7Semi_ICM20948

Arduino Library for ICM-20948 9-Axis Motion Sensor

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Overview

7Semi_ICM20948 is a lightweight Arduino library for the TDK ICM-20948 9-axis IMU.
It supports both I²C and SPI interfaces with flexible configuration, including DLPF, ODR, full-scale selection, and sensor gating.

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Features

• I²C (400 kHz+) and SPI (Mode 0) support
• Accelerometer, Gyroscope, Magnetometer, and Temperature readouts
• Built-in scale conversion to physical units (g, dps, µT, °C)
• DLPF (Digital Low-Pass Filter) configuration
• Adjustable output data rates (ODR)
• Self-test, decimation (DEC3), and averaging options

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🔌 Wiring

SPI Connection

Wiring (SPI - Arduino UNO)

• • SCLK → D13
• • MISO (SDO) → D12
• • MOSI (SDI) → D11
• • CS → D10
• • INT → D2, optional
• • 3V3 → 3.3V
• • GND → GND

Wiring (SPI - ESP32 VSPI)

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• • SCLK → GPIO18
• • MISO (SDO) → GPIO19
• • MOSI (SDI) → GPIO23
• • CS → GPIO5
• • INT → any GPIO, optional
• • 3V3 → 3.3V
• • GND → GND

I2C Connection

Wiring (I2C - Arduino UNO)

• • SCL → A5
• • SDA → A4
• • INT → D2, optional
• • 3V3 → 3.3V
• • GND → GND

Wiring (I2C - ESP32)

• • SCL → GPIO22
• • SDA → GPIO21
• • INT → any GPIO, optional
• • 3V3 → 3.3V
• • GND → GND

Notes

• Magnetometer (AK09916)

  • The magnetometer is connected internally to the ICM-20948 via an auxiliary I²C master interface.
  • It works automatically when you call readMag().
  • If your board exposes AUX_DA / AUX_CL (SDA/SCL) pins, you can also connect them to your MCU I²C bus and enable bypass mode.

• Voltage Levels

  • Always use 3.3 V logic.
  • The ICM-20948 is not 5 V tolerant unless your breakout includes level shifting.

• SPI Mode

  • The device operates in SPI Mode 0 (CPOL = 0, CPHA = 0).
  • SPI clock is 1000000 Hz.

• I²C Mode

  • Default address is 0x68; if AD0 = HIGH, it becomes 0x69.
  • Use imu.begin(Wire, 0x68) or imu.begin(Wire, 0x69) accordingly.

• Sensor Orientation

  • Axes follow the right-hand convention:
    • +X → right - left
    • +Y → forward - backward
    • +Z → up - down
  • Use invertAxes() if you need to match your board’s orientation.

• Temperature Output

  • The temperature sensor reports die temperature, not ambient.
  • Typical offset is around +10 °C compared to the environment.

• Power Notes

  • Typical active current: ~3.5 mA (Accel + Gyro)
  • Use setSensors() to disable unused sensors to save power.

• Best Practices

  • Always call applyBasicDefaults() after begin().
  • Add a short delay (~100 ms) after begin() before reading data.
  • For very stable readings, apply simple averaging in software (e.g. 10-sample moving average).

• Interface bring-up

  • SPI.begin() and Wire.begin() must match your board type.
  • On Arduino UNO / AVR: use default hardware pins only.
  • On ESP32: call SPIClass SPI_ESP32(VSPI); SPI_ESP32.begin(SCK, MISO, MOSI, CS); and
    Wire.begin(SDA, SCL); before imu.begin().