Partial flash erase and Softdevice possible?

[rgrr2]

Hello

I have a power constraint device.  Limit is not the total charge of a battery or so.  Limit is the peak current.

Available (peak) current is around 4mA (@1.8V), current peaks required e.g. for radio are buffered thru capacitors.

Everything is working except flash page erase.  This is because flash erase consumes around 6mA@3V and takes 85ms.  This is beyond the capacity of the Cs.  And this is limited due to Ex constraints.

Idea is to use partial flash erase to spread the consumption used for flash erasure so that the peak current is kept as small as possible.

Is there any Softdevice API to do this?  Any chance to bypass the Softdevice?  Any chance that this will be implemented in the next Softdevice version?

Thanks for help

Hardy

[bjorn-spockeli]

Hi Hardy, 

do you mean partially erasing a page, e.g. erasing the page in 1kB chunks instead of the entire page of 4kB in one go?

Best regards

Bjørn

[rgrr2]

Hi Björn,

was not aware that erasing in 1KByte chunks is possible (is it?).  I´m talking about the partial erase feature of the nRF52840: this splits the 85ms erase time into "n" smaller "m" ms-intervals, where "n" x "m" >= 85ms.

This would give the capacitors time to recharge and thus allows flash page erase without violation of our power constraints.

Regards

Hardy

[bjorn-spockeli]

Hi Hardy, 

No, that was just an example.

I forgot to ask which nRF52 device you are using? Since you were referring to the nRF52840, I assume that you're using that. Yes,  we do support partial page erases on the nRF52840 , nRF52833,  nRF52811 and nRF52810, see Partial erase of a page in flash. 

I do not think there is any SD API to use this feature of the NVMC, but you should be able to do this in a Timeslot. See Concurrent multiprotocol implementation using the Radio Timeslot API in the S140 SoftDevice Specification.

Best regards

Bjørn

[rgrr2]

Thanks Björn, for your suggestion with the timeslot API (which corresponds to my personal findings).

Would be great, if the SD API would be somehow enhanced to support partial erase of flash pages.  I don't think, that I'm the only one with this problem.

Regards Hardy

PS: MCU type is tagged on the right side, so I did not mention it again in the message body ;-)