Turning SPI peripheral on/off from PPI

RE: Turning SPI peripheral on/off from PPI

Stian Røed Hafskjold — Fri, 10 Feb 2017 15:33:53 GMT

Yes, high accuracy mode consumes about 8uA when activated. When using low accuracy mode (= PORT event), the PPI will not be able to distinguish between between which pin triggered the event. You have to use a software interrupt handler for this.

RE: Turning SPI peripheral on/off from PPI

cirlam — Thu, 02 Feb 2017 18:33:09 GMT

Thanks for both of your responses. You are correct - I was using GPIOTE events in High accuracy mode. I was under the impression that these events are not horrendous in terms of current draw: devzone.nordicsemi.com/.../ However, it sounds like this isn't correct?

I actually have multiple sensors presenting a data ready interrupt. Can PORT events be used in this case - I presume there is no way for PPI to be able to distinguish between which pin (and therefore which sensor has data ready) triggered the PORT event?

RE: Turning SPI peripheral on/off from PPI

Stian Røed Hafskjold — Thu, 02 Feb 2017 11:20:46 GMT

Roger Clark's answer is correct. It could be that the GPIOTE is in high accuracy mode. You should check out low accuracy mode and using the PORT event instead. And yes, you can use PPI to both start the TWI transaction and toggle a GPIO when it is done.

RE: Turning SPI peripheral on/off from PPI

Roger Clark — Tue, 31 Jan 2017 00:09:14 GMT

From what I understand, nRF52 power management of peripherals is supposed to automatically turn off devices when they are not being used.

Are you sure the problem is SPI inside the nRF52 and not your peripheral.

Also GPIOTE events in fast mode are known to take a lot of power.

I know on the nRF51 that for GPIOTE to operate in fast mode, that it requires the HF oscillator to run. Hence for low power operation on the nRF51, GPIOTE needs to be set to Port Mode.

From what I have read, GPIOTE event current is still high on the nRF52 (see devzone.nordicsemi.com/.../)

Also see this errata infocenter.nordicsemi.com/index.jsp