M5Stack, the company that builds modular IoT solutions, brings us the TMOS PIR Unit which can be used for motion detection and human presence sensing.
PIR stands for Passive Infrared Sensor. A PIR sensor measures the amount of IR radiation emitted from an object. Humans, animals, and many other objects emit black body radiation.
The TMOS PIR Unit features the STHS34PF80 chip by STMicroelectronics which is an infrared motion and presence detection sensor that operates in wavelengths between 5 µm and 20 µm. The chip claims to work up to 4 meters and can distinguish between stationary and moving objects. M5Stack states the module should work reliably in measuring distances over 2 meters.

Feature of the TMOS PIR Unit:
- An 80-degree field of view. Any object within this field of view will be detected by the sensor.
- Measurement distance over 2 meters.
- Operating voltage: 3.6V to 5.5V.
- I2C communication.
- Contains an integrated silicon IR filter to reduce noise in measurements by allowing only infrared wavelengths to pass through.
- Programmable output data rate 0.25 Hz to 30 Hz.
- Local temperature sensor accuracy: ±0.3 °C.
- Infrared Sensitivity: 2000 LSB/°C.
- Product Dimensions: 32*24*8mm.
- Product Weight: 4.4g
The unit includes an SRV05-4 chip for ESD protection, an LDO voltage regulator that outputs 3.3V, and 2.2K resistors for the I2C bus. Here is the schematic of the TMOS PIR Unit :

The I2C hex address of the unit is 0x5A. The sensor can be easily wired with controllers from M5Stack such as the M5StickC PLUS2 ESP32 Mini IoT Development Kit which features the ESP32-PICO-V3-02 chip.
Arduino code examples for the TMOS PIR Unit can be found on its GitHub page. It is available to buy in the M5Stack store and is retailing for a price of $6.50 at the time of publishing this article. The package also includes a 20cm HY2.0-4P Grove cable for connection. It connects to ‘HY2.0-4P’ connectors which are used for connections in the M5Stack Unit system.
Also read: How to Interface Raspberry Pi Pico With PIR Motion Sensor – Send Email Alert (MicroPython).
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