight time synchronization. See CONFIG PMUX2 DIV in the "Module Configuration" chapter for divider configuration.

Vessel Wave-Compensated Displacement Output - Heave, Surge, Sway

This product can measure the periodic vessel motion induced by sea waves (heave, surge, sway) and provide high-precision real-time three-axis wave motion information:

Motion axis	Description	Output data
Heave	Vertical heave	Vertical displacement, vertical velocity, vertical displacement period
Surge	Longitudinal surge	Longitudinal displacement, longitudinal velocity, longitudinal displacement period
Sway	Lateral sway	Lateral displacement, lateral velocity, lateral displacement period

Application scenarios:

Vessel dynamic monitoring and attitude control
Offshore engineering motion compensation (lifting, docking)
Wave characterization and statistical analysis
Offshore platform stability analysis
Dynamic positioning (DP) system assistance

Usage Limitations

⚠️ Important limitations
Only applicable to periodic reciprocating motion.
The following situations generally cannot be measured accurately:
Motions with very long periods (>30 s)
One-directional linear motion
Step-type displacement
Zero-mean assumption: the algorithm assumes the long-term average of displacement is 0.
Initialization time: a steady 5~20 wave cycles are required for initialization to obtain correct results.
Frequency response range: typical wave periods are 3~20 s; accuracy degrades outside this range.

📝 Product compatibility Only HI7x/HI9x series products support this feature. See "Product Feature Support Matrix".

Product Feature Support Matrix

The following table provides an overview of common feature support across product families. Actual feature availability depends on the specific product model, firmware version, and delivered configuration.

Features not listed in the table do not imply they are necessarily supported or enabled by default; for a specific model, please refer to the delivery notes.

Model / Command	HI02	HI05/06	CH0x0, HI04/12/13/14	HI50	HI7x/9x
Magnetometer aiding / mag calibration	✗	✅	✅	✗	✅
User attitude calibration	✗	✅	✅	✅	✅
IO pin multiplexing (PMUX)	✗	✅	✅	✗	✗
CAN communication interface	✗	✅	✅	✅	✅
Vessel heave output	✗	✗	✗	✗	✅
Inclinometer output	✗	✗	✗	✅	✗

Module Configuration Commands (ASCII)

Module configuration uses ASCII string commands sent over the UART. Each command must end with carriage-return + line-feed \r\n (similar to AT commands).

For any operation that modifies parameters, the recommended procedure is: "Send the configuration command -> execute SAVECONFIG -> reset or power cycle -> verify again". Query-type commands and some communication-control commands may take effect immediately in the current session, but the recommended configuration flow above still applies.

📝 Configuration semantics
Whether a command takes effect immediately is specified in each command description;
For configurations that must persist, execute SAVECONFIG and then reset or power cycle to confirm;
Communication-parameter commands may switch immediately on the current interface;
Restore-type commands may automatically save and trigger a reset.

The following table lists common externally-facing configuration commands. Additional commands for compatibility, debugging, or customization purposes depend on the actual delivered configuration.

Command Overview

Command	Function	Remarks
REBOOT	Reset the module	Equivalent to a power cycle
SAVECONFIG	Save all configuration parameters	Takes effect immediately
SERIALCONFIG	Configure UART baud rate	Takes effect immediately
CONFIG	Configure module parameters and modes	Save and reset for effect
LOG	Query module info or configure output	Takes effect immediately
FRESET	Restore factory defaults	Takes effect immediately

Command Details

REBOOT

Reset the module. Execute REBOOT BL to reset into Bootloader mode. Examples: REBOOT, REBOOT BL

SAVECONFIG

Save all user configurations to flash. Example: SAVECONFIG

SERIALCONFIG

Set the current UART baud rate.

Format: SERIALCONFIG <BAUD>

Parameters:

BAUD: target baud rate. Supported values: 4800, 9600, 19200, 38400, 57600, 115200, 230400, 256000, 460800, 921600

Example:

SERIALCONFIG 115200 - set the current UART to 115200 baud

⚠️ Important This command takes effect immediately. After execution, switch to the new baud rate to continue communicating with the module.

CONFIG

Used to configure module parameters and operating modes. For any CONFIG setting that needs to persist, run SAVECONFIG after the change and confirm the result after a reset or power cycle.

Operating Mode Configuration

Operating mode configuration: 6-axis or 9-axis (magnetometer-aided) mode. Format: CONFIG ATT MODE <VAL>. The most common modes are listed below; other industry-specific or customized modes depend on the actual delivered configuration.

Examples:

CONFIG ATT MODE 0 - configure the module to VRU (6-axis) mode
CONFIG ATT MODE 1 - configure the module to AHRS (9-axis) mode
CONFIG ATT MODE 4 - humanoid robot dedicated mode

User Attitude Calibration

Used to perform attitude zero-point related operations. Format: CONFIG ATT RST <VAL>. The device must remain stationary while executing this command; otherwise large calibration errors may be introduced.

Examples:

CONFIG ATT RST 1 - Heading reset: zero the current heading angle
CONFIG ATT RST 2 - Set relative zero: zero the current Pitch and Roll angles
CONFIG ATT RST 3 - Auto-level: only valid when the device is close to horizontal. Defined as:
- If the current Pitch/Roll is close to 0° (placed horizontally right-side up), auto-calibrate to Pitch=0°, Roll=0°;
- If the current Pitch is close to 0° and Roll is close to 180° (placed horizontally upside-down), auto-calibrate to Pitch=0°, Roll=180°;
- The "close to" threshold is Pitch and Roll both less than 5°.
CONFIG ATT RST 5 - Cancel auto-level: clear relative Pitch and Roll angles and restore absolute angles

Mounting Orientation Setting

Used to modify the module's mounting orientation, such as horizontal mounting, vertical mounting, upside-down, or forward-facing installation for integrated navigation. Save and reset to confirm such settings; no need to resend at every power-up.

Format: CONFIG IMU URFR <CODE>

Parameters:

CODE: 2- to 3-digit orientation code, representing the mounting direction of the user coordinate system relative to the sensor coordinate system.
The code is written as ABC, where:
- A indicates which direction in the sensor frame the user-frame X axis points to
- B indicates which direction in the sensor frame the user-frame Y axis points to
- C indicates which direction in the sensor frame the user-frame Z axis points to
Each digit has the following meaning:

Digit	Direction
`0`	`+X`
`1`	`-X`
`2`	`+Y`
`3`	`-Y`
`4`	`+Z`
`5`	`-Z`

Notes:

24 is equivalent to 024, meaning user frame X=+X, Y=+Y, Z=+Z. For the product's default mounting, this can be understood as X points right, Y points forward, Z points up.
This command uses spaces to separate parameters. The correct form is CONFIG IMU URFR 24, not CONFIG IMU URFR=24.
The current configuration query result is displayed in the form URFR=<CODE>.
If the user coordinate system is defined as right/forward/up of the body, you can directly choose the corresponding code from the table below based on the installation orientation.

Complete configuration examples (24 valid right-handed combinations):

The table is presented in "Equivalent installation description" form (consistent with the host UI dropdown): direction of IMU X/Y/Z in Body(B).
The URFR encoding itself is still three digits ABC (with the right-handed constraint X × Y = Z); the 2-digit display value is equivalent to the 3-digit value with a leading zero (e.g., 24 = 024).

Equivalent installation description (IMU axes in Body(B))	Configuration command	Notes
`IMU X points right, IMU Y points forward, IMU Z points up`	`CONFIG IMU URFR 24`	Default horizontal mounting; full code is `024`.
`IMU X points right, IMU Y points backward, IMU Z points down`	`CONFIG IMU URFR 35`	Common upside-down mounting (rotated about X relative to default); full code is `035`.
`IMU X points right, IMU Y points down, IMU Z points forward`	`CONFIG IMU URFR 43`	Common side mounting; matches "Right + Down" in the host UI.
`IMU X points right, IMU Y points up, IMU Z points backward`	`CONFIG IMU URFR 52`	Common side mounting; matches "Right + Up" in the host UI.
`IMU X points left, IMU Y points forward, IMU Z points down`	`CONFIG IMU URFR 125`	Inverted combo with `X` reversed and `Z` pointing down.
`IMU X points left, IMU Y points backward, IMU Z points up`	`CONFIG IMU URFR 134`	Both `X/Y` reversed with `Z` up; common when orientation is reversed.
`IMU X points left, IMU Y points up, IMU Z points forward`	`CONFIG IMU URFR 142`	Left-facing vertical mounting with `Y` pointing up.
`IMU X points left, IMU Y points down, IMU Z points backward`	`CONFIG IMU URFR 153`	Left-facing vertical mounting with `Y` pointing down.
`IMU X points forward, IMU Y points right, IMU Z points down`	`CONFIG IMU URFR 205`	Forward-facing mounting, suitable when `X` is aligned with the vehicle heading.
`IMU X points backward, IMU Y points right, IMU Z points up`	`CONFIG IMU URFR 214`	Backward-facing mounting; `Y` still points right.
`IMU X points up, IMU Y points right, IMU Z points forward`	`CONFIG IMU URFR 240`	Vertical mounting with `X` up and `Y` right.
`IMU X points down, IMU Y points right, IMU Z points backward`	`CONFIG IMU URFR 251`	Vertical mounting with `X` down and `Y` right.
`IMU X points forward, IMU Y points left, IMU Z points up`	`CONFIG IMU URFR 304`	Forward-facing mounting with `Y` changed to left.
`IMU X points backward, IMU Y points left, IMU Z points down`	`CONFIG IMU URFR 315`	Backward-facing upside-down mounting; both `X/Y` reversed.
`IMU X points down, IMU Y points left, IMU Z points forward`	`CONFIG IMU URFR 341`	Left-facing vertical mounting with `X` down.
`IMU X points up, IMU Y points left, IMU Z points backward`	`CONFIG IMU URFR 350`	Left-facing vertical mounting with `X` up.
`IMU X points forward, IMU Y points up, IMU Z points right`	`CONFIG IMU URFR 402`	Forward-facing vertical mounting with `Y` up and `Z` right.
`IMU X points backward, IMU Y points down, IMU Z points right`	`CONFIG IMU URFR 413`	Backward-facing vertical mounting with `Y` down and `Z` right.
`IMU X points down, IMU Y points forward, IMU Z points right`	`CONFIG IMU URFR 421`	Vertical mounting with `X` down and `Z` right.
`IMU X points up, IMU Y points backward, IMU Z points right`	`CONFIG IMU URFR 430`	Vertical mounting with `X` up and `Z` right.
`IMU X points forward, IMU Y points down, IMU Z points left`	`CONFIG IMU URFR 503`	Forward-facing vertical mounting with `Y` down and `Z` left.
`IMU X points backward, IMU Y points up, IMU Z points left`	`CONFIG IMU URFR 512`	Backward-facing vertical mounting with `Y` up and `Z` left.
`IMU X points up, IMU Y points forward, IMU Z points left`	`CONFIG IMU URFR 520`	Common vertical mounting with `X` up and `Z` left.
`IMU X points down, IMU Y points backward, IMU Z points left`	`CONFIG IMU URFR 531`	Common vertical mounting with `X` down and `Z` left.

Multi-Function IO Multiplexing Configuration

The module provides multiple multi-function pins (IOx). Each IO pin has a default multiplexing function and can also be remapped to other functions via software. Format: CONFIG <PMUX> <IO>.

