RE: Use internal nRF52 pull-up w/ TWIM?

Krunal Desai — Thu, 09 Mar 2017 19:37:52 GMT

Perfect, thanks! I may add a high-value pull-down to both lines to enforce some kind of state before the nRF52 comes up and asserts state on its pins.

RE: Use internal nRF52 pull-up w/ TWIM?

bjorn-spockeli — Thu, 09 Mar 2017 13:54:26 GMT

Hi Krunal,

the internal pull-ups are enabled by default by the TWI Driver(nrf_drv_twi.c). If you take a look at the nrf_drv_twi_init(...) function you'll see that the GPIO pins are configured the following way

NRF_GPIO->PIN_CNF[p_config->scl] = SCL_PIN_INIT_CONF;
NRF_GPIO->PIN_CNF[p_config->sda] = SDA_PIN_INIT_CONF;

where SCL_PIN_INIT_CONF and SDA_PIN_INIT_CONF are defined as

#define SCL_PIN_INIT_CONF     ( (GPIO_PIN_CNF_SENSE_Disabled << GPIO_PIN_CNF_SENSE_Pos) \
                              | (GPIO_PIN_CNF_DRIVE_S0D1     << GPIO_PIN_CNF_DRIVE_Pos) \
                              | (GPIO_PIN_CNF_PULL_Pullup    << GPIO_PIN_CNF_PULL_Pos)  \
                              | (GPIO_PIN_CNF_INPUT_Connect  << GPIO_PIN_CNF_INPUT_Pos) \
                              | (GPIO_PIN_CNF_DIR_Input      << GPIO_PIN_CNF_DIR_Pos))
#define SDA_PIN_INIT_CONF        SCL_PIN_INIT_CONF

Best regards

Bjørn