Decreasing Power Consumption to Minimum before entering __WFE

[joshuao]

Hi,

I'm using the NRF52840 with the nRF5SDK (v16.0).

For my product, I'd like to enter as low-power a sleep as possible, while still being able to wake up on the on board RTC periodically.

From reading, it appears that this is not a case for System OFF (As that cannot be woken up by the internal RTC), but for the System ON sleep, which is essentially the state during a "waiting for event".

During the rest of my code, I use many modules that are no doubt high-power: UART, TWI, I2S.

Is there a generic way to shut all of these down, ensuring that no events will come through, except the RTC one that I will set up after this.

It's fine in fact, if this leaves the libraries in a broken state, as I intend to restart the code upon waking up from the RTC anyway (although if there's a 0-effort way to not do that, I wouldn't).

There seems to be quite a few different Power Management sections to the SDK, but they all appear to deal with System OFF rather than setting up a good environment for a System ON sleep.

Do you have any advice?

[Jørgen Holmefjord]

Hi,

There is no standardized function that will power down all peripherals for you, as it is application dependant which ones should be powered down and which ones should be left running.

Most drivers/libraries has uninit functions that you can use to power down the peripheral before entering System ON mode. In many cases, the peripherals does not draw (much) current when only being enabled, but not active, but it would be no harm in uninitializing before sleep.

Best regards,
Jørgen

[joshuao]

Thanks Jørgen, I suppose I'd best actually measure some currents finally and have a go on your suggestions.