M5Stack AtomS3R BMI270 FIFO Arduino Sketch

This repo contains an Arduino .ino project for reading BMI270 IMU data through the sensor FIFO on an M5Stack AtomS3R-class target.

Project layout

• atomS3R_bmi270_fifo/atomS3R_bmi270_fifo.ino – sketch entrypoint that wires together reusable IMU and magnetometer readers.
• atomS3R_bmi270_fifo/ImuReader.h – header-only reusable BMI270 FIFO setup + sample extraction class.
• atomS3R_bmi270_fifo/MagReader.h – header-only reusable BMM150-over-AUX setup + sample decode class.
• .github/workflows/arduino-build.yml – GitHub Actions workflow that installs Arduino CLI, the ESP32 core, SparkFun BMI270 library, and compiles the sketch.

AtomS3R hardware notes

• The internal BMI270/BMM150 sensor chain on AtomS3R is reached on the internal sensor I2C bus (SDA=GPIO45, SCL=GPIO0).
• The sketch initializes Wire explicitly with Wire.begin(45, 0, 400000) and passes that bus to imu.beginI2C(...).
• BMI270 initialization probes both valid BMI270 I2C addresses (0x68 then 0x69) with short retry windows and fails fast if neither responds, so startup errors are explicit instead of silently retrying forever.
• Acceleration is converted to SI units (m/s^2) before logging.
• Accelerometer range is explicitly configured to ±2g during IMU setup.
• Gyroscope is logged in degrees/second (dps).
• Magnetometer values are synchronized into BMI270 FIFO AUX payload bytes and decoded from the latest drained frame, then printed in microtesla (uT) using a simple LSB-to-uT scaling for bring-up/debug timing.
• Loop pacing targets the IMU ODR (200 Hz) by sleeping only the remaining time in each 5 ms cycle, rather than a fixed delay(5).

Build target

The workflow compiles for FQBN:

• esp32:esp32:m5stack_atoms3

AtomS3R uses the same ESP32-S3 family as AtomS3, making this a practical CI target for AtomS3R sketches.

Local compile (optional)

arduino-cli core install esp32:esp32
arduino-cli lib install "SparkFun BMI270 Arduino Library"
arduino-cli compile --fqbn esp32:esp32:m5stack_atoms3 atomS3R_bmi270_fifo