Read LPS22HB Pressure sensor values with TWI on NRF52840

Question

I am trying to integrate a pressure sensor with our system and Nordic has libraries for LPS22HB sensor. I ordered STEVAL-MET001V1 from ST and try to modify the TWI-sensor examples under SDK15.2 peripherals examples, but only got incorrect readings. I also looked into Thingy 52 pressure sensing codes and tried with drv_lps22hb library, but get all 0 readings. There is another library lps22hb in the SDK but it seems to be harder to work with (sorry I am still learning). I have pasted some of the key codes here and wondering what is the problem. I don't understand what the set_mode() function does in the example, but I keep it anyhow. I just need a simple reading function to get the data whenever I call. Thank you for your help.

By the way, for LPS22HB, there are three addresses 0x28, 0x29 and 0x2A for pressure, two addresses 0x2B and 0x2C for temperature according to ST's documents.

/* TWI instance ID. */
#define TWI_INSTANCE_ID     0

/* Common addresses definition for temperature sensor. */
#define LM75B_ADDR         0x5DU// (0x90U >> 1)

#define PRESS_OUT_XL_REG    0x28U
#define PRESS_OUT_L_REG      0x29U
#define PRESS_OUT_H_REG      0x2AU
#define TEMP_OUT_L_REG     0x2BU
#define TEMP_OUT_H_REG       0x2CU
/* Mode for LM75B. */
#define NORMAL_MODE 0U

/* Indicates if operation on TWI has ended. */
static volatile bool m_xfer_done = false;
/* TWI instance. */
static const nrf_drv_twi_t m_twi = NRF_DRV_TWI_INSTANCE(TWI_INSTANCE_ID);

void LM75B_set_mode(void)
{
    ret_code_t err_code;

    /* Writing to LM75B_REG_CONF "0" set temperature sensor in NORMAL mode. */
    uint8_t reg[2] = {PRESS_OUT_XL_REG, NORMAL_MODE};
    err_code = nrf_drv_twi_tx(&m_twi, LM75B_ADDR, reg, sizeof(reg), false);
    APP_ERROR_CHECK(err_code);
    while (m_xfer_done == false);

    /* Writing to pointer byte. */
    reg[0] = PRESS_OUT_XL_REG;
    m_xfer_done = false;
    err_code = nrf_drv_twi_tx(&m_twi, LM75B_ADDR, reg, 1, false);
    APP_ERROR_CHECK(err_code);
    while (m_xfer_done == false);
}

void twi_init (void)
{
    ret_code_t err_code;

    const nrf_drv_twi_config_t twi_lm75b_config = {
       .scl                = ARDUINO_SCL_PIN,
       .sda                = ARDUINO_SDA_PIN,
       .frequency          = NRF_DRV_TWI_FREQ_100K,
       .interrupt_priority = APP_IRQ_PRIORITY_HIGH,
       .clear_bus_init     = false
    };

    err_code = nrf_drv_twi_init(&m_twi, &twi_lm75b_config, twi_handler, NULL);
    APP_ERROR_CHECK(err_code);

    nrf_drv_twi_enable(&m_twi);
    
    static uint32_t reg_read(uint8_t reg_addr, uint8_t * p_reg_val)
{
    m_xfer_done = false;

    uint32_t err_code;

    err_code = nrf_drv_twi_tx( &m_twi,
                               LM75B_ADDR,
                               &reg_addr,
                               1,
                               false );
       while (m_xfer_done == false);
            m_xfer_done = false; 
    err_code = nrf_drv_twi_rx( &m_twi,
                               LM75B_ADDR,
                               p_reg_val,
                               sizeof(p_reg_val));
    APP_ERROR_CHECK(err_code);
    return NRF_SUCCESS;
}

uint32_t lps22hb_pressure_get()
{
    uint32_t err_code;
    uint8_t  press_xl;
    uint8_t  press_l;
    uint8_t  press_h;
    uint8_t  temp_l;
    uint8_t  temp_h;
    uint32_t pressure;
    err_code = reg_read(PRESS_OUT_XL_REG, &press_xl);

    err_code = reg_read(PRESS_OUT_L_REG, &press_l);

    err_code = reg_read(PRESS_OUT_H_REG, &press_h);
    err_code = reg_read(TEMP_OUT_L_REG, &temp_l);

    err_code = reg_read(TEMP_OUT_H_REG, &temp_h);

    pressure = ((uint32_t)press_h << 16) + ((uint32_t)press_l << 8) + press_xl; // To calculate p(hPa) = *p_pressure(LSB) / 4096(LSB/hPa).
    NRF_LOG_INFO("Pressure: %d hPa.", pressure/4096);
    return NRF_SUCCESS;
}

/**
 * @brief Function for main application entry.
 */
int main(void)
{
    APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
    NRF_LOG_DEFAULT_BACKENDS_INIT();

    NRF_LOG_INFO("\r\nTWI sensor example started.");
    NRF_LOG_FLUSH();
    twi_init();
    LM75B_set_mode();

    while (true)
    {
        nrf_delay_ms(1000);

        do
        {
            __WFE();
        }while (m_xfer_done == false);

       lps22hb_pressure_get();
        NRF_LOG_FLUSH();
    }
}
}