RE: Cannot initialize QSPI (nRF52840 and Micron NOR Flash)

robca — Fri, 22 Oct 2021 03:30:31 GMT

Answering my own question: it was indeed a problem with having originally defined CONFIG_GPIO_AS_PINRESET. Once that is done, the pin is always pulled up high and even if redefined as a GPIO or for QSPI, it won't work (with no error notification)

What I didn't realize, is that the setting is persisted in UICR (which makes sense in hindsight, as most things do 🙂). So once an image with CONFIG_GPIO_AS_PINRESET is flashed on the chip, pin P0.18 will not work for anything else anymore, until the UICR data is erased

So, after removing CONFIG_GPIO_AS_PINRESET, I also needed to erase UICR, either with nrfjprog or the Erase All function in the GUI Nordic Prgrammer.

Problem solved, QSPI now initializes as expected