Parameters:

PMUX: multiplexing function ID (PMUX1 ~ PMUX3)
IO: target pin ID (IO1 ~ IO5)

Function	Name	Dir	Description	Default IO
PMUX1	SIN/PPS	I	Sync pulse input (SIN/PPS): input pin, see "Synchronous Input/Output"	IO1
PMUX2	SOUT	O	Low when no data is being transmitted (idle); before a frame starts to be sent, a high pulse is emitted, and data transmission begins immediately after the falling edge of the pulse	IO2
PMUX3	LED	O	Operating-status indicator output	IO5

Examples:

CONFIG PMUX3 IO2 - assign IO2 to the LED (PMUX3) function
CONFIG PMUX2 IO1 - assign IO1 to the sync output (PMUX2) function

📝 Note Not all IO pins are physically exposed on every product. See the corresponding product user manual for detailed hardware resources.

SOUT (PMUX2) Sync-Output Divider

The SOUT sync output supports frequency division, which can be used to trigger lower-rate fusion sensors such as cameras. Format: CONFIG PMUX2 DIV <N>.

Parameters:

N: divider, range 1~1000, default 1 (no division)

Example:

CONFIG PMUX2 DIV 5 - set the SOUT divider to 5. If the data output rate is 100 Hz, the SOUT pulse output frequency is 20 Hz.

Magnetic Calibration

Start a manual magnetic calibration: CONFIG MCAL START. After issuing this command, the module starts the calibration procedure and completes it automatically based on the spatial magnetic-field distribution; no explicit stop command is needed. During calibration, slowly rotate the module in place and ensure that any objects rigidly attached to it (PCB, housing, robot, etc.) maintain their relative positions. See the "Magnetic Calibration" chapter for details.

After issuing the start command, you can query calibration status with LOG MCAL STAT. Example response:

STAT=1
PROGRESS=8
OK

STAT: current magnetic calibration state. 0 = idle, 1 = calibrating, 3 = calibration complete, 4 = calibration failed
PROGRESS: current calibration progress, range 0~100

📝 Important The magnetic calibration command requires firmware version ≥ 1.7.0.

Coordinate System Definition

The module uses the East-North-Up (ENU) coordinate system by default. You can switch the world coordinate system using the following commands:

CONFIG IMU COORD 0 - set the world frame to East-North-Up (ENU)
CONFIG IMU COORD 4 - set the world frame to North-West-Up (NWU)

User-Level Gyroscope Calibration

This command is used to manually calibrate the gyroscope Z-axis scale factor. When properly executed, it can improve heading accuracy (after calibration, the scale-factor error is within 0.1%). Suitable for AGVs, large horizontally-moving robots, and other applications with high long-term heading-accuracy requirements. Format: CONFIG USRCAL START <ANGLE>.

Parameters:

ANGLE: calibration angle, range 720~1800° (2~5 turns). More turns reduce statistical error, but uniform rotation speed must be maintained.

Examples:

Preparation: place the module (together with the rigidly attached platform such as a robot) on a flat horizontal surface, ensure stable ambient temperature, and avoid strong vibration.
Send the start command: e.g., CONFIG USRCAL START 720 - start 720° (2 turns) calibration.
Perform the calibration motion: rotate horizontally by the angle set in <ANGLE> at 20~100 deg/s (about 5~20 s per turn). The rotation direction can be either clockwise or counterclockwise. Maintain uniform speed throughout the rotation; avoid pauses, sudden acceleration, or deceleration.
Send the stop command: when the rotation is complete and the actual rotation angle is within ±5° of the <ANGLE> setpoint, send CONFIG USRCAL STOP to finish the calibration. The module returns OK on success or ERR on failure.

Common causes of calibration failure:

Failure cause	Description
Non-standard rotation	Ensure the module is placed horizontally and stably
Improper operation	Rotation too fast or too slow, mid-way pauses
Environmental disturbance	Avoid operating near vibrating equipment, e.g., excessive motor vibration
Errors persist or worsen after calibration	Most likely due to non-standard rotation. Calibration is a precise process: if the specified rotation is 720° but the actual rotation is 725°, the scale factor will be erroneously calibrated as 5/720 = 0.6%, far exceeding the factory accuracy

LOG

Enable/Disable Data Output

LOG ENABLE - globally enable data frame output
LOG DISABLE - globally disable data frame output

Module Version Information

LOG VERSION - query and print firmware version information

Display UART Configuration

LOG COMCONFIG - print UART and output protocol configuration

Set Output Frame Type and Rate

Format: LOG <MSG> <TYPE> <VALUE>

Parameters:

MSG: data frame type. Common types include HI91, HI81, HI83, GGA, RMC, SXT, etc. Available types depend on the specific product and current UART configuration.
TYPE: output trigger mode, supports ONTIME (periodic output) and ONMARK (sync-pulse trigger or software trigger).
VALUE: when TYPE=ONTIME, the output period in seconds. Range: 0.001 (1 kHz) ~ 1 (1 Hz); 0 disables periodic output. When TYPE=ONMARK, 1 means trigger on SYNC_IN/PPS pulse, and ONCE triggers one output manually.

Examples:

LOG HI91 ONTIME 0.01 - set the HI91 output period on the current UART to 0.01 s (100 Hz)
LOG HI91 ONTIME 0.05 - set the HI91 output period on the current UART to 0.05 s (20 Hz)
LOG HI91 ONTIME 0 - disable HI91 output
LOG HI91 ONMARK 1 - configure the HI91 frame on the current UART to be triggered by the SYNC_IN/PPS pin
LOG HI91 ONMARK ONCE - trigger one HI91 output manually (same effect as one SYNC_IN/PPS pulse)

HI83 Variable-Length Frame Configuration

HI83 is a variable-length binary output frame, suitable for applications that need to simultaneously output IMU, attitude, time, GNSS, or integrated navigation data while controlling frame length on demand. The HI83 payload is determined by data_bitmap: each bit of data_bitmap corresponds to one data segment; setting the bit to 1 enables that segment, and 0 disables it. The data segments are arranged in the frame from low bit to high bit.

Bitmap configuration format: LOG HI83 MAP <BITMAP>

<BITMAP> can be expressed in hex or decimal, e.g., 0x000000FF;
For the meaning of each bit, see the "Variable-Length Protocol (HI83)" section below;
The default HI83 bitmap is 0x000000FF.

Common configuration examples:

Command	Description
`LOG HI83 MAP 0x000000FF`	Default HI83 fields: acceleration, angular velocity, magnetic field, Euler angles, quaternion, system time, UTC, barometric pressure
`LOG HI83 MAP 0x0000001F`	IMU + basic attitude: acceleration, angular velocity, magnetic field, Euler angles, quaternion
`LOG HI83 ONTIME 0.01`	Set the `HI83` output period on the current UART to `0.01 s` (100 Hz)
`LOG HI83 ONTIME 0`	Disable periodic `HI83` output on the current UART

⚠️ Baud rate notes When the output rate is high (e.g., 500 Hz), the default 115200 baud rate may not provide sufficient bandwidth. In that case, increase the module baud rate to a higher value (e.g., 921600) to ensure stable data output.

FRESET

Restore the module's default user configuration. After execution, the module automatically saves and resets — use with caution. Some calibration-related parameters may be retained, depending on current firmware behavior. Example: FRESET

RS-232/TTL/USB Data Protocol (Binary)

RS-232, UART-TTL, and USB (virtual COM) are stream-style serial interfaces that support Hipnuc's proprietary binary protocol.

Data Frame Format

Field	Value	Length (bytes)	Description
SOF	5A A5	2	Start-of-frame sync word
LEN	1-4096	2	Payload length, LSB first (does not include header, type, length, or CRC fields)
CRC	-	2	16-bit CRC over the header, length, and payload (excludes the CRC field itself)
Payload	-	1-4096	Frame payload, composed of one or more sub-packets. Each sub-packet has a tag and data part, where the tag determines the data type and length.

Factory Default Output

Default output: floating-point IMU data frame (HI91).

Payload Content

Floating-Point IMU Data Frame (HI91)

The payload is 76 bytes and includes module ID, temperature, raw IMU data, magnetic field, barometric pressure, and fused attitude data.

Offset	Name	Type	Size (bytes)	Unit	Scale	Description
0	tag	uint8_t	1	-	-	Data tag: `0x91`
1	main_status	uint16_t	2	-	-	Status word, see `MAIN_STATUS` description
3	temperature	int8_t	1	°C	1	Module average temperature
4	air_pressure	float	4	Pa	1	Barometric pressure
8	system_time	uint32_t	4	ms	1	When GPS time is not synchronized, this field is a local timestamp (milliseconds since power-up); when GPS time is synchronized, this field is aligned to UTC milliseconds of the current day
12	acc_b	float	4×3	G	1	Factory-calibrated acceleration, XYZ order. 1 G = 1× standard gravity (~9.8 m/s²)
24	gyr_b	float	4×3	deg/s	1	Factory-calibrated angular velocity, XYZ order
36	mag_b	float	4×3	μT	1	Magnetic field strength, XYZ order
48	roll	float	4	deg	1	Roll angle
52	pitch	float	4	deg	1	Pitch angle
56	yaw	float	4	deg	1	Heading angle
60	quat	float	4×4	-	-	Node quaternion set, WXYZ order

Variable-Length Protocol (HI83)

The data carried in this protocol is configurable; different combinations can be output by data_bitmap, and the frame size changes accordingly.

Offset	Name	Type	Size (bytes)	Unit	Scale	Description
0	tag	uint8_t	1	-	-	Data tag: `0x83`
1	main_status	uint16_t	2	-	-	Status word, see `MAIN_STATUS` description
3	ins_status	uint8_t	1	-	-	Integrated navigation solution status (only for integrated-navigation products): 0: Solution invalid - no GNSS info, cannot initialize position 1: Aligning - position initialized, but speed is required to complete the integrated-navigation filter initialization to enter the integrated-navigation state 3: Integrated navigation - currently in integrated-navigation state 6: Inertial dead-reckoning - currently in integrated-navigation state but GNSS is lost; pure-inertial mode (tunnel, parking garage, etc.)
4	data_bitmap	uint32_t	4	-	-	Bitmap of carried data segments, configurable. Each bit corresponds to one data type; segments are arranged from the lowest bit to the highest
8	-	-	1-512	-	-	Subsequent payload defined by `data_bitmap`.

