NRF51822之IIC(MEMS_LIS2DH12)

在上篇介绍了OLED的II以写操作为主，没有进行读取操作。所以在现再补充读取的操作。

我在此以LIS2DH为例子

uint8_t temp;
lis2dh_read_registers(LIS2DH_WHO_AM_I,&temp,);

我们现在操作的寄存器为who_am_i时序如下

好了现在贴上主要代码

#define MEMS_LIS2DH_ADDR         (0x30U>>1)

#define LIS2DH_WHO_AM_I           0x0F  

#define MEMS_TWI_TIMEOUT          5000 

static const nrf_drv_twi_t m_twi_mems_lis2ds12 = NRF_DRV_TWI_INSTANCE();//需要在nrf_drv_config.h文件中 #define TWI1_ENABLED 1

volatile static bool twi_tx_done = false;
volatile static bool twi_rx_done = false;

void mems_lis2dh12_twi_handler(nrf_drv_twi_evt_t const * p_event, void * p_context)
{   
    ret_code_t err_code;
    
    switch(p_event->type)
    {
        case NRF_DRV_TWI_RX_DONE:
            twi_rx_done = true;
            break;
        case NRF_DRV_TWI_TX_DONE:
            twi_tx_done = true;
            break;
        default:
            break;        
    }   
}

void bsp_lis2dh12_init(void)
{
    ret_code_t err_code;

    const nrf_drv_twi_config_t twi_mems_lis2dh12_config =
    {
        .scl                = MEMS_LIS2DH12_I2C_SCL_PIN,
        .sda                = MEMS_LIS2DH12_I2C_SDA_PIN,
        .frequency          = NRF_TWI_FREQ_100K,
        .interrupt_priority = APP_IRQ_PRIORITY_LOW
    };

    err_code = nrf_drv_twi_init(&m_twi_mems_lis2dh12, &twi_mems_lis2dh12_config, mems_lis2dh12_twi_handler, NULL);
    APP_ERROR_CHECK(err_code);

    nrf_drv_twi_enable(&m_twi_mems_lis2dh12);

    nrf_gpio_pin_clear(MEMS_LIS2DH12_SD0_PIN);
    nrf_gpio_cfg_output(MEMS_LIS2DH12_SD0_PIN);

    nrf_gpio_pin_set(MEMS_LIS2DH12_CS_PIN);
    nrf_gpio_cfg_output(MEMS_LIS2DH12_CS_PIN);

}

uint32_t lis2dh12_write_register(uint8_t reg_param, uint8_t data_param)
{
    uint32_t err_code;
    uint32_t timeout = MEMS_TWI_TIMEOUT;

    uint8_t packet[2] = {reg_param, data_param};

    err_code = nrf_drv_twi_tx(&m_twi_mems_lis2dh12, MEMS_LIS2DH12_ADDR, packet, 2, false);
    
    if(err_code != NRF_SUCCESS)
    {
        return err_code;    
    } 

    while((!twi_tx_done) && --timeout);
    
    if(!timeout)
    {
        return NRF_ERROR_TIMEOUT;    
    } 

    twi_tx_done = false;

    return err_code;
}

uint32_t lis2dh12_read_registers(uint8_t reg_param, uint8_t * p_data, uint32_t length)
{
    uint32_t err_code;
    uint32_t timeout = MEMS_TWI_TIMEOUT;

    err_code = nrf_drv_twi_tx(&m_twi_mems_lis2dh12, MEMS_LIS2DH12_ADDR, &reg_param, 1, false);
    if(err_code != NRF_SUCCESS) 
    {
        return err_code;    
    }

    while((!twi_tx_done) && --timeout);
    
    if(!timeout) 
    {
        return NRF_ERROR_TIMEOUT;    
    }
    
    twi_tx_done = false;

    err_code = nrf_drv_twi_rx(&m_twi_mems_lis2dh12, MEMS_LIS2DH12_ADDR, p_data, length, false);

                          
    if(err_code != NRF_SUCCESS) 
    {
        return err_code;
    }

    timeout = MEMS_TWI_TIMEOUT;
    
    while((!twi_rx_done) && --timeout);
    
    if(!timeout) 
    {
        return NRF_ERROR_TIMEOUT;
    }
    
    twi_rx_done = false;

    return err_code;
}