How do I stop my UV sensor using the battery through VDD until I want it to? It's connected using TWI headers.

[John the novice]

I'm using the nRF52 DevKit with nrf52832 SoC. I connected a UV Sensor through the TWI interface (PINS 26 & 27, as well VDD and GND).

However, I fear it's using a lot of battery energy. So, I power down the TWI interface using the nrf_drv_twi_disable() and nrf_drv_twi_uninit() functions until I want to read the sensor. At which time I power it up again.

My question is, will calling these functions stop the sensor from using the battery? If not, please suggest how I can stop it from using any battery energy until I want to power it up and use it.

Thanks, and I'm looking forward to your response.

John

[Keith Wakeham]

Turing off the TWI interface only disables the interface on the nrf52832 chip. It very much depends on how the UV sensor operates to know if it's drawing current. So an evaluation cannot be made unless the type of uv sensor is known.

Usually the sensors have a shut down / sleep / low power command to them. This usually drops, but doesn't completely eliminate current draw. In some cases it gets it down to low microamp range. Except in extreme cases of power savings it's usually fine. Find out if it has it and send it before disabling your TWI interface.

You can alternatively control it's VDD supply via a fet.