data_bitmap Bits and Data Segments

data_bitmap bit	Name	Type	Size	Unit	Scale	Description
0	acc_b	float	4x3	m/s^(2)	1	IMU body-frame, factory-calibrated acceleration, order: XYZ
1	gyr_b	float	4x3	rad/s	1	IMU body-frame, factory-calibrated angular velocity, order: XYZ
2	mag_b	float	4x3	μT	1	IMU body-frame, calibrated magnetic field, order: XYZ
3	rpy	float	4x3	deg	1	Attitude angles (Euler angles), order: roll, range: -180 - 180 pitch, range: -90 - 90 yaw, range: -180 - 180, counterclockwise positive
4	quat	float	4x4	-	1	Node quaternion set, WXYZ order
5	system_time_us	uint64_t	8	us	1	Local high-resolution timestamp, microseconds elapsed since power-up, incrementing by 1 every 1 us
6	utc	-	8	-	-	UTC time, 8 bytes total: year: 1 byte, e.g., 24 represents 2024 month: 1 byte day: 1 byte hour: 1 byte minute: 1 byte seconds: 2 bytes, unit 1 ms, e.g., 12 s is encoded as 12000 reserved: 1 byte
7	air_pressure	float	4	Pa	1	Barometric pressure
8	temperature	float	4	℃	1	Module average temperature
9	inclination	float	4x3	deg	1	Inclinometer output, order: about X axis, about Y axis, about Z axis
10	heave_surge_sway	float	4x3	m	1	Vessel heave-surge-sway displacement, order: heave, surge, sway
11	heave_surge_sway_frq	float	4x3	Hz	1	Vessel heave-surge-sway frequency, order: heave, surge, sway
12	vel_enu	float	4x3	m/s	1	East-North-Up velocity in the navigation frame, integrated-navigation output
13	acc_enu	float	4x3	m/s^(2)	1	East-North-Up acceleration in the navigation frame, integrated-navigation output
14	ins_lon_lat_msl	double	8x3	-	1	Fused longitude/latitude from integrated navigation, order: longitude (deg), latitude (deg), MSL altitude (m)
15	gnss_quality_nv	-	4	-	-	GNSS solution status group, 4 bytes: solq_pos: 1 byte, position solution status nv_pos: 1 byte, number of satellites used for position solq_heading: 1 byte, heading solution status nv_heading: 1 byte, number of satellites used for heading
16	od_speed	float	4	m/s	-	External odometer sensor speed
17	undulation	float	4	m		Geoid undulation
18	diff_age	float	4	s		RTK differential age
19	node_info	-	4	-		Device version and ID: `node_id`: 1 byte, node ID identical to CAN ID, range `1~127` reserved: 3 bytes
20-24						Reserved
25	event_counter	uint32_t	4x16	-	1	Internal measurement event counters. Common order: gravity, mag, gnss_pos, gnss_vel, dual_heading, nhc, zupt, zaru, zihr, od; the rest are reserved
26	kf_acc_bias	float	4x3	m/s^(2)	1	Accelerometer bias estimated by the integrated-navigation KF, order: XYZ
27	kf_gyr_bias	float	4x3	rad/s	1	Gyroscope bias estimated by the integrated-navigation KF, order: XYZ
28	gnss_std	float	4x3	-	1	GNSS accuracy, order: position standard-deviation norm, velocity standard-deviation norm, reserved
29	gnss_heading_info	float	4x3	-	1	Dual-antenna GNSS heading info, order: baseline length (m), pitch (deg), heading (deg)
30	gnss_lon_lat_msl	double	8x3	-	1	Raw GNSS longitude/latitude/altitude, order: longitude (deg), latitude (deg), MSL altitude (m)
31	gnss_vel	float	4x3	m/s	1	GNSS East-North-Up velocity, order: E, N, U

MAIN_STATUS Status Word Description

Bit	Name	Description
0-2	Reserved	-
3	WB_CONV	Bias convergence alarm. 1: current bias estimation accuracy is poor; recommended to keep the module still for 3~5 s to improve heading accuracy. 0: bias estimate has converged well.
4	MAG_DIST	Magnetic anomaly alarm. 1: magnetic interference detected, or the magnetometer is not calibrated, or the hard-magnetic environment has changed; heading error may be large in 9-axis mode. 0: magnetic environment is good and the heading has converged, or the system is in 6-axis mode.
5	ACC_SAT	Accelerometer range saturation alarm. 1: accelerometer range saturation detected currently or within the last 2 s. 0: no saturation detected at present, and no saturation event for the last continuous 2 s.
6	GYR_SAT	Gyroscope range saturation alarm. 1: gyroscope range saturation detected currently or within the last 2 s. 0: no saturation detected at present, and no saturation event for the last continuous 2 s.
7	ATT_CONV	Attitude accuracy indicator. 1: current attitude accuracy is poor (the AHRS attitude KF covariance is large); keep the module still for a moment to allow attitude accuracy to recover. 0: attitude accuracy is normal.
8-9	Reserved	-
10	MAG_AIDING	Magnetometer aiding flag. 1: magnetometer is involved in heading computation (9-axis mode). 0: magnetometer is not involved in heading computation (6-axis mode).
11	UTC_SYNCED	Time-sync flag. 1: time sync is not complete and `system_time` is local time; 0: UTC time sync is complete and `system_time` in HI91 is aligned to UTC milliseconds of the current day.
12	SOUT_PULSE	SOUT pulse output flag, used to time-synchronize with low-rate sensors (camera, LiDAR, etc.). 1: this data frame corresponds to an SOUT pulse output; 0: this data frame does not correspond to an SOUT pulse output.
13-15	Reserved	-

📝 Compatibility The MAIN_STATUS status word is only available on firmware versions ≥ 1.7.0.

CRC Verification

CRC uses the CRC-16/CCITT polynomial. Example C implementation:

/*
	currectCrc: previous crc value, set 0 if it's first section
	src: source stream data
	lengthInBytes: length
*/
static void crc16_update(uint16_t *currectCrc, const uint8_t *src, uint32_t lengthInBytes)
{
    uint32_t crc = *currectCrc;
    uint32_t j;
    for (j=0; j < lengthInBytes; ++j)
    {
        uint32_t i;
        uint32_t byte = src[j];
        crc ^= byte << 8;
        for (i = 0; i < 8; ++i)
        {
            uint32_t temp = crc << 1;
            if (crc & 0x8000)
            {
                temp ^= 0x1021;
            }
            crc = temp;
        }
    }
    *currectCrc = crc;
}

Data Frame Example (HI91)

A sample HI91 frame captured by a serial terminal contains 82 bytes in total: the first 6 bytes are the header, length, and CRC; the remaining 76 bytes are the payload. Assume the data is received into a C array buf as shown below:

5A A5 4C 00 14 BB 91 08 15 23 09 A2 C4 47 08 15 1C 00 CC E8 61 BE 9A 35 56 3E 65 EA 72 3F 31 D0 7C BD 75 DD C5 BB 6B D7 24 BC 89 88 FC 40 01 00 6A 41 AB 2A 70 C2 96 D4 50 41 ED 03 43 41 41 F4 F4 C2 CC CA F8 BE 73 6A 19 BE F0 00 1C 3D 8D 37 5C 3F

Parsing table:

Field name	Type	Raw value	Parsed value	Description
Header	-	5A A5	-	Frame header
Payload length	-	4C 00	0x004C = 76	Payload length = 76 bytes
CRC	-	14 BB	0xBB14	CRC
tag	-	91	0x91	`0x91` sub-packet tag (payload starts here)
main_status	uint16_t	08 15	0x1508	Status word
temperature	int8_t	23	0x23 = 35	Temperature, °C
air_pressure	float	09 A2 C4 47	100676	Barometric pressure, Pa
system_time	uint32_t	08 15 1C 00	0x001C1508 = 1840392	Timestamp, ms
acc_b_x	float	CC E8 61 BE	-0.220615	X-axis acceleration, G
acc_b_y	float	9A 35 56 3E	0.209189	Y-axis acceleration, G
acc_b_z	float	65 EA 72 3F	0.948889	Z-axis acceleration, G
gyr_b_x	float	31 D0 7C BD	-0.061722	X-axis angular velocity, deg/s
gyr_b_y	float	75 DD C5 BB	-0.00603836	Y-axis angular velocity, deg/s
gyr_b_z	float	6B D7 24 BC	-0.0100611	Z-axis angular velocity, deg/s
mag_b_x	float	89 88 FC 40	7.89167	X-axis magnetic field, μT
mag_b_y	float	01 00 6A 41	14.625	Y-axis magnetic field, μT
mag_b_z	float	AB 2A 70 C2	-60.0417	Z-axis magnetic field, μT
roll	float	96 D4 50 41	13.0519	Roll, deg
pitch	float	ED 03 43 41	12.1885	Pitch, deg
yaw	float	41 F4 F4 C2	-122.477	Heading, deg
q_w	float	CC CA F8 BE	-0.485922	Quaternion W
q_x	float	73 6A 19 BE	-0.14982	Quaternion X
q_y	float	F0 00 1C 3D	0.0380868	Quaternion Y
q_z	float	8D 37 5C 3F	0.860223	Quaternion Z

C Parsing Code Example (HI91)

The following snippets show common C parsing fragments:

CRC Check

int16_t payload_len;
uint16_t crc;
crc = 0;
payload_len = buf[2] + (buf[3] << 8);

/* Calculate 5A A5 and LEN field crc */
crc16_update(&crc, buf, 4);

/* Calculate payload crc */
crc16_update(&crc, buf + 6, payload_len);

The computed CRC value is 0xBB14, identical to the CRC field in the frame, so the CRC check passes.

Define Receive Data Structure

Starting from 0x91 is the sub-packet payload. The following gives an example data structure and common conversion macros:

#include "stdio.h"
#include "string.h"

/* Common type conversion */
#define U1(p) (*((uint8_t *)(p)))
#define I1(p) (*((int8_t  *)(p)))
#define I2(p) (*((int16_t  *)(p)))

static uint16_t U2(uint8_t *p) {uint16_t u; memcpy(&u,p,2); return u;}
static uint32_t U4(uint8_t *p) {uint32_t u; memcpy(&u,p,4); return u;}
static int32_t  I4(uint8_t *p) {int32_t  u; memcpy(&u,p,4); return u;}
static float    R4(uint8_t *p) {float    r; memcpy(&r,p,4); return r;}

typedef struct
{
    uint8_t     tag;              /* Item tag: 0x91        */
    float       acc[3];           /* Acceleration          */
    float       gyr[3];           /* Angular velocity      */
    float       mag[3];           /* Magnetic field        */
    float       eul[3];           /* Attitude: Euler angle */
    float       quat[4];          /* Attitude: quaternion  */
    float       pressure;         /* Air pressure          */
    uint32_t    timestamp;        /* Timestamp             */
}imu_data_t;

Receive Data

Starting at buf[6]=0x91 is the payload:

imu_data_t i0x91 = {0};
int offset = 6; /* Payload start at buf[6] */

i0x91.tag =             U1(buf+offset+0);
i0x91.pressure =        R4(buf+offset+4);
i0x91.timestamp =       U4(buf+offset+8);
i0x91.acc[0] =          R4(buf+offset+12);
i0x91.acc[1] =          R4(buf+offset+16);
i0x91.acc[2] =          R4(buf+offset+20);
i0x91.gyr[0] =          R4(buf+offset+24);
i0x91.gyr[1] =          R4(buf+offset+28);
i0x91.gyr[2] =          R4(buf+offset+32);
i0x91.mag[0] =          R4(buf+offset+36);
i0x91.mag[1] =          R4(buf+offset+40);
i0x91.mag[2] =          R4(buf+offset+44);
i0x91.eul[0] =          R4(buf+offset+48);
i0x91.eul[1] =          R4(buf+offset+52);
i0x91.eul[2] =          R4(buf+offset+56);
i0x91.quat[0] =         R4(buf+offset+60);
i0x91.quat[1] =         R4(buf+offset+64);
i0x91.quat[2] =         R4(buf+offset+68);
i0x91.quat[3] =         R4(buf+offset+72);

Print Received Data

printf("%-16s0x%X\r\n",                 "tag:",           i0x91.tag);
printf("%-16s%8.4f %8.4f %8.4f\r\n",    "acc(G):",        i0x91.acc[0], i0x91.acc[1],  i0x91.acc[2]);
printf("%-16s%8.3f %8.3f %8.3f\r\n",    "gyr(deg/s):",    i0x91.gyr[0], i0x91.gyr[1],  i0x91.gyr[2]);
printf("%-16s%8.3f %8.3f %8.3f\r\n",    "mag(uT):",       i0x91.mag[0], i0x91.mag[1],  i0x91.mag[2]);
printf("%-16s%8.3f %8.3f %8.3f\r\n",    "eul(deg):",      i0x91.eul[0], i0x91.eul[1],  i0x91.eul[2]);
printf("%-16s%8.3f %8.3f %8.3f %8.3f\r\n",  "quat:",      i0x91.quat[0], i0x91.quat[1], i0x91.quat[2], i0x91.quat[3]);
printf("%-16s%8.3f\r\n",                    "pressure(pa):", i0x91.pressure);
printf("%-16s%d\r\n",                       "timestamp(ms):", i0x91.timestamp);

Maximum Transmission Rate

Protocol	Bytes	9600 bps	115200 bps	230400 bps	256000 bps	460800 bps	921600 bps
HI91	76	10 Hz	100 Hz	250 Hz	250 Hz	500 Hz	1000 Hz

RS-485 Output Protocol (Modbus)

Modbus is a widely used general-purpose protocol in industrial automation, and can run over RS-485 or Ethernet. Products with an RS-485 or Ethernet interface usually support Modbus; actual availability depends on the specific product model and delivered configuration.

