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ADT7420: High accuracy digital I2C temperature sensor

Description

This sample application periodically (1Hz) measures the ambient temperature in degrees Celsius. The result is written to the console.

When configured in trigger mode the update interval is 5 s, and the sample maintains a ±1° C window around a recent temperature. As soon as the temperature goes outside the window an interrupt causes the application to display an event and update the upper and lower window boundaries.

References

Wiring

This sample uses the ADT7420 sensor controlled using the I2C interface. Connect Supply: VDD, GND and Interface: SDA, SCL and optionally connect the INT to a interrupt capable GPIO. The supply voltage can be in the 2.7V to 5.5V range. Depending on the baseboard used, the SDA and SCL lines require Pull-Up resistors.

Building and Running

This project outputs sensor data to the console. It requires an ADT7420 sensor. It should work with any platform featuring a I2C peripheral interface. It does not work on QEMU. In this example below the nRF52 DK board is used.

# From the root of the zephyr repository
west build -b nrf52dk_nrf52832 samples/sensor/adt7420
west flash

Sample Output

*** Booting Zephyr OS build zephyr-v2.1.0-538-g12b2ed2cf7c3  ***
device is 0x2000101c, name is ADT7420
[0:00:00.011]: temperature 21.203125 Cel
[0:00:01.015]: temperature 21.171875 Cel
[0:00:02.019]: temperature 21.171875 Cel
[0:00:03.023]: temperature 21.187500 Cel
[0:00:04.027]: temperature 21.140625 Cel

<repeats endlessly>