UCIR: write protection?

RE: UCIR: write protection?

bjorn-spockeli — Fri, 02 Mar 2018 08:20:11 GMT

rabarton:Correct, the ACL peripheral is only available on the nRF52840.

RE: UCIR: write protection?

rabarton — Mon, 26 Feb 2018 06:00:25 GMT

I don't see an ACL on the NRF52832. I guess this type of write protection for the UICR isn't available for the NRF52832?

RE: UCIR: write protection?

bjorn-spockeli — Thu, 26 Oct 2017 08:41:11 GMT

Happy to help :) I would appreciate if you could mark the answer as correct/accepted by clicking the check mark in the grey circle to the left of the answer.

RE: UCIR: write protection?

Reto — Thu, 26 Oct 2017 08:38:50 GMT

I was not aware of the ACL functionality. With ACL I should be able to write-protect the complete flash page where UICR registers are stored. Thanks Bjørn

RE: UCIR: write protection?

bjorn-spockeli — Thu, 26 Oct 2017 08:28:06 GMT

I think it should be possible to use the ACL peripheral to protect the UICR registers from being written to by the application.

RE: UCIR: write protection?

Reto — Thu, 26 Oct 2017 07:16:10 GMT

Thank you Bjørn! I am familiar with the flash concept (flash memory can only be written to when erased before and all bits are set to '1'). However, your answer clarified it for my (what nWRITE=2 means).

Short: the UCIR is a normal flash page, with the only difference that you have to erase it with ERASEUCIR or ERASEALL commands. AND: there is no way to protect the UCIR from unwanted write access from my custom FW code. Correct? I can read and write it from my FW code, but NOT erase?

Thanks! Reto

RE: UCIR: write protection?

bjorn-spockeli — Thu, 26 Oct 2017 06:57:34 GMT

Hi Reto,

the UICR registers are non-volatile memory, which means you can change bits from 1 to 0 in a register and you have to erase it, which sets it all back to 1s, again before you can clear the bits again.

So a nWRITE of 2 means that after initially writing a value to a UICR register you will be able to change 1s to 0s once before you need to erase it in order to write to it again.

As stated in the nRF52840 Product Specification, the only way to erase the UICR registers using ERASEUICR (which will erase all the UICR registers) or ERASEALL(erase the entire chip).

Best regards

Bjørn