In the current firmware, the Modbus slave is mounted on the RS-485 channel of COM1 by default. For products with multiple interfaces or customized communication mappings, refer to the actual delivered configuration.

Modbus Command Description

The RS-485 communication follows the Modbus RTU specification. Data is sent and received in registers; each register is 2 bytes, big-endian (high byte first). Standard Modbus CRC is used.

Supported function codes:

0x06 (Write Single Register): write a single register (each Modbus register is 2 bytes)
0x03 (Read Holding Registers): read one or more registers
0x50 (Custom function code): used for Modbus ID auto-assignment and similar use cases, for mass production deployment and firmware upgrades

Factory default node ID: 80 (0x50)

Data Frame Format

Read Registers (0x03)

Master sends:

Field	Value	Description
ID	1-0xFF	Modbus node ID
FUN_CODE	0x03	Function code
ADDR_H	-	Register address high 8 bits
ADDR_L	-	Register address low 8 bits
LEN_H	-	Number of registers to read, high 8 bits
LEN_L	-	Number of registers to read, low 8 bits
CRC_L	-	CRC low 8 bits
CRC_H	-	CRC high 8 bits

Slave (module) responds:

Field	Value	Description
ID	1-0xFF	Modbus node ID
FUN_CODE	0x03	Function code
LEN	-	Length of returned register data in bytes (excluding ID, FUN_CODE, LEN, CRC)
DATAH	-	Returned data high 8 bits
DATAL	-	Returned data low 8 bits
...	-	More returned data
CRC_L	-	CRC low 8 bits
CRC_H	-	CRC high 8 bits

Write Register (0x06)

Master sends:

Field	Value	Description
ID	1-0xFF	Modbus node ID
FUN_CODE	0x06	Function code
ADDR_H	-	Register address high 8 bits
ADDR_L	-	Register address low 8 bits
DATA_H	-	Data to write high 8 bits
DATA_L	-	Data to write low 8 bits
CRC_L	-	CRC low 8 bits
CRC_H	-	CRC high 8 bits

Slave responds:

Field	Value	Description
ID	1-0xFF	Modbus node ID
FUN_CODE	0x06	Function code
ADDR_H	-	Register address high 8 bits
ADDR_L	-	Register address low 8 bits
DATA_H	-	Data written high 8 bits
DATA_L	-	Data written low 8 bits
CRC_L	-	CRC low 8 bits
CRC_H	-	CRC high 8 bits

Register List

Address (Hex)	Address (Dec)	Name	Type	Function	R/W	Description
0x00	0	CTRL	u16	Control	W	See control register description
0x04	4	UART1_BAUD	u16	Baud rate	R/W	UART baud rate
0x05	5	MD_ID	u16	Modbus ID	R/W	Modbus ID, valid range: 1-128
0x06	6	HEADING_MODE	u16	Heading mode	R/W	0: 6-axis mode (relative heading, 0 at power-up). 1: 9-axis mode (mag-fused, absolute heading)
0x34	52	ACCX	i16	Acceleration X	R	Unit: G (1 G = 1× gravity), scale: 0.00048828
0x35	53	ACCY	i16	Acceleration Y	R	Unit: G (1 G = 1× gravity), scale: 0.00048828
0x36	54	ACCZ	i16	Acceleration Z	R	Unit: G (1 G = 1× gravity), scale: 0.00048828
0x37	55	GYRX	i16	Angular velocity X	R	Unit: deg/s, scale: 0.061035
0x38	56	GYRY	i16	Angular velocity Y	R	Unit: deg/s, scale: 0.061035
0x39	57	GYRZ	i16	Angular velocity Z	R	Unit: deg/s, scale: 0.061035
0x3A	58	MAGX	i16	Magnetic field X	R	Unit: μT, scale: 0.030517
0x3B	59	MAGY	i16	Magnetic field Y	R	Unit: μT, scale: 0.030517
0x3C	60	MAGZ	i16	Magnetic field Z	R	Unit: μT, scale: 0.030517
0x3D	61	R_H	i32	Roll high 16 bits	R	Unit: deg, scale: 0.001
0x3E	62	R_L	-	Roll low 16 bits	R	Unit: deg, scale: 0.001
0x3F	63	P_H	i32	Pitch high 16 bits	R	Unit: deg, scale: 0.001
0x40	64	P_L	-	Pitch low 16 bits	R	Unit: deg, scale: 0.001
0x41	65	Y_H	i32	Heading high 16 bits	R	Unit: deg, scale: 0.001
0x42	66	Y_L	-	Heading low 16 bits	R	Unit: deg, scale: 0.001
0x43	67	TEMP	i16	Temperature	R	Unit: ℃, scale: 0.01
0x44	68	PRS_H	i32	Pressure high 16 bits	R	Unit: Pa, scale: 0.01
0x45	69	PRS_L	-	Pressure low 16 bits	R	Unit: Pa, scale: 0.01
0x46	70	Q0	u16	Quaternion QW	R	Quaternion, scale: 0.0001
0x47	71	Q1	u16	Quaternion QX	R	Quaternion, scale: 0.0001
0x48	72	Q2	u16	Quaternion QY	R	Quaternion, scale: 0.0001
0x49	73	Q3	u16	Quaternion QZ	R	Quaternion, scale: 0.0001
0x4A	74	INCLI_X	i16	Inclinometer X angle	R	Dual-axis inclinometer products: X angle, ±180, unit: deg, scale: 0.011 Single-axis inclinometer products: X angle, 0-360, unit: deg, scale: 0.011
0x4B	75	INCLI_Y	i16	Inclinometer Y angle	R	Dual-axis inclinometer: Y angle, ±90, unit: deg, scale: 0.011 Single-axis inclinometer: reserved
0x4E	78	HEVAE	i16	Vessel heave	R	Vessel heave displacement output, unit: m, scale: 0.01
0x51	81	HEAVE_PERIOD	i16	Vessel heave period	R	Vessel heave displacement period, unit: s, scale: 0.001
0x70-0x77	112-119	PNAME	u16	Device name	R	Device name string in ASCII, 8 registers total
0x78	120	SW_VERSION	u16	Software version	R	Software version
0x79	121	BL_VERSION	u16	BL version	R	Bootloader version
0x7F-0x82	127-130	SN	u16	Unique serial number	R	Unique serial number, 4 registers
0xA5	165	ATT_RST	u16	Auto-level	W	3: perform one auto-level: if current pitch/roll is close to 0°,0° (placed horizontally right-side up), auto-calibrate to 0°,0°. If current pitch/roll is close to 0° or 180° (placed horizontally upside-down), auto-calibrate to 0°,180°. Suitable for robotic installations. "Close to" means both Pitch and Roll are less than 15°. 5: cancel auto-level and restore absolute angle output Other values: invalid

Control register description (register address: 0x00)

Command	Value to write
Save all configuration to Flash	0x0000
Restore factory defaults	0x0001
Reset	0x00FF

Common Configurations

📝 Note All configuration examples below use Modbus address 0x50 (factory default) as an example. If you have modified the Modbus ID, update the ID field and CRC in the message accordingly.

Save Configuration to Flash

50 06 00 00 00 00 84 4B

Restore Factory Defaults

50 06 00 00 00 01 45 8B

⚠️ Executing this command restores the module's default user configuration, then automatically saves and resets. Some calibration-related parameters may be retained.

Reset

50 06 00 00 00 FF C4 0B

Configure Baud Rate (0x04)

Target baud rate	Command (Hex) ID=`0x50` (factory default)
4800	`50 06 00 04 00 00 C5 8A`
9600	`50 06 00 04 00 01 04 4A`
19200	`50 06 00 04 00 02 44 4B`
38400	`50 06 00 04 00 03 85 8B`
57600	`50 06 00 04 00 04 C4 49`
115200	`50 06 00 04 00 05 05 89`
230400	`50 06 00 04 00 06 45 88`
460800	`50 06 00 04 00 07 84 48`
921600	`50 06 00 04 00 08 C4 4C`

Configure Node ID (0x05)

Format: [CURRENT_ID] 06 00 05 00 [NEW_ID] CRC(2 bytes)

Parameters:

CURRENT_ID: current Modbus node ID
NEW_ID: new target Modbus node ID

Examples (current node ID = 0x50):

Set NEW_ID=0x50: 50 06 00 05 00 50 94 76
Set NEW_ID=0x51: 50 06 00 05 00 51 55 B6
Set NEW_ID=0x52: 50 06 00 05 00 52 15 B7
Set NEW_ID=0x53: 50 06 00 05 00 53 D4 77

⚠️ Important Once changed, the new Modbus address takes effect immediately. The host must switch CURRENT_ID to the new node ID for subsequent communication. If you are not familiar with Modbus message construction, use a host tool to perform the configuration.

Set Mounting Orientation (0xA6)

Target mounting orientation	Command (Hex) ID=`0x50` (factory default)
Horizontal, Z-axis up (default)	`50 06 00 A6 00 18 64 62`
Rotated -90° about X (vertical mount, Y+ pointing down)	`50 06 00 A6 00 2B 24 77`
Rotated +90° about X (vertical mount, Y+ pointing up)	`50 06 00 A6 00 34 65 BF`
Rotated +90° about Y (vertical mount, X+ pointing up)	`50 06 00 A6 02 08 64 CE`
Rotated -90° about Y (vertical mount, X+ pointing down)	`50 06 00 A6 01 A5 A5 83`

Set Auto-Level (0xA5)

Start auto-level: 50 06 00 A5 00 02 15 A9
Cancel auto-level: 50 06 00 A5 00 05 54 6B

Set 6-Axis or 9-Axis Mode (0x06)

Set to 6-axis mode: 50 06 00 06 00 00 64 4A
Set to 9-axis mode: 50 06 00 06 00 01 A5 8A

Read Module Version Information (0x70-0x82)

Read product name, software version, and serial number. Request frame: 50 03 00 70 00 14 49 9F

Field	Value	Description
Modbus node ID	0x50	Modbus node ID
Function code	0x03	Read holding registers
Start address	0x0070	Product info start address
Read length	0x0014	Read 20 registers
CRC	0x9F49	-

Response frame: 50 03 28 48 49 31 34 52 32 4E 2D 34 38 35 2D 30 30 30 00 00 98 00 6B 00 00 00 00 00 00 00 00 00 00 04 7D 95 5F 8D 2A 17 08 00 00 4D 0C

Field	Data	Description
Modbus node ID	0x50	Modbus node ID
Function code	0x03	Function code
Data length	0x28	Returns 40 bytes of data; 20 registers requested, 2 bytes each
Product name	48 49...30 30	CH10x(M)
Software version	0x98	V1.52
Bootloader version	0x6B	V1.07
Serial number	047D955F8D2A1708	SN code

