AT581X Example

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This example demonstrates the use of the espp::At581x driver to configure the AT581X 5.8 GHz radar presence/motion sensor (e.g. the MS58-3909S68U4 module on the ESP32-S3-BOX-3 sensor dock) over I2C.

It:

  • creates an I2C bus (default SDA=GPIO41, SCL=GPIO40 for the BOX-3 sensor dock),

  • constructs the At581x driver, which writes the configuration to the chip,

  • periodically changes the sensing distance (sensitivity) at runtime, and

  • attaches an espp::Interrupt to the radar output GPIO (CONFIG_EXAMPLE_RADAR_OUTPUT_GPIO, default GPIO21 on the BOX-3 dock) and prints presence/motion transitions. Set it to -1 to disable.

When the ESP32-S3-BOX-3 hardware profile is selected (the default on esp32s3), the example also uses the esp-box BSP to show the live radar status on the screen — a color-coded presence label plus the detection count and configured sensing distance. The radar is placed on I2C_NUM_1 in this mode so it doesn’t collide with the box’s internal I2C bus (I2C_NUM_0, GPIO8/18).

On the ESP32-S3-BOX-3 with the sensor dock attached, the defaults (SDA=41, SCL=40, radar output=21) should work as-is.

Configuration

Use idf.py menuconfig → Example Configuration to set the I2C pins and the radar output GPIO for your hardware.

Build and Flash

idf.py set-target esp32s3
idf.py build flash monitor

Output

The example logs the configuration it applies and, when the radar output GPIO is wired up, Radar presence DETECTED / Radar presence cleared as the sensor sees motion within its configured range.

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I (188) main_task: Calling app_main()
[at581x example/I][0.188]: Starting AT581X radar example
[At581x/I][0.190]: Writing config: freq=5800MHz, sensing_distance=700, gain=3, power=70uA, trigger_base=500ms, trigger_keep=1000ms, protect=1000ms, selfcheck=2000ms
[At581x/I][0.193]: Resetting RF frontend
[at581x example/I][0.196]: Watching radar output on GPIO 21
[at581x example/I][0.196]: Radar presence DETECTED
[Interrupt/W][0.197]: ISR service already installed, not installing again
W (199) ledc: the binded timer can't keep alive in sleep
[at581x example/I][2.322]: Radar presence cleared
[at581x example/I][5.057]: Radar presence DETECTED
[at581x example/I][7.838]: Radar presence cleared
[at581x example/I][14.645]: Radar presence DETECTED
[at581x example/I][16.186]: Radar presence cleared