Adafruit Tag Reader Example not working with certain RST and IRQ pin

[shockline]

I am trying to run adafruit_tag_reader example on nRF52840 DK.

Problem :

If these are my pins in sdk_config.h it works fine

#ifndef PN532_RESET
#define PN532_RESET NRF_GPIO_PIN_MAP(1, 13)
#endif

#ifndef PN532_IRQ
#define PN532_IRQ NRF_GPIO_PIN_MAP(1, 14)
#endif

Whereas this doesn't work.

#ifndef PN532_RESET
#define PN532_RESET NRF_GPIO_PIN_MAP(0, 9)
#endif

#ifndef PN532_IRQ
#define PN532_IRQ NRF_GPIO_PIN_MAP(0, 10)
#endif

[Vidar Berg]

Hi,

These pins are not connected to the Arduino pin headers by default, but to the nordic NFC connector, see NFC antenna interface. 

[shockline]

All pins that can be configured as input pins are valid for IRQ and Reset. Right ?

If I am making my custom board then can I configure 0.09 and 0.10 as IRQ and Reset ?

[Vidar Berg]

The NFC pins may be used as general-purpose IOs, but it may result in higher leakage current as noted here: 

input/output), and some increased leakage current between the two pins is to be expected if they are used in GPIO mode, and are driven to different logical values. To save power, the two pins should always be set to the same logical value whenever entering one of the device power saving modes. For details, refer to I_{NFC_LEAK} in the Electrical Specification of GPIO — General purpose

[shockline]

This worked for me.

From https://infocenter.nordicsemi.com/index.jsp?topic=%2Fug_nrf52840_dk%2FUG%2Fnrf52840_DK%2Fhw_nfc_if.html&cp=3_0_4_7_10

When using SEGGER Embedded Studio, go to Project > Edit Options > Code > Preprocessor > Preprocessor Definitions and add the CONFIG_NFCT_PINS_AS_GPIOS variable.