Gravity: 9 DOF IMU Sensor

1. Example Code for Arduino-Reading Data via I2C

This tutorial demonstrates how to initialize a 9 DOF IMU sensor and directly read acceleration, angular velocity, and magnetometer data using the polling method.

2. Example Code for Arduino-Reading Data via UART and Interrupts

This tutorial demonstrates how to configure a 9 DOF IMU sensor to trigger a hardware interrupt when data is ready, and read acceleration, angular velocity, and magnetometer data in the interrupt service routine to achieve efficient data acquisition.

3. Usage Example for Host Computer Software

This guide provides a detailed walkthrough on connecting the 9 DOF IMU sensor to the RainbowLink V2 using host computer software. The process includes hardware and software setup, configuring communication modes, and collecting real-time data such as acceleration and gyroscope values.

4. Modbus Register Definitions

This guide details Modbus Register Definitions, covering both input and holding registers. Learn about function codes and how to read 3-axis acceleration data from a 9DOF IMU sensor.

Reference

Specification

Basic Parameters

Parameter	Value
Operating Voltage	DC 3.3–5 V
Operating Current	3.42 mA
Communication Interface	I2C / UART
Interface Type	PH2.0-4P (Gravity pin order) / 2.54 mm pin header
I2C Address	0x4A (default) / 0x4B / 0x4C / 0x4D
Programmable Interrupt Pins	BMI323: 2 channels BMM350: 1 channel

Accelerometer Parameters

Parameter	Value
Measurement Range	±2 g, ±4 g, ±8 g, ±16 g
ADC Resolution	16-bit
Sensitivity	±2 g range: 16384 LSB/g ±4 g range: 8192 LSB/g ±8 g range: 4096 LSB/g ±16 g range: 2048 LSB/g
Sensitivity Error	±0.5%
Zero-g Offset	±50 mg
Output Data Rate (ODR)	High Performance / Normal Mode: 12.5 Hz ~ 6400 Hz Low Power Mode: 0.78125 Hz ~ 400 Hz

Gyroscope Parameters

Parameter	Value
Angular Velocity Range	±125, ±250, ±500, ±1000, ±2000 °/s
ADC Resolution	16-bit
Sensitivity	±2000 °/s range: 16.384 LSB/(°/s) ±1000 °/s range: 32.768 LSB/(°/s) ±500 °/s range: 65.536 LSB/(°/s) ±250 °/s range: 131.072 LSB/(°/s)
Sensitivity Error	±3% (without auto‑calibration) / ±0.7% (after auto‑calibration)
Zero-rate Offset	±1 °/s
Output Data Rate (ODR)	High Performance / Normal Mode: 12.5 Hz ~ 6400 Hz Low Power Mode: 0.78125 Hz ~ 400 Hz

Magnetometer Parameters

Parameter	Value
Operating Modes	Normal mode (periodic measurement), Forced mode (triggered measurement), Sleep mode (low-power standby)
Measurement Range	±2000 µT
Magnetic Resolution	~0.1 µT
Zero-field Offset Drift (after soldering)Zero-field Offset (after calibration)	±2 µT (-40 °C ~ +85 °C, calibrated with Bosch eCompass software)
X/Y Axis Gain Error	±1% (25 °C, after API compensation)
Z Axis Gain Error	±3% (25 °C, after API compensation)
Temperature Coefficient of Sensitivity (TCS)	±0.010 %/K
Temperature Offset Error (TCOerr)	±200 nT/K
Normal Mode ODR	400 / 200 / 100 / 50 / 25 / 12.5 / 6.25 / 3.125 / 1.5625 Hz (typical tolerance ±2%)
Max Trigger Frequency in Forced Mode	200 Hz (only when avg=0)
X/Y Axis Output Noise (rms)	190 nTrms (ODR=100 Hz, 2 samples averaged, 3 dB bandwidth = ODR/2)
Z Axis Output Noise (rms)	450 nTrms (ODR=100 Hz, 2 samples averaged, 3 dB bandwidth = ODR/2)

Physical Dimensions

Parameter	Value
PCB Size	32 mm × 27 mm
Mounting Hole Spacing	20 mm
Mounting Hole Diameter	3 mm

Pinout

SEN0694-Pinout

Interface Pin Description

Pin Silkscreen	Function Description
+	Positive Power Supply (Input: 3.3–5 V)
-	Negative Power Supply (GND)
C/R	Multifunction Pin: SCL in I2C mode, RXD in UART mode
D/T	Multifunction Pin: SDA in I2C mode, TXD in UART mode
INT1	BMI323 Interrupt Output Pin 1
INT2	BMI323 Interrupt Output Pin 2
INT3	BMM350 Interrupt Output Pin

I2C Address Setting Switch Description

I2C Address	A0	A1
0x4A	0	0
0x4B	1	0
0x4C	0	1
0x4D	1	1

Notes

The setting of the I2C/UART Switch is saved when powered off. The new mode takes effect after restarting the device.