Read Sensor Data (0x34-0x4B)

Request frame: 50 03 00 34 00 18 09 8F

Field	Value	Description
Modbus node ID	0x50	Modbus node ID
Function code	0x03	Read holding registers
Start address	0x0034	Sensor data start address
Read length	0x0018	Read 24 registers
CRC	0x8F09	-

Response frame: 50 03 30 FF 01 03 B0 06 50 FC C9 FF 7C 00 91 01 D5 FD DB FD 27 00 00 21 FF 00 00 7F F6 FF FD 73 E7 00 00 00 00 00 00 10 A6 0D 59 DD 4E 86 A8 06 30 17 82 1E CE

Data parsing examples:

Acceleration (unit: G, where 1 G = 9.8 m/s²):

Axis	Register value (HEX)	Raw value (DEC)	Scale	Physical value
X	FF 01	-255	0.00048828	-0.1245
Y	03 B0	944	0.00048828	0.4609
Z	06 50	1616	0.00048828	0.7891

Angular velocity (unit: deg/s):

Axis	Register value (HEX)	Raw value (DEC)	Scale	Physical value
X	FC C9	-823	0.061035	-50.2318
Y	FF 7C	-132	0.061035	-8.0566
Z	00 91	145	0.061035	8.8501

Magnetic field (unit: μT):

Axis	Register value (HEX)	Raw value (DEC)	Scale	Physical value
X	01 D5	469	0.030517	14.3125
Y	FD DB	-549	0.030517	-16.7538
Z	FD 27	-729	0.030517	-22.2469

Euler angles (unit: deg):

Axis	Register value (HEX)	Raw value (DEC)	Scale	Physical value
Roll	00 00 21 FF	8703	0.001	8.703
Pitch	00 00 7F F6	32758	0.001	32.758
Yaw (heading)	FF FD 73 E7	-166937	0.001	-166.937

CAN Data Protocol (J1939)

Products with CAN output usually use the J1939 protocol by default, strictly following the SAE J1939 international standard. J1939 is a higher-layer protocol based on the CAN 2.0B extended frame format, widely used in commercial vehicles and industrial equipment. For more details, see here.

CAN Extended Frame Format

J1939 uses the CAN 2.0B extended frame format. The 29-bit identifier is structured as follows:

Bit field layout (MSB → LSB):
[28:26] Priority (P)     - priority (3 bits)
[25]    Reserved (R)     - reserved (1 bit)
[24]    Data Page (DP)   - data page (1 bit)
[23:16] PDU Format (PF)  - PDU format (8 bits)
[15:8]  PDU Specific (PS)- PDU specific (8 bits)
[7:0]   Source Address   - source address (8 bits)

Identifier formula:

CAN_ID = (Priority << 26) | (Reserved << 25) | (DataPage << 24) | (PF << 16) | (PS << 8) | SourceAddress

Byte Order (Endianness)

Important note: The J1939 protocol uses little-endian data format:

Multi-byte data: low byte first, high byte last.
Bit order: LSB (Least Significant Bit) at the low position.
Example: the 32-bit integer 0x12345678 appears in a CAN frame as: 78 56 34 12.

CANFD Support

This section describes the protocol for CANFD output. Whether a specific product supports CANFD and whether the current firmware enables it depends on the actual product model and firmware configuration.

When the product supports and enables CANFD output, the control-field baud rate of the CANFD frame is the same as classic CAN 2.0B, the FD frame data-field baud rate is typically 4 Mbps, and the data length is 64 bytes.

Protocol Parameters

Parameter	Value	Description
CAN baud rate	500 Kbps (default)	Supports 125K/250K/500K/800K/1000K
Frame format	CAN 2.0B extended frame (29-bit identifier)	Conforms to J1939 standard
Data length	8 bytes (classic J1939)	Classic PGN payload length; see the corresponding section for CANFD
Frame priority	3 (default)	Range: 0-7, 0 is the highest priority
Default node address	8	Configurable range: 1-127; broadcast address: 255
PF (PDU Format)	0xFF (proprietary PGN)	Vendor-defined PGN range
PS (PDU Specific)	Data type identifier	Distinguishes different sensor data types
Data format	Little-endian (LSB first)	Low byte of multi-byte data comes first
Data type	Signed / unsigned integers	Depends on specific PGN definition

PGN Message List

This product supports multiple J1939 PGN messages for sensor data. All PGNs use the vendor-defined format (PF=0xFF). Most classic J1939 PGNs contain 8-byte payloads encoded in little-endian; see the dedicated section for CANFD frames.

PGN 65327 (0xFF2F) - Time Information

Function: outputs UTC time information for status viewing or host parsing.

CAN identifier format: 0x0CFF2F[SA]

Priority: 3 (0x0C)
PF: 0xFF, PS: 0x2F
SA: source address (default 0x08)

Data format:

Byte	Field	Type	Range	Unit	Scale	Description
0	UTC year	uint8	0-99	year	1	20 represents 2020
1	UTC month	uint8	0-12	month	1	1-12
2	UTC day	uint8	0-31	day	1	1-31
3	UTC hour	uint8	0-23	hour	1	24-hour format
4	UTC minute	uint8	0-59	min	1	Minutes
5	UTC second	uint8	0-59	s	1	Seconds
6-7	UTC ms	uint16	0-999	ms	1	Milliseconds, little-endian

Output example:

CAN ID: 0x0CFF2F08
Data:   18 06 12 0E 1E 2D 58 02
Parsed: 2024-06-18 14:30:45.600 UTC

PGN 65332 (0xFF34) - Three-Axis Acceleration

Function: outputs three-axis acceleration measurements.

CAN identifier format: 0x0CFF34[SA]

Data format:

Byte	Field	Type	Range	Unit	Scale	Description
0-1	Acceleration X	int16	±32767	G	0.00048828	X-axis acceleration, little-endian
2-3	Acceleration Y	int16	±32767	G	0.00048828	Y-axis acceleration, little-endian
4-5	Acceleration Z	int16	±32767	G	0.00048828	Z-axis acceleration, little-endian
6-7	Reserved	uint16	0	-	-	Reserved, fixed at 0

PGN 65335 (0xFF37) - Three-Axis Angular Velocity

Function: outputs three-axis angular velocity (gyroscope) measurements.

CAN identifier format: 0x0CFF37[SA]

Data format:

Byte	Field	Type	Range	Unit	Scale	Description
0-1	Angular velocity X	int16	±32767	deg/s	0.061035	X-axis angular velocity, little-endian
2-3	Angular velocity Y	int16	±32767	deg/s	0.061035	Y-axis angular velocity, little-endian
4-5	Angular velocity Z	int16	±32767	deg/s	0.061035	Z-axis angular velocity, little-endian
6-7	Reserved	uint16	0	-	-	Reserved, fixed at 0

PGN 65341 (0xFF3D) - Pitch and Roll

Function: outputs pitch and roll attitude information.

CAN identifier format: 0x0CFF3D[SA]

Data format:

Byte	Field	Type	Range	Unit	Scale	Description
0-3	Roll	int32	±180,000,000	deg	0.001	Roll, little-endian
4-7	Pitch	int32	±90,000,000	deg	0.001	Pitch, little-endian

PGN 65345 (0xFF41) - Heading

Function: outputs heading (yaw) information in two representations.

CAN identifier format: 0x0CFF41[SA]

Data format:

Byte	Field	Type	Range	Unit	Scale	Description
0-3	Heading (0-360°)	uint32	0-360,000,000	deg	0.001	0-360°, clockwise positive, little-endian
4-7	Heading (±180°)	int32	±180,000,000	deg	0.001	±180°, counterclockwise positive, little-endian

PGN 65338 (0xFF3A) - Three-Axis Magnetic Field

Function: outputs three-axis magnetic field measurements.

CAN identifier format: 0x0CFF3A[SA]

Data format:

Byte	Field	Type	Range	Unit	Scale	Description
0-1	Magnetic field X	int16	±32767	μT	0.030517	X-axis magnetic field, little-endian
2-3	Magnetic field Y	int16	±32767	μT	0.030517	Y-axis magnetic field, little-endian
4-5	Magnetic field Z	int16	±32767	μT	0.030517	Z-axis magnetic field, little-endian
6-7	Reserved	uint16	0	-	-	Reserved, fixed at 0

PGN 65350 (0xFF46) - Quaternion

Function: outputs attitude quaternion.

CAN identifier format: 0x0CFF46[SA]

Data format:

Byte	Field	Type	Range	Unit	Scale	Description
0-1	Quaternion qw	int16	±32767	-	0.0001	Quaternion real part, little-endian
2-3	Quaternion qx	int16	±32767	-	0.0001	Quaternion i component, little-endian
4-5	Quaternion qy	int16	±32767	-	0.0001	Quaternion j component, little-endian
6-7	Quaternion qz	int16	±32767	-	0.0001	Quaternion k component, little-endian

PGN 65354 (0xFF4A) - Inclinometer Output

Function: dedicated angle output for inclinometer products.

Applicable scope: only for inclinometer products and firmware configurations with J1939 output enabled.

CAN identifier format: 0x0CFF4A[SA]

Data format:

Byte	Field	Type	Range	Unit	Scale	Description
0-3	X-axis tilt	int32	0-360,000,000	deg	0.001	X-axis tilt, configurable 0-360° or ±180°
4-7	Y-axis tilt	int32	0-360,000,000	deg	0.001	Y-axis tilt, configurable 0-360° or ±90°

PGN 65370 (0xFF5A) - CANFD Data Frame 0 - IMU Data

Function: when the product supports and enables CANFD output, it can output CANFD data frame 0, containing packed IMU data with a frame length of 64 bytes.

Applicable scope: only for products and firmware configurations that support and enable CANFD output.

CAN identifier format: 0x0CFF5A[SA]

Data format:

The payload is 64 bytes and contains the main status, timestamp, raw IMU data, attitude angles, quaternion, temperature, and other information.

Offset	Name	Type	Size (bytes)	Unit	Scale	Description
0	main_status	uint16	2	-	-	Status word, see `MAIN_STATUS` description
2	reserved	uint8	1	-	-	Reserved
3	reserved	uint8	1	-	-	Reserved
4	system_time	uint32	4	ms	1	Local timestamp (ms since power-up)
8	acc_x	int16	2	g	0.00048828	Acceleration X
10	acc_y	int16	2	g	0.00048828	Acceleration Y
12	acc_z	int16	2	g	0.00048828	Acceleration Z
14	gyr_x	int16	2	deg/s	0.061035	Angular velocity X
16	gyr_y	int16	2	deg/s	0.061035	Angular velocity Y
18	gyr_z	int16	2	deg/s	0.061035	Angular velocity Z
20	mag_x	int16	2	uT	0.030517	Magnetic field X
22	mag_y	int16	2	uT	0.030517	Magnetic field Y
24	mag_z	int16	2	uT	0.030517	Magnetic field Z
26	roll	int32	4	deg	0.001	Roll
30	pitch	int32	4	deg	0.001	Pitch
34	yaw	int32	4	deg	0.001	Yaw
38	qw	int16	2	-	0.0001	Quaternion w
40	qx	int16	2	-	0.0001	Quaternion x
42	qy	int16	2	-	0.0001	Quaternion y
44	qz	int16	2	-	0.0001	Quaternion z
46	temp	int16	2	℃	0.01	Module average temperature
48	reserved	uint8	16	-	-	Reserved

Configuration Protocol

Protocol Format

This product uses a J1939-based configuration protocol that allows the host to read and write some device parameters. Configuration messages use a dedicated PGN and are transmitted via the standard J1939 extended frame format.

