Unable to use gpio reset pin as a gpio in nrf connect sdk

Question

Hi,

I am not able to use the gpio pin p0.18 as a gpio with nrf connect sdk. 
 I have tried to toggle the pin using "gpio_pin_toggle" and gpio_pin_set" functions but it is not working. (These functions returns 0) 
 
 I want to use it as a chip select pin for my peripheral, all other lines are working except the gpio p0.18. 
 I have disabled the reset functionality from the manuconf option. I have also tried to add CONFIG_GPIO_AS_PINRESET=n to the project config file but no luck. 
 
 As i can see in the zephyr.dts file, qdec interrupt pin also have the same number. (qdec is in disabled state in board.dts file). Would this be causing the problem ? 
 fyi, i have made sure the hardware is working by running sdk5 based code. 
 8863.zephyr.dts 
 I have tested it using the blinky example from zephyr samples. 
 Board: custom board based on nrf52840.

madblue · Accepted Answer

Thank you Heidi,

I have found that ' west flash ' is writing to UICR register to enable pin reset, which was causing the problem. 
 I have got it fixed by using, 
 nrfjprog -e && west flash --softreset, 
 Or by using nrfjprog --family nRF52 --program 
 
 I This looks like a serious issue and i wonder why does the west tool is updating the UICR registers. 
 Thanks for the support.

hmolesworth · Answer

Not sure if this helps, but the reset pin configuration is one-way; once set as a reset pin the only way to unset and use as a port pin is to do a flash erase all, and reprogram. This example is SDK not nRFConnect for nRF52832 but nRF52840 is similar with port P0.18 instead: /* Configure GPIO pads as pPin Reset pin if Pin Reset capabilities desired. If CONFIG_GPIO_AS_PINRESET is not defined, pin reset will not be available. One GPIO (see Product Specification to see which one) will then be reserved for PinReset and not available as normal GPIO. */ #if defined (CONFIG_GPIO_AS_PINRESET) if (((NRF_UICR->PSELRESET[0] & UICR_PSELRESET_CONNECT_Msk) != (UICR_PSELRESET_CONNECT_Connected << UICR_PSELRESET_CONNECT_Pos)) || ((NRF_UICR->PSELRESET[1] & UICR_PSELRESET_CONNECT_Msk) != (UICR_PSELRESET_CONNECT_Connected << UICR_PSELRESET_CONNECT_Pos))){ NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen << NVMC_CONFIG_WEN_Pos; // Write Enable while (NRF_NVMC->READY == NVMC_READY_READY_Busy){} NRF_UICR->PSELRESET[0] = 21; while (NRF_NVMC->READY == NVMC_READY_READY_Busy){} NRF_UICR->PSELRESET[1] = 21; while (NRF_NVMC->READY == NVMC_READY_READY_Busy){} NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos; // Read-only Enable while (NRF_NVMC->READY == NVMC_READY_READY_Busy){} // UICR changes require a reset to be effective NVIC_SystemReset(); } #endif

Unable to use gpio reset pin as a gpio in nrf connect sdk

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