RE: Set SPI pins to tri-state

MartinBL — Fri, 13 May 2016 14:33:41 GMT

You can put the SPI pins in the default configuration. This will set the pin in a high impedance mode. Set pin as input, disconnect input buffer, disconnect pull ups/downs, use standard drive, and disable pin sense mechanism. You can use nrf_gpio_cfg_default() which is defined as follow:

__STATIC_INLINE void nrf_gpio_cfg_default(uint32_t pin_number)
{
    nrf_gpio_cfg(
            pin_number,
            NRF_GPIO_PIN_DIR_INPUT,
            NRF_GPIO_PIN_INPUT_DISCONNECT,
            NRF_GPIO_PIN_NOPULL,
            NRF_GPIO_PIN_S0S1,
            NRF_GPIO_PIN_NOSENSE);
}

To test it you can try to connect the pin to VDD and measure any current flowing into the pin. In high impedance mode it should be less than 1uA.