Configuration frame format:

CAN identifier: 0x0CEF[DA][SA]
SA: source address; the address of the host initiating the configuration request; can be assigned on the host side.
DA: destination address; usually the product node ID; the broadcast address 255 may also be used.

Data payload format:

Byte	Field	Type	Description
0-1	ADDR	uint16	Register address, little-endian
2	CMD	uint8	Command type (0x06 = write, 0x03 = read)
3	STATUS	uint8	Status field (0 for write commands, status for read responses)
4-7	VAL	uint32	Data value, little-endian

Register Address Map

See the register list in the Modbus protocol chapter.

Configuration Examples

The following examples assume the factory default node ID 8.

29-bit extended ID	Data	Description	Notes
0x0CEF08xx	2F 01 06 00 [VAL]	VAL: 4 bytes	PGN:FF2F (UTC time) period, unit: ms, range: 5-1000
0x0CEF08xx	34 01 06 00 [VAL]	VAL: 4 bytes	PGN:FF34 (acceleration) period, unit: ms, range: 5-1000
0x0CEF08xx	37 01 06 00 [VAL]	VAL: 4 bytes	PGN:FF37 (angular velocity) period, unit: ms, range: 5-1000
0x0CEF08xx	3D 01 06 00 [VAL]	VAL: 4 bytes	PGN:FF3D (pitch/roll) period, unit: ms, range: 5-1000
0x0CEF08xx	41 01 06 00 [VAL]	VAL: 4 bytes	PGN:FF41 (heading) period, unit: ms, range: 5-1000
0x0CEF08xx	3A 01 06 00 [VAL]	VAL: 4 bytes	PGN:FF3A (magnetic field) period, unit: ms, range: 5-1000
0x0CEF08xx	46 01 06 00 [VAL]	VAL: 4 bytes	PGN:FF46 (quaternion) period, unit: ms, range: 5-1000
0x0CEF08xx	4A 01 06 00 [VAL]	VAL: 4 bytes	PGN:FF4A (inclinometer) period, unit: ms, range: 5-1000
0x0CEF08xx	5A 01 06 00 [VAL]	VAL: 4 bytes	PGN:FF5A (CANFD frame 0) period, unit: ms, range: 5-1000; valid only when CANFD output is supported and enabled
0x0CEF08xx	96 00 06 00 [PGN]	PGN: 4 bytes	Sync-trigger output. For example, with `PGN=0xFF34` (acceleration), sending `96 00 06 00 34 FF 00 00` triggers one acceleration frame. There is no response frame; the module sends the corresponding data frame on success
0x0CEF08xx	A5 00 06 00 [VAL]	VAL: 4 bytes	`VAL=1` Heading reset: zero the current heading `VAL=2` Set relative zero: zero current Pitch/Roll `VAL=3` Auto-level: auto-calibrate to horizontal `VAL=5` Cancel auto-level: clear relative Pitch/Roll
0x0CEF08xx	9D 00 06 00 01 00 00 00	-	Globally enable node data output (default)
0x0CEF08xx	9D 00 06 00 00 00 00 00	-	Globally disable node data output
0x0CEF08xx	00 00 06 00 00 00 00 00	-	Save all configuration to Flash
0x0CEF08xx	00 00 06 00 01 00 00 00	-	Restore default user configuration; auto-save and reset
0x0CEF08xx	00 00 06 00 FF 00 00 00	-	Reset
0x0CEF08xx	9A 00 06 00 [VAL]	VAL: 4 bytes	Configure baud rate (save, reset to take effect): 0:1000K, 1:800K, 2:500K, 3:250K, 4:125K
0x0CEF08xx	9C 00 06 00 [VAL]	VAL: 4 bytes	Set J1939 node ID: 1-127
0x0CEF08xx	9E 00 06 00 [VAL]	VAL: 4 bytes	Set inclinometer X axis polarity, 0: default, 1: reversed
0x0CEF08xx	9F 00 06 00 [VAL]	VAL: 4 bytes	Set inclinometer Y axis polarity, 0: default, 1: reversed

📋 Address note
The xx in the address field: source address (SA) in the J1939 identifier; can be any byte.
The xx in the data field: any byte.
Example: ID=0x0CEF0855, DATA = 37 01 06 00 64 00 00 00 sets PGN:FF37 (angular velocity) to a 100 ms period (10 Hz).

Time Synchronization

In the current firmware, J1939 PGN 65327 (time information) is used to output UTC time information; it is not used as an input channel for synchronizing the module's internal clock.

If UTC synchronization of the module time is required, use the PPS + UART time-message approach described in the earlier "Synchronous Input - SYNC_IN / PPS" chapter.

Notes

PGN 65327 can be used to read the UTC time currently output by the module;
The current firmware does not support clock synchronization via J1939 time frames;
For high-precision time synchronization, see the earlier PPS input and UART time-sync configuration requirements.

Output Example

The following example shows the module outputting one frame of time information over J1939, which the host can parse for the current UTC time:

CAN ID: 0x0CFF2F08
Data:   18 06 12 0E 1E 2D 58 02
Parsed:
- UTC year:   0x18 = 24 (2024)
- UTC month:  0x06 = 6  (June)
- UTC day:    0x12 = 18 (18th)
- UTC hour:   0x0E = 14
- UTC minute: 0x1E = 30
- UTC second: 0x2D = 45
- UTC ms:     0x0258 = 600

CAN Data Protocol (CANopen)

Products with a CAN interface usually use the J1939 stack by default. Some products or delivered configurations support CANopen slave communication; availability depends on the actual product model and delivered configuration. CANopen communication uses standard data frames; common data is transmitted via TPDO1/2/3/4/6/7 — remote frames and extended data frames are not used. By default, TPDO uses asynchronous periodic triggering; for synchronous mode, see the "Sync Protocol" section below.

CANopen Defaults

The following defaults apply to the standard delivered configuration; the actual values depend on the specific product model and delivered configuration.

Default	Value
CAN baud rate	500 kbit/s
Node ID	8
Initialization state	Operational
TPDO output rate	1 Hz - 200 Hz (per TPDO)

CANopen TPDO

Channel	Frame ID	DLC	Transmission mode	Frequency (Hz)	Data	Description
TPDO1	0x180+ID	6	Async timed (0xFE)	100	Acceleration	int16, low byte first, 2 bytes per axis, 6 bytes total; X, Y, Z acceleration in mG (0.001 G)
TPDO2	0x280+ID	6	Async timed (0xFE)	100	Angular velocity	int16, low byte first, 2 bytes per axis, 6 bytes total; X, Y, Z angular velocity in 0.1 deg/s
TPDO3	0x380+ID	6	Async timed (0xFE)	100	Euler angles	int16, low byte first, 2 bytes per axis, 6 bytes total; Roll, Pitch, Yaw in 0.01°
TPDO4	0x480+ID	8	Async timed (0xFE)	100	Quaternion	int16, low byte first, 2 bytes per element, 8 bytes total; w, x, y, z multiplied by 10000. For example, when the quaternion is 1,0,0,0 the output is 10000,0,0,0
TPDO6	0x680+ID	4	Async timed (0xFE)	20	Pressure	int32, 4 bytes, unit: Pa
TPDO7	0x780+ID	8	Async timed (0xFE)	100	Inclinometer angles	int32, low byte first, 4 bytes per axis, 8 bytes total; X axis, Y axis in 0.01°

Data Parsing Example

Acceleration and angular velocity parsing:

Acceleration CAN frame: ID=0x188, DATA = 4A 00 1F 00 C8 03

ID=0x188: acceleration frame sent by the device with node ID 8
Acceleration X = 0x004A = 74 = 74 mG
Acceleration Y = 0x001F = 31 = 31 mG
Acceleration Z = 0x03C8 = 968 = 968 mG

Angular velocity CAN frame: ID=0x288, DATA = 15 00 14 01 34 00

ID=0x288: angular velocity frame sent by the device with node ID 8
Angular velocity X = 0x0015 = 21 = 2.1 deg/s
Angular velocity Y = 0x0114 = 276 = 27.6 deg/s
Angular velocity Z = 0x0034 = 52 = 5.2 deg/s

Connecting to the CAN Device

Using PCAN-View with a PCAN adapter, the received CAN messages and their frame rates can be viewed in the Receive (Rx Message) window as shown below:

Configuration Commands (SDO Protocol)

The configuration commands in this section all use expedited SDO. For power-cycle retention, save the configuration to Flash after configuring.

SDO (Service Data Object) Protocol

Expedited SDO format:

Master sends SDO command to slave:

CAN_ID	CS (1B)	Object index (2B)	Sub-index (1B)	Data (4B)
0x600+ID	0x23 (write 4 B)	LSB first	Sub-index	Data, LSB first

Slave responds to master:

CAN_ID	CS (1B)	Object index (2B)	Sub-index (1B)	Data (4B)
0x580+ID	0x60 (write OK ACK)	LSB first	Sub-index	Reserved

Common Configuration Commands

Change Node ID (0x209C)

Command: ID=0x608, DATA=23,9C,20,00,[ID],00,00,00

ID range: 1-127
To retain across power cycles, save the configuration to Flash and reset (or power-cycle).

Save Configuration to Flash (0x2000)

Command: ID=0x608, DATA=23,00,20,00,00,00,00,00

Reset (0x2000)

Command: ID=0x608, DATA=23,00,20,00,FF,00,00,00

Restore Factory Defaults (0x2000)

Command: ID=0x608, DATA=23,00,20,00,01,00,00,00

⚠️ Warning Restoring factory defaults reverts the module to its default user configuration. After execution, the module automatically saves and resets. Some calibration-related parameters may be retained; use with caution.

Change CAN Baud Rate (0x209A)

Command: ID=0x608, DATA=23,9A,20,00,[BAUD_CODE]

To retain across power cycles, save the configuration to Flash and reset (or power-cycle).

Change CAN baud rate to 1000 kbit/s: ID=0x608, DATA=23,9A,20,00,00,00,00,00
Change CAN baud rate to 500 kbit/s: ID=0x608, DATA=23,9A,20,00,02,00,00,00
Change CAN baud rate to 250 kbit/s: ID=0x608, DATA=23,9A,20,00,03,00,00,00
Change CAN baud rate to 125 kbit/s: ID=0x608, DATA=23,9A,20,00,04,00,00,00

TPDO Configuration

The following operations write the corresponding object dictionary entries via expedited SDO. The mapping between TPDO channels and parameter indexes is:

Channel	Frame ID	Parameter index	Description
TPDO1	0x180+ID	0x1800	Acceleration
TPDO2	0x280+ID	0x1801	Angular velocity
TPDO3	0x380+ID	0x1802	Euler angles
TPDO4	0x480+ID	0x1803	Quaternion
TPDO6	0x680+ID	0x1804	Pressure
TPDO7	0x780+ID	0x1805	Inclinometer

Set / Disable / Enable Output Rate (0x1800-0x1805)

📋 Note These settings take effect immediately after writing; save the configuration separately if power-cycle retention is needed.

