📘 BMI270 7Semi Library

This repository contains basic, well-documented examples for using the Bosch BMI270 IMU with an ESP32, using the 7Semi_BMI270 library.

Supported interfaces: I2C / SPI

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🔌 Connection Guide

🟢 I2C Connection (Default & Recommended)

BMI270 Pin	ESP32 Pin	Notes
VCC	3.3V	check your board's tolerance
GND	GND	Common ground
SDA	GPIO 21	Can be changed
SCL	GPIO 22	Can be changed
SDO	LOW	Sets I2C address to 0x68

I2C Address:

• 0x68 → SDO = LOW
• 0x69 → SDO = HIGH

I2C Speed:

• Recommended: 400 kHz
• Supported: up to 1 MHz

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🔵 SPI Connection (Advanced)

⚠️ Important: BMI270 selects SPI or I2C at power-up. To force SPI mode, CS must be LOW during power-up.

ESP32 VSPI Wiring:

BMI270 Pin	ESP32 Pin	Notes
CS	GPIO 5	Must be LOW at boot
SCK	GPIO 18	VSPI clock
MISO	GPIO 19	VSPI MISO
MOSI	GPIO 23	VSPI MOSI
VCC	3.3V	Required
GND	GND	Required

SPI Configuration:

• Mode: SPI MODE 0
• Init speed: ≤ 1 MHz
• Normal speed: ≤ 10 MHz

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⚙️ Sensor Configuration

🧭 Accelerometer

Output Data Rate (ODR):

• BMI2_ACC_ODR_0_78HZ (ultra low power)
• BMI2_ACC_ODR_12_5HZ
• BMI2_ACC_ODR_25HZ
• BMI2_ACC_ODR_50HZ
• BMI2_ACC_ODR_100HZ ← recommended
• BMI2_ACC_ODR_200HZ
• BMI2_ACC_ODR_400HZ
• BMI2_ACC_ODR_800HZ
• BMI2_ACC_ODR_1600HZ

Measurement Range:

• BMI2_ACC_RANGE_2G ← best resolution
• BMI2_ACC_RANGE_4G
• BMI2_ACC_RANGE_8G
• BMI2_ACC_RANGE_16G (large motion)

Bandwidth (Noise vs Latency):

• BMI2_ACC_OSR4_AVG1 (lowest latency)
• BMI2_ACC_OSR2_AVG2
• BMI2_ACC_NORMAL_AVG4 ← recommended
• BMI2_ACC_CIC_AVG8
• BMI2_ACC_RES_AVG16
• BMI2_ACC_RES_AVG32
• BMI2_ACC_RES_AVG64
• BMI2_ACC_RES_AVG128 (lowest noise)

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🔄 Gyroscope Options

Output Data Rate (ODR):

• BMI2_GYR_ODR_25HZ
• BMI2_GYR_ODR_50HZ
• BMI2_GYR_ODR_100HZ ← recommended
• BMI2_GYR_ODR_200HZ
• BMI2_GYR_ODR_400HZ
• BMI2_GYR_ODR_800HZ
• BMI2_GYR_ODR_1600HZ
• BMI2_GYR_ODR_3200HZ

Measurement Range (deg/s):

• BMI2_GYR_RANGE_125
• BMI2_GYR_RANGE_250
• BMI2_GYR_RANGE_500
• BMI2_GYR_RANGE_1000
• BMI2_GYR_RANGE_2000 ← fast motion

Bandwidth:

• BMI2_GYR_OSR4_MODE (lowest latency)
• BMI2_GYR_OSR2_MODE
• BMI2_GYR_NORMAL_MODE ← recommended

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✅ Recommended Default Configuration

Sensor	ODR	Range	Bandwidth
Accelerometer	100 Hz	±2G	NORMAL_AVG4
Gyroscope	100 Hz	±2000 dps	NORMAL_MODE

📈 Output Units

Sensor	Unit
Accelerometer	g
Gyroscope	degrees/second (dps)
Temperature	°C

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🧪 Debug Tips

• Wrong CHIP_ID?
  Expected value: 0x24. Check wiring and power.

• SPI not working?
  CS must be LOW at power-up.

• No data?
  Confirm ODR is enabled and check loop timing.

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🚀 Next Steps / Advanced Features

• FIFO burst reads
• Interrupt-driven data ready
• Low-power mode
• Sensor fusion (external)
• Calibration routines

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📄 License

MIT License – This Arduino/C++ wrapper, examples, and documentation are released under the MIT License.

Bosch Sensortec Driver:

• This library uses the official Bosch Sensortec BMI2/BMI270 C driver, which is copyright © Bosch Sensortec GmbH and licensed under the BSD 3-Clause License.
• Bosch license terms must be retained when redistributing Bosch source/header files.
• This wrapper does not modify or replace Bosch’s license; it only adds Arduino integration.