nRF52 defines in ble_hrs example

Question

I'm using nRF52+SDK11.0.0+s132. In the ble_hrs PCA10040 example, the following are defined: 
 BLE_STACK_SUPPORT_REQD
BOARD_PCA10040
NRF52_PAN_12
NRF52_PAN_15
NRF52_PAN_20
NRF52_PAN_30
NRF52_PAN_31
NRF52_PAN_36
NRF52_PAN_51
NRF52_PAN_53
NRF52_PAN_54
NRF52_PAN_55
NRF52_PAN_58
NRF52_PAN_62
NRF52_PAN_63
NRF52_PAN_64
CONFIG_GPIO_AS_PINRESET
S132
NRF_LOG_USES_UART=1
SWI_DISABLE0
NRF52
SOFTDEVICE_PRESENT 
 I couldn't find NRF52_PAB_xx being used in the code. What are these? Also, if I'm not using pin21 for reset, all I need to do is remove CONFIG_GPIO_AS_PINRESET from the defines and I can use pin21 as a GPIO?

FormerMember · Accepted Answer

Yes, if you don't want to use pin 21 as GPIO, all you need to do is to remove CONFIG_GPIO_AS_PINRESET. As you can see in system_nrf52.c pin 21 will be configured as a pin reset if CONFIG_GPIO_AS_PINRESET is defined:

#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;
        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;
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
        NVIC_SystemReset();
    }
#endif

Unfortunately, I don't know why all the PANs are included in the projects, as I cannot either see that they are ever being used. I have reported this internally.