Sleepy Thread Device with a BME280 sensor on a Nordic nRF52840 Dongle (PCA10059). Programmed with nRF Connect for Desktop/Zephyr.
As there is no support for OpenThread in Arduino, I'm trying my luck with the Nordic nRF Connect SDK/Zephyr. After struggling with the new concepts in Zephyr (device tree and overlay files), here is the first working example. It sends a JSON datagram with battery voltage, temperature, humidity and air pressure data from a BME280 I2C sensor over COAP/UDP and goes to sleep for 60 seconds.
Giving up on low power with the Zephyr SDK and device tree drivers. It's just not possible with its core concept of a device tree.
- the i2c bus and the device (sensor) is exclusively initialized during boot.
- there is no way to power-up/initialize a sensor device during runtime
- there is no way to de-initialize/power-down a sensor device during runtime
So I'm trying brute force methods:
- only use the i2c bus as a device from the device tree
- directly use the sensor with i2c commands and register voodoo
- the sensor can now be powered and switched off by a GPIO pin.
- deep sleep current is now 12µA
PPK2 measurement over a full 1 minute cycle (Nordic nRF52840 Dongle, BME280)
