52832 weird Reset pin behaviour

[Nick_RA]

I have a project which started life as ble_app_uart as a template which I've developed on the nRF52DK and is working fine. Now I am transferring it to my custom PCB.

When I first built upthe PCB nothing wold run, which looks like was because of the RESET pin unconnected so for troubleshooting I have a pullup resistor and pushbutton like this article NRF52 pin RESET

1. With the project as-is nothing would run unless I press the reset button. This doesn't sound right as I would expect the brownout / power-on reset to reset the CPU.

2. I've now removed CONFIG_GPIO_AS_PINRESET from the project preprocessor directives, now the project starts. BUT - I notice that the button still resets??? Is this correct, if so how do I disable reset on the pin?

Using Segger Embedded Studio BTW

[Susheel Nuguru]

2. I've now removed CONFIG_GPIO_AS_PINRESET from the project preprocessor directives, now the project starts. BUT - I notice that the button still resets??? Is this correct, if so how do I disable reset on the pin?

Which pin number are you using as reset on your custom board? We have this in our system_nrf52.c is as below

#if    defined (DEVELOP_IN_NRF52805) \
    || defined (DEVELOP_IN_NRF52810) \
    || defined (DEVELOP_IN_NRF52811) \
    || defined (DEVELOP_IN_NRF52832)
    #define RESET_PIN 21
#elif  defined (DEVELOP_IN_NRF52820) \
    || defined (DEVELOP_IN_NRF52833) \
    || defined (DEVELOP_IN_NRF52840)
    #define RESET_PIN 18
#elif  defined (NRF52805_XXAA) \
    || defined (NRF52810_XXAA) \
    || defined (NRF52811_XXAA) \
    || defined (NRF52832_XXAA) \
    || defined (NRF52832_XXAB)
    #define RESET_PIN 21
#elif  defined (NRF52820_XXAA) \
    || defined (NRF52833_XXAA) \
    || defined (NRF52840_XXAA)
    #define RESET_PIN 18
#else
    #error "A supported device macro must be defined."
#endif

Have you configured the right pin number to be connected to reset in your system_nrf52.c file to match your custom layout?

[Nick_RA]

Hi Thanks for the reply. I don't actually want to use any external reset pin. From the article I linked to above:

"If you dont want to use reset, just leave this pin floating - as long as you don't explicitly enable reset pin, it won't work. If you want to use it, don't leave it floating - use external pull-up."

Below are the preprocessor deinitions, so NRF52832_XXAA (pin 21) is currently defined. I would like to leave the pin floating, but I'm concerned that it is still an active reset. I don't want the pin active, or piulled up, as this is a power-sensitive application.

APP_TIMER_V2
APP_TIMER_V2_RTC1_ENABLED
FLOAT_ABI_HARD
INITIALIZE_USER_SECTIONS
NO_VTOR_CONFIG
NRF52
NRF52832_XXAA
NRF52_PAN_74
NRF_SD_BLE_API_VERSION=7
S112
SOFTDEVICE_PRESENT
MBEDTLS_CONFIG_FILE="nrf_crypto_mbedtls_config.h"

[Susheel Nuguru]

2. I've now removed CONFIG_GPIO_AS_PINRESET from the project preprocessor directives, now the project starts. BUT - I notice that the button still resets??? Is this correct, if so how do I disable reset on the pin?

Are you sure that you removed CONFIG_GPIO_AS_PINRESET and erased the whole chip before reprogramming it? it is important that you erase the whole flash including the UICR registers (nrfjprog -e   or   nrfjprog --recover).

For me it seems like you are reprogramming using --sectorerase which keeps the UICR value as is.

[Nick_RA]

Thanks that was the problem... erasing the entire flash sorted it.