9-Axis Sensor (imu)

This module manages the BMI270+BMM150 9-axis sensor module (3-axis accelerometer, 3-axis gyroscope, 3-axis magnetometer). It uses a shared I2C driver for initialization and data reading.

• Fixed I2C pins:
  • SCL = GPIO 1
  • SDA = GPIO 2
  • Speed = 100kHz

Methods

1. imu.init() -> int

Function: Initialize the IMU sensor module.

• Automatically initializes the shared I2C interface internally;
• Only initializes once; repeated calls directly return the previous result;
• Returns 0 on successful initialization, non-zero on failure (determined by the imu_init() return value).

Example:

import imu

ret = imu.init()
if ret == 0:
    print("IMU initialized successfully")
else:
    print("IMU initialization failed, error code:", ret)

2. imu.read_9axis() -> (int, (float, float, float), (float, float, float), (float, float, float))

Function: Read the 9-axis sensor data.

Return value:

Returns a 4-tuple in the following format:

(rslt, accel, gyro, mag)

• rslt: read status code, 0 means success, non-zero means failure.
• accel: 3-tuple (ax, ay, az), unit usually g.
• gyro: 3-tuple (gx, gy, gz), unit usually °/s.
• mag: 3-tuple (mx, my, mz), unit usually μT.

Example:

rslt, accel, gyro, mag = imu.read_9axis()

if rslt == 0:
    print("Accelerometer:", accel)
    print("Gyroscope:", gyro)
    print("Magnetometer:", mag)
else:
    print("Read failed, error code:", rslt)

Simple Usage Example

import imu
import time

# Initialize
ret = imu.init()
if ret != 0:
    print("IMU initialization failed")
else:
    while True:
        rslt, accel, gyro, mag = imu.read_9axis()
        if rslt == 0:
            print("Accelerometer:", accel)
            print("Gyroscope:", gyro)
            print("Magnetometer:", mag)
        else:
            print("Read failed")

        time.sleep(0.5)

⚠ Notes

• Always check whether the return value rslt is 0 on every read;
• I2C pins are fixed to GPIO 1 (SCL) and GPIO 2 (SDA);
• If there are other devices on the I2C bus, watch out for address conflicts;
• This module does not perform unit conversion; refer to the BMI270+BMM150 datasheet for unit interpretation.

Module Hardware Support

Sensor	Description
BMI270	3-axis accelerometer + 3-axis gyroscope
BMM150	3-axis magnetometer