BMD300 I2C/TWI not working

Question

Hi,

I am trying to communicate with MLX90615 (here) sensor using BMD300. nRF52 DK is used to program the device. I am testing with a sample code which detects any I2C compatible device which is connected to SDA and SCL. There is no activity happening on SCL and SDA pins! SCL pin is LOW and SDA pin remains HIGH. The main code is given below.

 #include <stdio.h>
#include "boards.h"
#include "app_util_platform.h"
#include "app_uart.h"
#include "app_error.h"
#include "nrf_drv_twi.h"
#include "nrf_delay.h"

/*UART buffer size. */
#define UART_TX_BUF_SIZE 256
#define UART_RX_BUF_SIZE 1

#warning "!**** ARE YOU ABSOLUTELY SURE YOU HAVE CHOSEN THE CORRECT SCL AND SDA PINS? ****!"
#define DEVICE_SCL_PIN 6
#define DEVICE_SDA_PIN 7

nrf_drv_twi_t twi_instance = NRF_DRV_TWI_INSTANCE(0);

uint8_t device_address = 0; // Address used to temporarily store the current address being checked
bool device_found = false; 


/**
 * @brief UART events handler.
 */
static void uart_events_handler(app_uart_evt_t * p_event)
{
    switch (p_event->evt_type)
    {
        case APP_UART_COMMUNICATION_ERROR:
            APP_ERROR_HANDLER(p_event->data.error_communication);
            break;

        case APP_UART_FIFO_ERROR:
            APP_ERROR_HANDLER(p_event->data.error_code);
            break;

        default:
            break;
    }
}


/**
 * @brief UART initialization.
 */
static void uart_config(void)
{
    uint32_t                     err_code;
    const app_uart_comm_params_t comm_params =
    {
        RX_PIN_NUMBER,
        TX_PIN_NUMBER,
        RTS_PIN_NUMBER,
        CTS_PIN_NUMBER,
        APP_UART_FLOW_CONTROL_DISABLED,
        false,
        UART_BAUDRATE_BAUDRATE_Baud38400
    };

    APP_UART_FIFO_INIT(&comm_params,
                       UART_RX_BUF_SIZE,
                       UART_TX_BUF_SIZE,
                       uart_events_handler,
                       APP_IRQ_PRIORITY_LOW,
                       err_code);

    APP_ERROR_CHECK(err_code);
}

/**
 * @brief TWI events handler.
 */
void twi_handler(nrf_drv_twi_evt_t const * p_event, void * p_context)
{   
    switch(p_event->type)
    {
        case NRF_DRV_TWI_EVT_DONE:
            // If EVT_DONE (event done) is received a device is found and responding on that particular address
     //       printf("\r\n!****************************!\r\nDevice found at 7-bit address: %#x!\r\n!****************************!\r\n\r\n", device_address);
            device_found = true;
            break;
        case NRF_DRV_TWI_EVT_ADDRESS_NACK:
      //      printf("No address ACK on address: %#x!\r\n", device_address);
            break;
        case NRF_DRV_TWI_EVT_DATA_NACK:
      //      printf("No data ACK on address: %#x!\r\n", device_address);
            break;
        default:
            break;        
    }   
}

/**
 * @brief UART initialization.
 */
void twi_init (void)
{
    ret_code_t err_code;
    
    const nrf_drv_twi_config_t twi_config = {
       .scl                = DEVICE_SCL_PIN,
       .sda                = DEVICE_SDA_PIN,
       .frequency          = TWI_FREQUENCY_FREQUENCY_K100,
       .interrupt_priority = TWI0_CONFIG_IRQ_PRIORITY
    };
    
    err_code = nrf_drv_twi_init(&twi_instance, &twi_config, twi_handler, NULL);
    APP_ERROR_CHECK(err_code);
    
    nrf_drv_twi_enable(&twi_instance);
}

/**
 * @brief Function for main application entry.
 */
int main(void)
{
    nrf_gpio_cfg_output(9);
    nrf_gpio_pin_set(9);
  //  uart_config();
  //  printf("\033[2J\033[;H\r\n* Example to find TWI devices connected to \r\n* the TWI bus and their addresses\r\n\r\n");
    twi_init();
    
    uint8_t dummy_data = 0x07;
    // Itterate through all possible 7-bit TWI addresses
    for(uint8_t i = 0; i <= 0x7F; i++)
    {
      //  device_address = i;
        // Send dummy data. If a device is present on this particular address a TWI EVT_DONE event is 
        // received in the twi event handler and a message is printed to UART
        nrf_drv_twi_tx(&twi_instance, 0x5B, &dummy_data, 1, true);
        // Delay 10 ms to allow TWI transfer to complete and UART to print messages before starting new transfer
        nrf_delay_ms(10);
    }
    if(device_found)
    {
        // Blinke LED_1 rapidly if device is found
      
        
            nrf_gpio_pin_toggle(9);
            nrf_delay_ms(100);
        
    }
    else
    {
        
    }
}

What are the basic settings for TWI ? Is the initialisation correct? What are the recommended troubleshooting methods? Does the SCL pin out anything even if MLX90615 not detected?

regards, Vishnu