Unkwon Resets after Long runtime ; Several Hours

[krisnov]

To whom it ma concern,

we observed Unkwon Resets after Long runtime ; Several Hours.

We use the NRF52840.

After the reset bit 1 in RESETREAS is detected .

BUT investigation with a scope shows no valid change for the physical reset pin.

WE do noticed some changes in the VDD voltage but within valid working range.

I stepped over the description of the NRF52832:

Is it possible this is valid for the NRF52840 as well?

AND this behavior sets bit 1 in RESETREAS ?

Regards

Kristijan

[Stian Røed Hafskjold]

Hi Kristijan,

Just to figure out if this RESETREAS =1 is valid or not, can you try to do a power cycle and read the RESETREAS register afterwards, and check if it is 1? I have seen previously that capacitance on the reset pin may cause the rise of the reset pin to lag behind the power on reset, so that a false pinreset is reported. 

Is pin reset in UICR enabled? Can you try to disable pin reset (erase UICR) and see if you still get these resets? Then we would know for sure if this is related to the reset pin or not.

The 52840 and 52832 are very similar so I would assume that the 300mV/300ms system reset is valid for 52840 as well.

Do you have any plots of the VDD fluctuations?

Are you reproducing these resets at normal indoor temperatures?

Best regards,
Stian