STM32配置IIC接口通信方式参考源码

最近在读取SHT3x系列sensor的温度和湿度，用到的是IIC接口。
顺便写了一下STM32的IIC接口。

这次配置的是STM32内部的IIC接口。

注意：读的时候，怎么发送Ack, 和 NAck信号，参考stm的设计文档。

#include "Dev_SHT3X.h"
#include "globalDef.h"
#include <stdio.h>


#define I2C1_OWN_ADDRESS7 0x0A
#define I2C_Speed          40000
#define SHT3X_ADDRESS      0x44

/* read out command */
#define CMD_READH_SHX      0x2c
#define CMD_READL_SHX      0x06

/**
* SHX device: IIC1
* PB6 - SCL
* PB7 - SDA
*/
static void IIC_gpioConfig(void)
{
    GPIO_InitTypeDef  GPIO_InitStructure;

    /* 使能与 I2C1 有关的时钟 */
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB,ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1,ENABLE);

    /* PB6-I2C1_SCL、PB7-I2C1_SDA*/
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_OD;     // 开漏输出
    GPIO_Init(GPIOB, &GPIO_InitStructure);
}

static void IIC_modeConfig(void)
{
    I2C_InitTypeDef  I2C_InitStructure;

    I2C_InitStructure.I2C_Mode = I2C_Mode_I2C; /* I2C 配置 */
    I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_2; /* 高电平数据稳定，低电平数据变化 SCL 时钟线的占空比 */
    I2C_InitStructure.I2C_OwnAddress1 = I2C1_OWN_ADDRESS7; /* setting master address. */
    I2C_InitStructure.I2C_Ack = I2C_Ack_Enable ; /* enable ack */
    I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit; /* 7-bit addressing mode */
    I2C_InitStructure.I2C_ClockSpeed = I2C_Speed; /* communication speed <= 400k */

    I2C_Init(I2C1, &I2C_InitStructure);
    I2C_Cmd(I2C1, ENABLE);
}


void SHT3X_InitDevice(void)
{
    IIC_gpioConfig();
    IIC_modeConfig();
}


void sht3x_readTempHumi(uint8_t* pBuffer, uint8_t NumByteToRead)
{
    while(I2C_GetFlagStatus(I2C1, I2C_FLAG_BUSY)); /* detect IIC busy */

    I2C_GenerateSTART(I2C1, ENABLE); /* Send START condition */

    /* Test on EV5 and clear it */
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));

    /* Send slave device address for write */
    I2C_Send7bitAddress(I2C1, (SHT3X_ADDRESS << 1), I2C_Direction_Transmitter);

    /* Test on EV6 and clear it */
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));

    /* Clear EV6 by setting again the PE bit */
    I2C_Cmd(I2C1, ENABLE);

    /* Send the device address to write to */
    I2C_SendData(I2C1, CMD_READH_SHX);

    /* Test on EV8 and clear it */
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED));

    /* Send the device address to write to */
    I2C_SendData(I2C1, CMD_READL_SHX);

    /* Test on EV8 and clear it */
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED));

//------------------------------------------------

    /* Send STRAT condition a second time */
    I2C_GenerateSTART(I2C1, ENABLE);

    /* Test on EV5 and clear it */
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));

    /* Send shx address for read */
    I2C_Send7bitAddress(I2C1, ((SHT3X_ADDRESS << 1) | 0x01), I2C_Direction_Receiver);

    /* Test on EV6 and clear it */
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED));

    /* While there is data to be read */
    while(NumByteToRead)
    {
        if(NumByteToRead == 1)
        {
            /* Disable Acknowledgement */
            I2C_AcknowledgeConfig(I2C1, DISABLE);

            /* Send STOP Condition */
            I2C_GenerateSTOP(I2C1, ENABLE);
        }

        /* Test on EV7 and clear it */
        if(I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED))
        {
            /* Read a byte from the EEPROM */
            *pBuffer = I2C_ReceiveData(I2C1);

            /* Point to the next location where the byte read will be saved */
            pBuffer++;

            /* Decrement the read bytes counter */
            NumByteToRead--;
        }
    }

    /* Enable Acknowledgement to be ready for another reception */
    I2C_AcknowledgeConfig(I2C1, ENABLE);
}



//-----------------------------------------------------------------------------
static float SHT3X_CalcTemperature(uint16_t rawValue)
{
    // calculate temperature [°C]
    // T = -45 + 175 * rawValue / (2^16-1)
    return 175.0f * (float)rawValue / 65535.0f - 45.0f;
}

//-----------------------------------------------------------------------------
static float SHT3X_CalcHumidity(uint16_t rawValue)
{
    // calculate relative humidity [%RH]
    // RH = rawValue / (2^16-1) * 100
    return 100.0f * (float)rawValue / 65535.0f;
}

void sht3x_testTask(void)
{
    uint8_t recBuffer[6];
    uint16_t rawdata;
    float fTemp, fHumi;

    sht3x_readTempHumi(&recBuffer[0], 6);
    rawdata = recBuffer[0];
    rawdata = (rawdata << 8) + recBuffer[1];
    fTemp = SHT3X_CalcTemperature(rawdata);

    rawdata = recBuffer[3];
    rawdata = (rawdata << 8) + recBuffer[4];
    fHumi = SHT3X_CalcHumidity(rawdata);

    enterCriticalSection();
    printf("T: %0.2f, H: %0.1f\r\n", fTemp, fHumi);
    exitCriticalSection();
}

#ifndef _DEV_SHT3X_H
#define _DEV_SHT3X_H

#include "bsp_iic.h"
#include "bsp_SysConfig.h"



extern void SHT3X_InitDevice(void);
extern void sht3x_testTask(void);


#endif /* _DEV_SHT3X_H */