[嵌入式]模拟I2C

I2C具体内容参考资料

https://blog.csdn.net/sternlycore/article/details/85600668
https://blog.csdn.net/qq_43460068/article/details/122409361

以下是在Atmel 300MHz下调试处的400KHz模拟I2C，延时函数需要根据实际内核进行设置

#define I2C_SDA_OUTPUT_DIR(pin)     ioport_set_pin_dir(pin, IOPORT_DIR_OUTPUT);
#define I2C_SDA_INPUT_DIR(pin)      ioport_set_pin_dir(pin, IOPORT_DIR_INPUT);
#define I2C_SDA_SET(pin)            ioport_set_pin_level(pin, IOPORT_PIN_LEVEL_HIGH);
#define I2C_SDA_CLR(pin)            ioport_set_pin_level(pin, IOPORT_PIN_LEVEL_LOW);
#define I2C_PIN_SDA(pin)            ioport_get_pin_level(pin)

#define I2C_SCL_SET(pin)            ioport_set_pin_level(pin, IOPORT_PIN_LEVEL_HIGH);
#define I2C_SCL_CLR(pin)            ioport_set_pin_level(pin, IOPORT_PIN_LEVEL_LOW);

#define BOARD_LOOPSPERMSEC   1300//1300//5126//51262
#define CONFIG_BOARD_LOOPSPER100USEC ((BOARD_LOOPSPERMSEC+5)/10)
#define CONFIG_BOARD_LOOPSPER10USEC  ((BOARD_LOOPSPERMSEC+50)/100)
#define CONFIG_BOARD_LOOPSPERUSEC    ((BOARD_LOOPSPERMSEC+500)/1000)
/*
 *@brief i2c delay  : 0.1us
 */
static void i2c_delay(uint32_t us)
{   
    volatile int i;

    while (us > 1000) {
        for (i = 0; i < BOARD_LOOPSPERMSEC; i++);
        us -= 1000;
    }
    while (us > 100) {
        for (i = 0; i < CONFIG_BOARD_LOOPSPER100USEC; i++);
        us -= 100;
    }
    while (us > 10) {
        for (i = 0; i < CONFIG_BOARD_LOOPSPER10USEC; i++);
        us -= 10;
    }
    while (us > 0) {
        for (i = 0; i < CONFIG_BOARD_LOOPSPERUSEC; i++);
        us--;
    }
}

/*
 *@brief i2c Start
 */
static void i2c_start(I2C_Object *object)
{
    I2C_SDA_OUTPUT_DIR(object->sda);
    I2C_SDA_SET(object->sda);
    I2C_SCL_SET(object->scl);
    i2c_delay(50);
    I2C_SDA_CLR(object->sda);
    i2c_delay(15);
}

/*
 *@brief i2c Stop
 */
static void i2c_stop(I2C_Object *object)
{
    I2C_SDA_OUTPUT_DIR(object->sda);
    I2C_SDA_CLR(object->sda);
    i2c_delay(15);
    I2C_SCL_SET(object->scl);
    i2c_delay(25);
    I2C_SDA_SET(object->sda);
    i2c_delay(25);
}

/*
 *@brief i2c Wait Acknowledge
 * 0:no ack   1:ack
 */
static uint8_t i2c_wait_ack(I2C_Object *object)
{
    uint8_t ret = 1;

    I2C_SDA_SET(object->sda);
    I2C_SDA_INPUT_DIR(object->sda);
    i2c_delay(10);
    I2C_SCL_SET(object->scl);
    i2c_delay(13);
    if(I2C_PIN_SDA(object->sda)){
        ret = 0;
    }
    I2C_SCL_CLR(object->scl);

    return ret; 
}

/*
 *@brief i2c Send Acknowledge
 */
static void i2c_send_ack(I2C_Object *object)
{
    I2C_SDA_OUTPUT_DIR(object->sda);
    I2C_SDA_CLR(object->sda);
    i2c_delay(13);
    I2C_SCL_SET(object->scl);
    i2c_delay(13);
    I2C_SCL_CLR(object->scl);    
}

