STM32 硬件IIC接口总线

在网上总看到有人说STM32的硬件IIC不好用，可到底哪不好用，也一直没找到问题点。

最近有空看了一下STM32的硬件IIC，里面很多EV5/EV6等事件的概念是有些别扭，不过不影响使用。

写了一个简单的polling模式下的数据读写，也能正常实现功能。但是在单步调试时发现了一些问题，先上代码：

void     STM32F407_IIC_readNByte(u8 addr, u8 * pdata, u8 length)
{
    u8 i = 0;
    I2C_GenerateSTART(I2C1, ENABLE);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT)); //EV5

    I2C_Send7bitAddress(I2C1, 0xA0, I2C_Direction_Transmitter);
//    I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));  //EV6
    I2C_SendData(I2C1, addr);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTING));        //EV8
    I2C_GenerateSTART(I2C1, ENABLE);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));                //EV5
    I2C_Send7bitAddress(I2C1, 0xA0, I2C_Direction_Receiver);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED));    //EV6

    for(i = 0; i < length; i++)
    {
        if(i == 6)
        {
            while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED));        //EV7_1
            *pdata = I2C_ReceiveData(I2C1);
            I2C_AcknowledgeConfig(I2C1, DISABLE);
            I2C_GenerateSTOP(I2C1, ENABLE);
            pdata++;
        }
        else
        {
            while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED));        //EV7
            *pdata = I2C_ReceiveData(I2C1);
            pdata++;
        }
    }
    
}

上述代码第5行是在循环查询EV5事件是否发生，EV5事件是SB==1，可通过先读取SR1，在写DR寄存器来清除SB的状态，单步调试也是如此。
第9行是在循环查询EV6事件是否发生，EV6事件是ADDR==1，可通过先读取SR1，再读取SR2清除ADDR的状态。但是代码在全速运行时可正常执行，在单步调试时，发现还未读取SR1/SR2，ADDR的状态就已清0，导致第九行的while循环检测不到EV6事件，不知此问题是否是STM32硬件IIC的一个bug，但此问题不影响正常使用

一般IIC器件的读是可以连续读的，但写时一次最多只能写一个page，写下一个page，需要重新发送起始位，要写入的地址等，经测试，如下代码可实现正常读写（polling模式下）：

#include <sys.h>
#include "delay.h"
#include "STM32_IIC.h"

#define AT24C02_PAGE_SIZE     8

void STM32F407_IIC_Init()
{
    GPIO_InitTypeDef GPIO_InitStructure;
    I2C_InitTypeDef I2C_InitStructure;
    
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE);
    
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_9;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    GPIO_PinAFConfig(GPIOB, GPIO_PinSource8, GPIO_AF_I2C1);
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource9, GPIO_AF_I2C1);

    I2C_InitStructure.I2C_ClockSpeed = 100000;
    I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;
    I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;
    I2C_InitStructure.I2C_OwnAddress1 = 0x44;
    I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
    I2C_InitStructure.I2C_DutyCycle = 0;
    I2C_Init(I2C1, &I2C_InitStructure);
    I2C_AcknowledgeConfig(I2C1, ENABLE);
    I2C_StretchClockCmd(I2C1, DISABLE);
}

u8 STM32F407_IIC_randomReadByte(u8 addr)
{
    u8 retvalue = 0;
    I2C_GenerateSTART(I2C1, ENABLE);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));
    I2C_Send7bitAddress(I2C1, 0xA0, I2C_Direction_Transmitter);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));
    I2C_SendData(I2C1, addr);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTING));
    I2C_GenerateSTART(I2C1, ENABLE);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));
    I2C_Send7bitAddress(I2C1, 0xA0, I2C_Direction_Receiver);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED));
    I2C_AcknowledgeConfig(I2C1, DISABLE);
    while(!I2C_GetFlagStatus(I2C1, I2C_FLAG_RXNE));
    retvalue = I2C_ReceiveData(I2C1);
    I2C_GenerateSTOP(I2C1, DISABLE);
    return retvalue;
}