Common configuration examples:

ID=0x608, DATA=2B,00,18,05,00,00,00,00 — disable acceleration output (1800.5=0)
ID=0x608, DATA=2B,00,18,05,05,00,00,00 — acceleration 200 Hz output (1800.5=5)
ID=0x608, DATA=2B,00,18,05,0A,00,00,00 — acceleration 100 Hz output (1800.5=10)
ID=0x608, DATA=2B,00,18,05,14,00,00,00 — acceleration 50 Hz output (1800.5=20)
ID=0x608, DATA=2B,00,18,05,32,00,00,00 — acceleration 20 Hz output (1800.5=50)
ID=0x608, DATA=2B,00,18,05,64,00,00,00 — acceleration 10 Hz output (1800.5=100)

Angular velocity configuration:

ID=0x608, DATA=2B,01,18,05,00,00,00,00 — disable angular velocity output (1801.5=0)
ID=0x608, DATA=2B,01,18,05,05,00,00,00 — angular velocity 200 Hz output (1801.5=5)
ID=0x608, DATA=2B,01,18,05,0A,00,00,00 — angular velocity 100 Hz output (1801.5=10)
ID=0x608, DATA=2B,01,18,05,14,00,00,00 — angular velocity 50 Hz output (1801.5=20)
ID=0x608, DATA=2B,01,18,05,32,00,00,00 — angular velocity 20 Hz output (1801.5=50)
ID=0x608, DATA=2B,01,18,05,64,00,00,00 — angular velocity 10 Hz output (1801.5=100)

Euler angle configuration:

ID=0x608, DATA=2B,02,18,05,00,00,00,00 — disable Euler angle output (1802.5=0)
ID=0x608, DATA=2B,02,18,05,05,00,00,00 — Euler angles 200 Hz output (1802.5=5)
ID=0x608, DATA=2B,02,18,05,0A,00,00,00 — Euler angles 100 Hz output (1802.5=10)
ID=0x608, DATA=2B,02,18,05,14,00,00,00 — Euler angles 50 Hz output (1802.5=20)
ID=0x608, DATA=2B,02,18,05,32,00,00,00 — Euler angles 20 Hz output (1802.5=50)
ID=0x608, DATA=2B,02,18,05,64,00,00,00 — Euler angles 10 Hz output (1802.5=100)

Quaternion configuration:

ID=0x608, DATA=2B,03,18,05,00,00,00,00 — disable quaternion output (1803.5=0)
ID=0x608, DATA=2B,03,18,05,05,00,00,00 — quaternion 200 Hz output (1803.5=5)
ID=0x608, DATA=2B,03,18,05,0A,00,00,00 — quaternion 100 Hz output (1803.5=10)
ID=0x608, DATA=2B,03,18,05,14,00,00,00 — quaternion 50 Hz output (1803.5=20)
ID=0x608, DATA=2B,03,18,05,32,00,00,00 — quaternion 20 Hz output (1803.5=50)
ID=0x608, DATA=2B,03,18,05,64,00,00,00 — quaternion 10 Hz output (1803.5=100)

Pressure configuration:

ID=0x608, DATA=2B,04,18,05,00,00,00,00 — disable pressure output (1804.5=0)
ID=0x608, DATA=2B,04,18,05,05,00,00,00 — pressure 200 Hz output (1804.5=5)
ID=0x608, DATA=2B,04,18,05,0A,00,00,00 — pressure 100 Hz output (1804.5=10)
ID=0x608, DATA=2B,04,18,05,14,00,00,00 — pressure 50 Hz output (1804.5=20)
ID=0x608, DATA=2B,04,18,05,32,00,00,00 — pressure 20 Hz output (1804.5=50)
ID=0x608, DATA=2B,04,18,05,64,00,00,00 — pressure 10 Hz output (1804.5=100)

📋 Configuration example Taking TPDO1 (acceleration) at 100 Hz (one frame every 10 ms) as an example: 0x23 indicates an SDO write of 4 bytes; 0x00 0x18 is the index 0x1800; 0x05 is the sub-index; 0x0A 0x00 is the period value 10 (unit: ms); the remaining bytes are zero-padded.

Set Inclinometer Zero (0x20A5)

ID=0x608, DATA=23,A5,20,00,02,00,00,00 — set the current position as the output zero point (X=0, Y=0)
ID=0x608, DATA=23,A5,20,00,05,00,00,00 — cancel zero configuration and output real X/Y angles (equivalent to X/Y offset = 0)

Sync Protocol

The module supports configuring each TPDO into synchronous mode. When enabled, the module stops asynchronous periodic transmission and waits for the CANopen sync frame; when the sync frame arrives, it sends one corresponding TPDO frame.

Configure a TPDO into Sync Mode

To configure a TPDO into sync mode, set the corresponding TPDO communication parameter [0x180x.2] (Transmission type) to 0x01. See the standard CANopen specification for field definitions.

Taking TPDO1 (acceleration) as an example:

ID=0x608, DATA=2F,00,18,02,01,00,00,00 — write [0x1800.2] = 1, set TPDO1 to sync mode
ID=0x608, DATA=2F,00,18,02,FF,00,00,00 — write [0x1800.2] = 0xFF, set TPDO1 to async mode (factory default)

Send CANopen Sync Frame

Send a CANopen sync frame: ID=0x80, no data

When the module receives the sync frame, all TPDOs configured in sync mode send one frame of data to achieve synchronization.

Set Heartbeat

The heartbeat period is set by writing [0x1017.0], valid range 0~65535, unit: ms. 0 disables the heartbeat.

Example: ID=0x608, DATA=2B,17,10,00,64,00,00,00 — set the heartbeat period to 100 ms

Magnetic Calibration

When to Use Magnetic Calibration

9-axis mode (magnetometer-aided absolute-heading mode) is recommended when the following conditions are met:

Perform at least one user magnetic calibration before using 9-axis mode for the first time.
There is no obvious spatial magnetic interference in the operating environment; calibration is recommended in open outdoor areas. Indoor environments with complex magnetic conditions are unlikely to produce good calibration results.
The relative position between the module and the mounting platform (PCB, housing, robot, etc.) remains fixed during use.

Calibration Procedure

When using the module for the first time and AHRS (9-axis) mode is required, follow the steps below:

1. Switch Mode

First, switch the module to 9-axis mode. See "Operating Mode Configuration".

2. Environment Check

Common magnetic interference sources: iron furniture, computer monitors, motors and transformers, mobile phone chargers, rebar in building structures.

Recommended calibration environments:

Best: outdoor open area, away from buildings and vehicles (distance > 5 m)
Acceptable: indoor area away from interference sources (distance > 30 cm)

⚠️ Important
If the module has been installed on a product PCB, or the product has a magnetic housing, or it has been installed on a robot/machine, the assembly must be treated as a whole during calibration. Calibrating the module alone and then installing it does not achieve the required effect.

3. Calibration Operation

Send the calibration command: CONFIG MCAL START (firmware version ≥ 1.7.0 required)

Perform the calibration motion:

Within a small physical region, keep the position essentially fixed and only slowly rotate the module.
Rotate each axis at least 360° (recommended 2~3 turns), at a uniform speed, around 20~100 deg/s (about 5~20 s per turn). Avoid pauses.
Calibration usually takes 30~60 s.

Recommended rotation plan: rotate 2 turns about X, then 2 turns about Y, then 2 turns about Z, or rotate randomly while making sure each axis sees sufficient angular change.

4. Query Calibration Status

Send: LOG MCAL STAT

Example response:

STAT=1
PROGRESS=8
OK

STAT field

STAT value	State description	Suggested action
0	Idle	A new calibration can be started
1	Calibrating	Keep rotating until calibration completes
2	Verifying result	Keep stationary, wait for verification
3	Calibration complete	Success; ready for normal use
4	Calibration failed	See the troubleshooting flow; recalibrate

PROGRESS: range 0~100, indicates the current calibration progress percentage. When PROGRESS=100 and STAT=3, calibration is successful.

5. Verify Calibration Result

After calibration, place the module horizontally and slowly rotate one full turn (360°).
Observe the heading output: it should change continuously from 0° to 360° without jumps; acceptable error is within ±5°.
If you see large jumps (>10°) or the heading does not change with rotation, see the troubleshooting flow below.

Calibration Troubleshooting Flow

If calibration fails (STAT=4) or the verification result is abnormal, troubleshoot as follows:

Step 1: Check ambient magnetic field strength

Place the module stationary at the calibration position, read the magnetic field strength (mag_b), and compute the total magnetic field magnitude: B_total = √(Bx² + By² + Bz²).

Magnetic field strength	Environmental assessment	Recommended action
20-60 μT	Normal	Continue calibration
< 20 μT or > 60 μT	Abnormal	Check for nearby strong magnetic objects; move away from interference sources; change location if necessary

Step 2: Check the rotation motion — make sure each axis is rotated at least 360° at a uniform speed of 20~100 deg/s, with no pauses.

Step 3: Check for spatial magnetic interference — measure the magnetic field strength at the same location with different orientations. If the variation is > 10 μT, there is spatial magnetic interference; change location or switch to 6-axis mode.

Common Issues and Solutions

Failure cause	Typical symptom	Solution
Strong ambient magnetic interference	STAT=4 or heading jumps	Move to an outdoor open area
Non-standard rotation	PROGRESS grows slowly or stagnates	Ensure each axis rotates sufficiently, at uniform speed
Position drift during rotation	Calibration completes but accuracy is poor	Keep the position fixed during calibration, only rotate orientation
Module-platform relative position changes	Heading error increases after reinstallation	Treat the module and platform as a unit and recalibrate

Important Reminders

⚠️ Warning 1: Indoor magnetic environment limitations — indoor spatial magnetic interference is severe and cannot be removed by calibration. Heading accuracy of the mag-aided (9-axis) mode strongly depends on the level of indoor magnetic distortion.

⚠️ Warning 2: Indoor usage suggestion — if the indoor magnetic environment is poor (server rooms, labs, workshops, underground parking lots, etc.), even a successful calibration may yield heading accuracy worse than 6-axis mode and large angular errors (>10°). In indoor environments, 6-axis mode is recommended.

⚠️ Warning 3: Fixed-installation requirement — if the installation environment contains magnetic interference, the interference source must maintain a fixed relative position to the module. When the module is mounted on a ferromagnetic rigid body (robot / machine / vehicle / vessel / tripod / PCB, etc.), the whole system must be rotated together during calibration. The module must not be displaced relative to the mounting platform during use; if separated, recalibrate.

⚠️ Warning 4: Motor vibration effects — vibration and magnetic interference from running robot motors can affect calibration. Calibrate with motors stopped, or calibrate while the motor is running in its working state (treating the motor field as a fixed interference source).

Calibration Frequency and Mode Selection

Calibration frequency suggestions:

For fixed installation in a stable environment, one initial calibration is sufficient;
For mobile applications, recalibrate after each environment change;
Recalibrate whenever the relative position between module and platform changes;
For long-term use (>1 year), recalibrate once per year;
Recalibrate immediately if abnormal heading errors appear.

