NVMC driver wait_for_flash_ready

[JeanMBoones]

I have a question about the wait_for_flash_ready routine in the nrf_nvmc.c file.

    static inline void wait_for_flash_ready(void)
{
    while (NRF_NVMC->READY == NVMC_READY_READY_Busy) {;}
}

Can you tell me if this particular while loop can ever get stuck? Does it timeout after a certain time? If so, is there any way to detect that this timed out and the NVM controller was not able to complete the operation?

[Hung Bui]

Could you tell if you use softdevice ? access directly to NVMC is blocked when the softdevice is active.

NRF_NVMC->READY stay in NVMC_READY_READY_Busy if there isn't any activity. You need to trigger a NVMC task so the NRF_NVMC->READY can change to 1. If you don't have any activity, you will stuck inside that function.

[JeanMBoones]

I am not using the SoftDevice. I thought NRF_NVMC->READY == NVMC_READ_READY_Busy statement was true when NVM controller was busy performing an NVM operation? I would like to know if there is a possibility that something goes wrong in the hardware and this statement NRF_NVMC->READY == NVMC_READ_READY_Busy is always true and we get stuck in an infinite loop?

[Hung Bui]

Hi Jean,

I have to correct myself. My understanding now is that NRF_NVMC->READY stay in NVMC_READY_READY_Ready when there is no activity and when there is activity going on it will switch to NVMC_READY_READY_Busy. Sorry for the confusion.

So you shouldn't get stuck in that loop.

[JeanMBoones]

Yes. But could there be a scenario when this statement NRF_NVMC->READY == NVMC_READY_READY_Busyis always true due to some error in the hardware i.e. it always thinks there is some activity going on. Wouldn't we get stuck in an infinite loop? What happens then?

[Hung Bui]

The chip should never get stuck in that loop. It would be unrealistic to guarantee the chip will 100% operate as it should and will never fail, as you said hardware error can happen. But we haven't got any report from customers about any issue related to that, giving the fact that the chips have been out for 6 years and hundreds of million have been sold. Anyway, you can implement a watch dog timer just to be on the safe side that the device won't brick and can reset if anything happens.