SDK 14.2 TWI disable internal pull-up resistor

Question

I am working with NRF52832 master with TWI slave device, however , since our board already has external pull-up resistors (10K) , how do I disable TWI internal pull up resistors ? I am using SDK14.2 
 
 Thank you in advance Ildefonso

Jared · Accepted Answer

Hi

The internal pull-up is set in the nrf_drv_twi_init() function in the nrf_drv_twi.c file:

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

SCL_PIN_INIT_CONF is 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))

Where the pull-up is set with the GPIO_PIN_CNF_PULL_Pullup with GPIO_PIN_CNF_PULL_Disabled. Replace GPIO_PIN_CNF_PULL_Pullup with GPIO_PIN_CNF_PULL_Disabled

Use the same method for changing the internal pull-up on the SDA pin,

Jared