u8 STM32F407_IIC_readCurrentByte()
{
    u8 retvalue = 0;
    while(I2C_GetFlagStatus(I2C1, I2C_FLAG_BUSY));
    I2C_GenerateSTART(I2C1, ENABLE);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));
    I2C_Send7bitAddress(I2C1, 0xA0, I2C_Direction_Receiver);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED)); //EV6
    retvalue = I2C_ReceiveData(I2C1);
    I2C_AcknowledgeConfig(I2C1, DISABLE);
    while(!I2C_GetFlagStatus(I2C1, I2C_FLAG_RXNE));
    retvalue = I2C_ReceiveData(I2C1);
    I2C_GenerateSTOP(I2C1, DISABLE);
    return retvalue;
}

void STM32F407_IIC_randomWriteByte(u8 addr, u8 value)
{
    I2C_GenerateSTART(I2C1, ENABLE);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));
    I2C_Send7bitAddress(I2C1, 0xA0, I2C_Direction_Transmitter);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED)); //EV6
    I2C_SendData(I2C1, addr);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED));    
    I2C_SendData(I2C1, value);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED));    
    I2C_GenerateSTOP(I2C1, ENABLE);
}

void     STM32F407_IIC_readNByte(u8 addr, u8 * pdata, u8 length)
{
    u8 i = 0;
    I2C_GenerateSTART(I2C1, ENABLE);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT)); //EV5

    I2C_Send7bitAddress(I2C1, 0xA0, I2C_Direction_Transmitter);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));  //EV6
    I2C_SendData(I2C1, addr);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTING));        //EV8
    I2C_GenerateSTART(I2C1, ENABLE);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));                //EV5
    I2C_Send7bitAddress(I2C1, 0xA0, I2C_Direction_Receiver);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED));    //EV6

    for(i = 0; i < length; i++)
    {
        if(i == length - 2)
        {
            while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED));        //EV7_1
            *pdata = I2C_ReceiveData(I2C1);
            I2C_AcknowledgeConfig(I2C1, DISABLE);
            I2C_GenerateSTOP(I2C1, ENABLE);
            pdata++;
        }
        else
        {
            while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED));        //EV7
            *pdata = I2C_ReceiveData(I2C1);
            pdata++;
        }
    }
}


/* This function will not roll over if the program address is out of current page boundary */
void     STM32F407_IIC_writePage(u8 addr, u8 *pdata, u8 length)
{
    u8 i = 0;
    u8 remainToWrite = ((AT24C02_PAGE_SIZE - (addr % 8)) > length) ? length : (AT24C02_PAGE_SIZE - (addr % 8));
    
    I2C_GenerateSTART(I2C1, ENABLE);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT)); //EV5
    
    I2C_Send7bitAddress(I2C1, 0xA0, I2C_Direction_Transmitter);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));  //EV6
    I2C_SendData(I2C1, addr);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTING));        //EV8
    for(i = 0; i < remainToWrite; i++)
    {
        I2C_SendData(I2C1, *pdata);
        while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTING));        //EV8
        pdata++;
    }
    I2C_GenerateSTOP(I2C1, ENABLE);
}


/* This function will roll over if the program address is out of current page boundary */
//void     STM32F407_IIC_writePage(u8 addr, u8 *pdata, u8 length)
//{
//    u8 i = 0;
//    I2C_GenerateSTART(I2C1, ENABLE);
//    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT)); //EV5
//    
//    I2C_Send7bitAddress(I2C1, 0xA0, I2C_Direction_Transmitter);
//    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));  //EV6
//    I2C_SendData(I2C1, addr);
//    while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTING));        //EV8
//    for(i = 0; i < length; i++)
//    {
//        I2C_SendData(I2C1, *pdata);
//        while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTING));        //EV8
//        pdata++;
//    }
//    I2C_GenerateSTOP(I2C1, ENABLE);
//}

void     STM32F407_IIC_writeNByte(u8 addr, u8 *pdata, u8 length)
{
    u8 actualWriteByte = 0;
    while(length > 0)
    {
        actualWriteByte = ((AT24C02_PAGE_SIZE - (addr % 8)) > length) ? length : (AT24C02_PAGE_SIZE - (addr % 8));
        STM32F407_IIC_writePage(addr, pdata, length);
        addr += actualWriteByte;
        pdata += actualWriteByte;
        length -= actualWriteByte;
        delay_ms(5);
    }
}