Save data in NVM during POFWARN event

[Florent]

Hi,

I'm developing software for the nrf52832. However, I can't use the SDK of Nordic for several reasons. 

In the code, I would like to save a small amount of data in non-volatile memory (FLASH) when there is a power failure warning event. 

So far, I was using the NVMC for write and erase operations during normal run time of the device. However, I've just seen in the nrf52832 datasheet that the NVMC can not be used when there is a POFWARN event (i.e. the supply voltage is below POF). 

My questions are the following:

1.  Why can i not use the NVMC during the POFWARN event ?
2.  How can I save small urgent data in non-volatile memory during the POFWARN event  if I can't use the NVMC ? 

Thanks in advance for your response,

Best regards,

Florent

[run_ar]

1. Unfortunately, the POF will actually tell you that writes to NVMC is succesfull even if nothing has happened in case there is a power failure event . So I would not recommend that you use this, at least you cannot trust nvmc events in case you get a power failure event.

2. Consider using the regular comparator with 1.8v reference instead.

[Florent]

Hi run_ar,

Thank you for your quick reply.

1.  It's a pity that I can't use the NVMC during POF.
2. If I get it correclty, you mean to root a VDD track to one of the analog input pin & use the low power comparator of the nrf52832 to trigger another kind of event in which I would be able to store some data in NVM ?

Thanks in advance for your answer,

Best regards,

Florent

[run_ar]

1. I agree...

2. No, not the Low power comparator. If you use VDD as reference the reference would change with the voltage, so not sure if would ever trigger in time. Instead use the regular comparator. this can use an internal reference of 1.8 or 2.4 volts.