> ## Documentation Index
> Fetch the complete documentation index at: https://dragonwingdocs-staging.qualcomm.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Sensors

The Dragonwing IQ-8275 EVK includes an on-board IMU and a temperature sensor, both connected to the real-time subsystem (RTSS) domain.

<Warning>
  Software support for the IMU and temperature sensors is not currently available.
</Warning>

| Reference Designator | Sensor Type | Protocol | MPN | Manufacturer |
| - | - | - | - | - |
| U97 | IMU sensor | I2C | ICM-42688 | TDK InvenSense |
| U109 | Temperature sensor | I2C (optional: SPI) | TMP411DQDGKRQ1 | Texas Instruments |

## Hardware Interfaces

**IMU (ICM-42688)**

* I²C bus on SAIL domain for register access (no software support currently)
* Interrupt GPIO for data-ready signaling

**Temperature Sensor (TMP411)**

* I²C bus on main domain (shared with fan controller)
* Optional SPI interface for faster data reads

<img src="https://mintcdn.com/qualcomm-staging/blZpKs_b9On5nj-y/archives/2.1/Ubuntu/images/peripheral-interfaces/sensor-connections.png?fit=max&auto=format&n=blZpKs_b9On5nj-y&q=85&s=93c76c917ffd4bcaa4508440edda0869" width="680" height="426" data-path="archives/2.1/Ubuntu/images/peripheral-interfaces/sensor-connections.png" />

<Note>
  Additional I2C, SPI, and UART interfaces are available on the LS1 low-speed header for connecting external sensors.
</Note>

## Usage

**IMU Sensor (ICM-42688)** — Provides 6-axis motion data (accelerometer + gyroscope) for robotics, navigation, and sensor fusion. Ideal for real-time applications requiring low-latency motion feedback.

**Temperature Sensor (TMP411)** — Monitors board and ambient temperature for thermal management. Used by fan control logic for dynamic cooling.

To use the temperature sensor with `lm-sensors`:

```shell theme={null}
sudo apt-get install lm-sensors
sensors-detect
sensors
```

## Troubleshooting

| Issue | Possible Cause | Solution |
| - | - | - |
| IMU not detected on I²C | Incorrect device tree or bus number | Verify `i2cdetect` output; check DTS configuration; confirm power rails |
| IMU interrupt not firing | GPIO misconfiguration | Check DTS interrupt mapping; verify GPIO polarity; test with `cat /proc/interrupts` |
| Temperature sensor not reporting | Driver not loaded or bus conflict | Load `tmp411` driver (`modprobe tmp411`); check fan controller sharing; confirm I²C address |
| Sensor read errors | Clock or power instability | Validate PMIC settings; check RTSS domain clocks; inspect `dmesg` |
| Ubuntu tools show no data | Missing kernel modules | Enable sensor drivers in kernel config; rebuild BSP; confirm `/sys/class/hwmon` |