/*
 *@brief i2c Send No Acknowledge
 */
static void i2c_send_noack(I2C_Object *object)
{
    I2C_SDA_OUTPUT_DIR(object->sda);
    I2C_SDA_SET(object->sda);
    i2c_delay(13);
    I2C_SCL_SET(object->scl);
    i2c_delay(13);
    I2C_SCL_CLR(object->scl);    
}

/*
 *@brief i2c Send Data
 */
static void i2c_send_data(I2C_Object *object, uint8_t data)
{
    uint8_t i = 8;
    
    I2C_SDA_OUTPUT_DIR(object->sda);
    while(i--)
    {
        I2C_SCL_CLR(object->scl);
        i2c_delay(15);
        if(data & 0x80)
        {
            I2C_SDA_SET(object->sda);
        }         
        else
        {
            I2C_SDA_CLR(object->sda);
        }
        
        i2c_delay(5);
        data <<= 1;
        I2C_SCL_SET(object->scl);
        i2c_delay(20);
    }   

    I2C_SCL_CLR(object->scl);
    i2c_delay(5); 
}

/*
 *@brief i2c Receive Data
 */
static uint8_t i2c_receive_data(I2C_Object *object)
{
    uint8_t i = 8;
    uint8_t data = 0;
    
    I2C_SDA_SET(object->sda);
    I2C_SDA_INPUT_DIR(object->sda);
    while(i--)
    {
        data <<= 1;
        I2C_SCL_CLR(object->scl);
        i2c_delay(13);
        I2C_SCL_SET(object->scl);
        i2c_delay(12);
        if(I2C_PIN_SDA(object->sda)) 
            data |= 0x01;
    }
    I2C_SCL_CLR(object->scl);
    
    return(data);    
}

/*
 *@brief Read Data
 */
uint8_t read_datas(I2C_Object *object, I2C_Transaction *transaction)
{
    uint8_t i;
    uint8_t *pdata = (uint8_t*)transaction->readBuf;

    i2c_start(object);
    i2c_send_data(object, transaction->slaveAddress<<1);
    if(i2c_wait_ack(object) == 0)
    {
        i2c_stop(object);
        return 0;
    }
    i2c_send_data(object, ((uint8_t *)transaction->writeBuf)[0]);
    if(i2c_wait_ack(object) == 0)
    {
        i2c_stop(object);
        return 0;
    }
    
    i2c_start(object);
    i2c_send_data(object, (transaction->slaveAddress<<1)|0x01);
    if(i2c_wait_ack(object) == 0)
    {
        i2c_stop(object);
        return 0;
    }
    for(i = 0; i < transaction->readCount; i++)
    {
        *pdata++ = i2c_receive_data(object);
        if(i < (transaction->readCount - 1))
            i2c_send_ack(object);
    }
    i2c_send_noack(object);
    i2c_stop(object);
    
    return 1;    
}

/*
 *@brief i2c Write one byte
 */
static uint8_t i2c_write_one_byte(I2C_Object *object, I2C_Transaction *transaction)
{    
    uint8_t *write_buf = (uint8_t*)transaction->writeBuf;

    i2c_start(object);
    i2c_send_data(object, transaction->slaveAddress<<1);
    if(i2c_wait_ack(object) == 0)
    {
        i2c_stop(object);
        return 0;
    }
    i2c_send_data(object, write_buf[0]);
    if(i2c_wait_ack(object) == 0)
    {
        i2c_stop(object);
        return 0;
    }

    i2c_send_data(object, write_buf[1]);
    if(i2c_wait_ack(object) == 0)
    {
        i2c_stop(object);
        return 0;
    }
    
    i2c_stop(object);
    
    return 1;    
}

创作打卡挑战赛

赢取流量/现金/CSDN周边激励大奖