Enable Access Port Protection in code - compatible with all three revisions of the IC

[Alj28]

Hi,

I am working on a project that utilizes the nRF52832.

How to properly enable Access Port protection in the code, if I want to have a single firmware for all three revisions of the IC.

Currently, I have something like that:

#define NRF_IC_REVISION_1 (0x00000042) 
#define NRF_IC_REVISION_2 (0x00000045) 

static void enable_read_out_protection(void)
{
    uint32_t ic_variant = NRF_FICR->INFO.VARIANT;
    uint32_t build_code = ((ic_variant >> 8) & 0x000000FF);

    if ((NRF_IC_REVISION_1 != build_code) && (NRF_IC_REVISION_2 != build_code))
    {
        return;
    }

    // check if APPROTECT is already enabled.
    if (0xFFFFFF00 != NRF_UICR->APPROTECT)
    {
        // APPROTECT not set yet

        // program new value to APPROTECT
        nrf_nvmc_write_word((uint32_t)&(NRF_UICR->APPROTECT), 0xFFFFFF00);

        // trigger reset to apply new settings
        NVIC_SystemReset();
    }
}

Is the approach used to detect the revision of the IC ok?

[Simonr]

Okay, I see. Thank you for the explanation.

To answer your question, yes. If you write the word that locks the APPROTECT of older revisions, that should also lock revision 3 ICs. What makes you think it will be stuck in a reset loop?

Best regards,

Simon

[Alj28]

Mostly, because I do not have a sample of revision 3 at hand to simply try it out and validate the solution.
As I see, the nRF52 DK version 3.0.0 has  a QFAAG0 version of the IC. Maybe we will purchase a DK board and try the firmware on the board. As you said, better safe than sorry.

Thank you for your support.