Mode selection suggestions:

Application scenario	Recommended mode	Reason
Outdoor open environment (UAV)	9-axis mode	Low magnetic interference; absolute heading available
Indoor environment (AGV, robot)	6-axis mode	High indoor interference; 6-axis is more stable
Near motors / electromagnetic devices	6-axis mode	Electromagnetic interference cannot be removed by calibration
Absolute heading required	9-axis mode	Requires stable magnetic environment and proper calibration
Only relative heading required	6-axis mode	6-axis heading starts at 0 on power-up; suitable for relative measurement

Appendix 1: Quaternion / Euler Angle / Rotation Matrix Conversion

Quaternion to Rotation Matrix

Given a quaternion $[Q_{b 2 n} = [q_{0}, q_{1}, q_{2}, q_{3}]^{T}]$ , the direction cosine matrix is:

C_{b 2 n} = [\begin{matrix} q_{0}^{2} + q_{1}^{2} - q_{2}^{2} - q_{3}^{2} & 2 (q_{1} q_{2} - q_{0} q_{3}) & 2 (q_{1} q_{3} + q_{0} q_{2}) \\ 2 (q_{1} q_{2} + q_{0} q_{3}) & q_{0}^{2} - q_{1}^{2} + q_{2}^{2} - q_{3}^{2} & 2 (q_{2} q_{3} - q_{0} q_{1}) \\ 2 (q_{1} q_{3} - q_{0} q_{2}) & 2 (q_{2} q_{3} + q_{0} q_{1}) & q_{0}^{2} - q_{1}^{2} - q_{2}^{2} + q_{3}^{2} \end{matrix}]

Quaternion to Euler Angles - East-North-Up (ENU)-312 rotation order (Z, then X, then Y)

Given a quaternion $Q_{b 2 n} = [q_{0}, q_{1}, q_{2}, q_{3}]^{T}$ , where $q_{0}$ is the scalar part and $[q_{1}, q_{2}, q_{3}]$ is the vector part. $Q_{b 2 n}$ represents the rotation from the body frame (b) to the navigation frame (n), where:

pitch (θ): rotation about the X axis, range $[- \frac{π}{2}, \frac{π}{2}]$
roll (φ): rotation about the Y axis, range $[- π, π]$
yaw (ψ): rotation about the Z axis, range $[- π, π]$

Quaternion to Euler:

p i t c h = \arcsin (2 (q_{0} q_{1} + q_{2} q_{3})) r o l l = - \arctan 2 (2 (q_{1} q_{3} - q_{0} q_{2}), q_{0}^{2} - q_{1}^{2} - q_{2}^{2} + q_{3}^{2}) y a w = - \arctan 2 (2 (q_{1} q_{2} - q_{0} q_{3}), q_{0}^{2} - q_{1}^{2} + q_{2}^{2} - q_{3}^{2})

Euler to quaternion:

[\begin{matrix} q_{0} \\ q_{1} \\ q_{2} \\ q_{3} \end{matrix}] = [\begin{matrix} \cos (\frac{pitch}{2}) \cos (\frac{roll}{2}) \cos (\frac{yaw}{2}) - \sin (\frac{pitch}{2}) \sin (\frac{roll}{2}) \sin (\frac{yaw}{2}) \\ \cos (\frac{roll}{2}) \cos (\frac{yaw}{2}) \sin (\frac{pitch}{2}) - \cos (\frac{pitch}{2}) \sin (\frac{roll}{2}) \sin (\frac{yaw}{2}) \\ \cos (\frac{pitch}{2}) \cos (\frac{yaw}{2}) \sin (\frac{roll}{2}) + \cos (\frac{roll}{2}) \sin (\frac{pitch}{2}) \sin (\frac{yaw}{2}) \\ \cos (\frac{pitch}{2}) \cos (\frac{roll}{2}) \sin (\frac{yaw}{2}) + \sin (\frac{pitch}{2}) \sin (\frac{roll}{2}) \cos (\frac{yaw}{2}) \end{matrix}]

Quaternion to Euler Angles - North-East-Down (NED)-321 rotation order (Z, then Y, then X)

pitch (θ): rotation about the Y axis, range $[- \frac{π}{2}, \frac{π}{2}]$
roll (φ): rotation about the X axis, range $[- π, π]$
yaw (ψ): rotation about the Z axis, range $[- π, π]$

Quaternion to Euler:

r o l l = \arctan 2 (2 (q_{0} q_{1} + q_{2} q_{3}), 1 - 2 (q_{1}^{2} + q_{2}^{2})) p i t c h = \arcsin (2 (q_{0} q_{2} - q_{1} q_{3})) y a w = \arctan 2 (2 (q_{0} q_{3} + q_{1} q_{2}), 1 - 2 (q_{2}^{2} + q_{3}^{2}))

Euler to quaternion:

[\begin{matrix} q_{0} \\ q_{1} \\ q_{2} \\ q_{3} \end{matrix}] = [\begin{matrix} \cos (\frac{roll}{2}) \cos (\frac{pitch}{2}) \cos (\frac{yaw}{2}) + \sin (\frac{roll}{2}) \sin (\frac{pitch}{2}) \sin (\frac{yaw}{2}) \\ \sin (\frac{roll}{2}) \cos (\frac{pitch}{2}) \cos (\frac{yaw}{2}) - \cos (\frac{roll}{2}) \sin (\frac{pitch}{2}) \sin (\frac{yaw}{2}) \\ \cos (\frac{roll}{2}) \sin (\frac{pitch}{2}) \cos (\frac{yaw}{2}) + \sin (\frac{roll}{2}) \cos (\frac{pitch}{2}) \sin (\frac{yaw}{2}) \\ \cos (\frac{roll}{2}) \cos (\frac{pitch}{2}) \sin (\frac{yaw}{2}) - \sin (\frac{roll}{2}) \sin (\frac{pitch}{2}) \cos (\frac{yaw}{2}) \end{matrix}]

Appendix 2: Firmware Upgrade

This product supports firmware upgrade. Use the CHCenter host software and follow the steps shown below; contact technical support to obtain the firmware upgrade file (.hex).

Appendix 3: More on Magnetic Interference

Magnetic interference can be divided into spatial magnetic interference and sensor-frame magnetic interference, as shown below:

Type of magnetic interference	Sensor-frame magnetic interference (hard-iron / soft-iron)	Spatial magnetic interference
Characteristics	The interference source moves with the sensor	The interference source does not move with the sensor
Typical sources	PCB, metal housing, UAV, etc., fixed to the module	Furniture, household appliances, cables, rebar in buildings
Calibration feasibility	Yes	No
Mitigation	Can be removed by the user magnetic calibration procedure	Cannot be removed by any calibration; severely degrades heading accuracy

Notes on spatial magnetic interference Spatial magnetic interference is the main reason why indoor magnetometer fusion is hard to use reliably. This type of interference cannot be removed by calibration and significantly increases heading error. In indoor environments, especially near desks, chairs, and appliances, this interference is usually more pronounced.

📋 Legend The figure above shows a typical distribution of indoor spatial magnetic interference: blue represents weak-interference regions, red represents strong-interference regions.

Appendix 5: Technical Support

The latest product and documentation information is available on our official website and WeChat account. WeChat:

Telegram:

Command and Programming Manual ​

Manual Version Notes (Important) ​

Module Configuration Overview ​

Operating Mode Configuration - AHRS / 9-Axis Mode ​

Synchronous Input - SYNC_IN / PPS ​

SYNC_IN Data Trigger ​

PPS Standard Pulse Input ​

1. Timing and Signal Requirements ​

2. Hardware and Interface Requirements ​

3. Time Message Example (GPRMC) ​

Synchronous Output - SOUT ​

Vessel Wave-Compensated Displacement Output - Heave, Surge, Sway ​

Usage Limitations ​

Product Feature Support Matrix ​

Module Configuration Commands (ASCII) ​

Command Overview ​

Command Details ​

REBOOT ​

SAVECONFIG ​

SERIALCONFIG ​

CONFIG ​

Operating Mode Configuration ​

User Attitude Calibration ​

Mounting Orientation Setting ​

Multi-Function IO Multiplexing Configuration ​

SOUT (PMUX2) Sync-Output Divider ​

Magnetic Calibration ​

Coordinate System Definition ​

User-Level Gyroscope Calibration ​

LOG ​

Enable/Disable Data Output ​

Module Version Information ​

Display UART Configuration ​

Set Output Frame Type and Rate ​

HI83 Variable-Length Frame Configuration ​

FRESET ​

RS-232/TTL/USB Data Protocol (Binary) ​

Data Frame Format ​

Factory Default Output ​

Payload Content ​

Floating-Point IMU Data Frame (HI91) ​

Variable-Length Protocol (HI83) ​

data_bitmap Bits and Data Segments ​

MAIN_STATUS Status Word Description ​

CRC Verification ​

Data Frame Example (HI91) ​

C Parsing Code Example (HI91) ​

CRC Check ​

Define Receive Data Structure ​

Receive Data ​

Print Received Data ​

Maximum Transmission Rate ​

RS-485 Output Protocol (Modbus) ​

Modbus Command Description ​

Data Frame Format ​

Read Registers (0x03) ​

Write Register (0x06) ​

Register List ​

Common Configurations ​

Save Configuration to Flash ​

Restore Factory Defaults ​

Reset ​

Configure Baud Rate (0x04) ​

Configure Node ID (0x05) ​

Set Mounting Orientation (0xA6) ​

Set Auto-Level (0xA5) ​

Set 6-Axis or 9-Axis Mode (0x06) ​

Read Module Version Information (0x70-0x82) ​

Read Sensor Data (0x34-0x4B) ​

CAN Data Protocol (J1939) ​

CAN Extended Frame Format ​

Byte Order (Endianness) ​

CANFD Support ​

Protocol Parameters ​

PGN Message List ​

PGN 65327 (0xFF2F) - Time Information ​

PGN 65332 (0xFF34) - Three-Axis Acceleration ​

PGN 65335 (0xFF37) - Three-Axis Angular Velocity ​

PGN 65341 (0xFF3D) - Pitch and Roll ​

PGN 65345 (0xFF41) - Heading ​

Command and Programming Manual

Manual Version Notes (Important)

Module Configuration Overview

Operating Mode Configuration - AHRS / 9-Axis Mode

Synchronous Input - SYNC_IN / PPS

SYNC_IN Data Trigger

PPS Standard Pulse Input

1. Timing and Signal Requirements

2. Hardware and Interface Requirements

3. Time Message Example (GPRMC)

Synchronous Output - SOUT

Vessel Wave-Compensated Displacement Output - Heave, Surge, Sway

Usage Limitations

Product Feature Support Matrix

Module Configuration Commands (ASCII)

Command Overview

Command Details

REBOOT

SAVECONFIG

SERIALCONFIG

CONFIG

Operating Mode Configuration

User Attitude Calibration

Mounting Orientation Setting

Multi-Function IO Multiplexing Configuration

SOUT (PMUX2) Sync-Output Divider

Magnetic Calibration

Coordinate System Definition

User-Level Gyroscope Calibration

LOG

Enable/Disable Data Output

Module Version Information

Display UART Configuration

Set Output Frame Type and Rate

HI83 Variable-Length Frame Configuration

FRESET

RS-232/TTL/USB Data Protocol (Binary)

Data Frame Format

Factory Default Output

Payload Content

Floating-Point IMU Data Frame (HI91)

Variable-Length Protocol (HI83)

data_bitmap Bits and Data Segments

MAIN_STATUS Status Word Description

CRC Verification

Data Frame Example (HI91)

C Parsing Code Example (HI91)

CRC Check

Define Receive Data Structure

Receive Data

Print Received Data

Maximum Transmission Rate

RS-485 Output Protocol (Modbus)

Modbus Command Description

Data Frame Format

Read Registers (0x03)

Write Register (0x06)

Register List

Common Configurations

Save Configuration to Flash

Restore Factory Defaults

Reset

Configure Baud Rate (0x04)

Configure Node ID (0x05)

Set Mounting Orientation (0xA6)

Set Auto-Level (0xA5)

Set 6-Axis or 9-Axis Mode (0x06)

Read Module Version Information (0x70-0x82)

Read Sensor Data (0x34-0x4B)

CAN Data Protocol (J1939)

CAN Extended Frame Format

Byte Order (Endianness)

CANFD Support

Protocol Parameters

PGN Message List

PGN 65327 (0xFF2F) - Time Information

PGN 65332 (0xFF34) - Three-Axis Acceleration

PGN 65335 (0xFF37) - Three-Axis Angular Velocity

PGN 65341 (0xFF3D) - Pitch and Roll

PGN 65345 (0xFF41) - Heading