Periodic current spikes while sleeping when twis is enabled

RE: Periodic current spikes while sleeping when twis is enabled

Stian Røed Hafskjold — Thu, 14 Mar 2019 14:40:14 GMT

Yes, that was for the nRF52840. Here is one for nRF52832:

devzone.nordicsemi.com/.../nrf52832_5F00_xxaa.hex

RE: Periodic current spikes while sleeping when twis is enabled

bearsh — Thu, 14 Mar 2019 07:49:01 GMT

Thanks for looking into this. The 10uA doesn't sound nice 😞 but at the end it explains the behavior.

I assume your hex file is for a nRF52840 DK? unfortunately I don't have that board, I only have a nRF52 DK. For the nRF52840 I have a DK and module from ublox.

RE: Periodic current spikes while sleeping when twis is enabled

Stian Røed Hafskjold — Thu, 07 Mar 2019 16:07:13 GMT

You should get about 10uA when TWIS is enabled and waiting for an interrupt. Testing I've done here seems to indicate that this corresponds to a refresh spike frequency of 350Hz. But there are chip to chip variations, so this might be higher as well. To see if this is chip to chip variation or the code you are running can you try to flash the attached hex file, and see what average current you get?

devzone.nordicsemi.com/.../nrf52840_5F00_xxaa.hex

Thanks

RE: Periodic current spikes while sleeping when twis is enabled

bearsh — Tue, 05 Mar 2019 14:08:29 GMT

so this means I have somewhere a small leak? in the first picture the average current is around 30uA. so it would also mean that the pins, once configured as twi, leak most of the 30uA because if disabled, the refresh interval is much higher?

RE: Periodic current spikes while sleeping when twis is enabled

Stian Røed Hafskjold — Tue, 05 Mar 2019 13:44:04 GMT

This is probably the chip operating in refresh mode. This is the lowest power consumption mode, and it works by regularly charging up a capacitor to provide power to the chip. When the chip consumes more current the spikes will occur more often because the capacitor is emptied faster.