#include "main.h"
uint8_t BYTE_BUF[2];
//I2C GPIO初始化
void I2C_Init(void)
{
    rcu_periph_clock_enable(RCU_GPIOB); //使能GPIOB时钟
    // PB6--SCL,PB7--SDA.(I2C0)
    gpio_mode_set(GPIOB, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO_PIN_6 | GPIO_PIN_7);
    gpio_output_options_set(GPIOB, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_6 | GPIO_PIN_7);
    gpio_bit_set(GPIOB, GPIO_PIN_6 | GPIO_PIN_7);
}
//产生IIC起始信号
void IIC_Start(void)
{
    //SDA_OUT(); //sda线输出
    IIC_SDA_SET;
    IIC_SCL_SET;
    delay_us(4);
    IIC_SDA_RET; //START:when CLK is high,DATA change form high to low
    delay_us(4);
    IIC_SCL_RET; //钳住I2C总线，准备发送或接收数据
}
//产生IIC停止信号
void IIC_Stop(void)
{
    //SDA_OUT(); //sda线输出
    IIC_SCL_RET;
    IIC_SDA_RET; //STOP:when CLK is high DATA change form low to high
    delay_us(4);
    IIC_SCL_SET;
    IIC_SDA_SET; //发送I2C总线结束信号
    delay_us(4);
}
//等待应答信号到来
//返回值：1，接收应答失败
//        0，接收应答成功
uint8_t IIC_Wait_Ack(void)
{
    uint8_t ucErrTime = 0;
    //SDA_IN(); //SDA设置为输入
    IIC_SDA_SET;
    delay_us(1);
    IIC_SCL_SET;
    delay_us(1);
    while (READ_SDA)
    {
        ucErrTime++;
        if (ucErrTime > 250)
        {
            IIC_Stop();
            return 1;
        }
        delay_us(1);
    }
    IIC_SCL_RET; //时钟输出0
    return 0;
}
//产生ACK应答
void IIC_Ack(void)
{
    IIC_SCL_RET;
    //SDA_OUT();
    IIC_SDA_RET;
    delay_us(2);
    IIC_SCL_SET;
    delay_us(2);
    IIC_SCL_RET;
}
//不产生ACK应答
void IIC_NAck(void)
{
    IIC_SCL_RET;
    //SDA_OUT();
    IIC_SDA_SET;
    delay_us(2);
    IIC_SCL_SET;
    delay_us(2);
    IIC_SCL_RET;
}
//IIC发送一个字节
//返回从机有无应答
//1，有应答
//0，无应答
void IIC_Send_Byte(uint8_t txd)
{
    uint8_t t;
    //SDA_OUT();
    IIC_SCL_RET; //拉低时钟开始数据传输
    for (t = 0; t < 8; t++)
    {
        if ((txd & 0x80) >> 7)
            IIC_SDA_SET;
        else
            IIC_SDA_RET;
        txd <<= 1;
        delay_us(2); //对TEA5767这三个延时都是必须的
        IIC_SCL_SET;
        delay_us(2);
        IIC_SCL_RET;
        delay_us(2);
    }
}
//读1个字节，ack=1时，发送ACK，ack=0，发送nACK
uint8_t IIC_Read_Byte(unsigned char ack)
{
    unsigned char i, receive = 0;
    //SDA_IN(); //SDA设置为输入
    for (i = 0; i < 8; i++)
    {
        IIC_SCL_RET;
        delay_us(2);
        IIC_SCL_SET;
        receive <<= 1;
        if (READ_SDA)
            receive++;
        delay_us(1);
    }
    if (!ack)
        IIC_NAck(); //发送nACK
    else
        IIC_Ack(); //发送ACK
    return receive;
}

uint8_t LTC2451_NewConv(void)
{
    IIC_Start();
    IIC_Send_Byte(LTC2451_ADDR_W);
    if (IIC_Wait_Ack() != 0)
        return 1;
    IIC_Stop();
    return 0;
}

uint8_t LTC2451_ReadAdc(uint16_t *adc_value)
{
    uint8_t temp[2];
    IIC_Start();
    IIC_Send_Byte(LTC2451_ADDR_R);
    if (IIC_Wait_Ack() != 0)
        return 1;
    temp[0] = IIC_Read_Byte(1);
    temp[1] = IIC_Read_Byte(0);
    IIC_Stop(); //产生一个停止条件

    *adc_value = (temp[0] << 8) + temp[1];
    return 0;
}