STM32硬件I2C调试

调试情况1

现象：主I2C发送数据而没有收到应答，则下一次不能正常发送数据

背景：主I2C每次应该都能正常发送数据

硬件：野火STM32-MINI，1主0从，SCL和SDA直接上拉

软件：按键触发中断，主I2C发送一次数据，中断优先级，按键最低，I2C最高，且主I2C中有TIMEOUT计时

void PB_K2_IRQ_HANDLER(void)
{
    if(EXTI_GetITStatus(PB_K2_EXTILINE) != RESET)
    {
        EXTI_ClearITPendingBit(PB_K2_EXTILINE);
        
        mini_i2c_write(0x22, 0x47);
        LED_D5_TOGGLE;
//        printf("Push button K2 clicked!
");
    }
}

#define PB_PREPRIO                        3
#define PB_SUBPRIO                        3

#define SLAVER_I2C_PRIPRIO                0
#define SLAVER_I2C_SUBPRIO                0

优先级分组均为2

void mini_uart_config(void)
{
    // structure define
    USART_InitTypeDef usart_struct;
    GPIO_InitTypeDef gpio_struct;
    NVIC_InitTypeDef nvic_struct;
    
    // clock enable
    DEBUG_UART_RCC_CMD(DEBUG_UART_RCC, ENABLE);
    GPIO_RCC_CMD(DEBUG_UART_GPIO_RCC, ENABLE);
    
    // GPIO initialization
    gpio_struct.GPIO_Mode = GPIO_Mode_AF_PP;
    gpio_struct.GPIO_Speed = GPIO_Speed_50MHz;
    gpio_struct.GPIO_Pin = DEBUG_UART_TX;
    GPIO_Init(DEBUG_UART_GPIO, &gpio_struct);
    
    gpio_struct.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    gpio_struct.GPIO_Pin = DEBUG_UART_RX;
    GPIO_Init(DEBUG_UART_GPIO, &gpio_struct);
    
    // NVIC    initialization
    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
    nvic_struct.NVIC_IRQChannel = DEBUG_UART_IRQ;
    nvic_struct.NVIC_IRQChannelPreemptionPriority = DEBUG_UART_PRIPRIO;
    nvic_struct.NVIC_IRQChannelSubPriority = DEBUG_UART_SUBPRIO;
    nvic_struct.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&nvic_struct);
    
    // USART initialization
    usart_struct.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;
    usart_struct.USART_Parity = USART_Parity_No;
    usart_struct.USART_StopBits = USART_StopBits_1;
    usart_struct.USART_WordLength = USART_WordLength_8b;
    usart_struct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    usart_struct.USART_BaudRate = DEBUG_UART_BAUDRATE;
    USART_Init(DEBUG_UART, &usart_struct);
    
    USART_Cmd(DEBUG_UART, ENABLE);
    
    USART_ITConfig(DEBUG_UART, USART_IT_RXNE, ENABLE);
}

void mini_i2c_write(uint8_t reg_addr, uint8_t wdata)
{
    uint32_t timeout;
    
    I2C_GenerateSTART(MASTER_I2C, ENABLE);
    timeout = I2C_TIMEOUT;
    while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_MODE_SELECT) == RESET)
    {
        if(timeout-- == 0)
        {
            I2C_GenerateSTOP(MASTER_I2C, ENABLE);
            break;
        }
    }
    
    // device address
    I2C_Send7bitAddress(MASTER_I2C, SLAVER_I2C_OWN_ADDR, I2C_Direction_Transmitter);
    timeout = I2C_TIMEOUT;
    while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED) == RESET)
    {
        if(timeout-- == 0)
        {
            I2C_GenerateSTOP(MASTER_I2C, ENABLE);
            break;
        }
    }
    
    I2C_SendData(MASTER_I2C, reg_addr);
    timeout = I2C_TIMEOUT;
    while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == RESET)
    {
        if(timeout-- == 0)
        {
            I2C_GenerateSTOP(MASTER_I2C, ENABLE);
            break;
        }
    }
    
    I2C_SendData(MASTER_I2C, wdata);
    timeout = I2C_TIMEOUT;
    while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == RESET)
    {
        if(timeout-- == 0)
        {
            I2C_GenerateSTOP(MASTER_I2C, ENABLE);
            break;
        }
    }
    
    I2C_GenerateSTOP(MASTER_I2C, ENABLE);
}

问题所在：主I2C在未收到ACK应答，会产生应答错误，SR1的AF位置1，在TIMEOUT时间后，上面的用户代码会调用I2C_GenerateSTOP(MASTER_I2C, ENABLE)函数，CR1的STOP为会被置位，导致出错

调试代码，用串口打印状态寄存器及控制寄存器的值

void mini_i2c_write(uint8_t reg_addr, uint8_t wdata)
{
    if((MASTER_I2C->SR1 != 0) || (MASTER_I2C->SR2 != 0))
    {
        printf("Master I2C SR1 is %x and SR2 is %x
", MASTER_I2C->SR1, MASTER_I2C->SR2);
        printf("Master I2C CR1 is %x and CR2 is %x
", MASTER_I2C->CR1, MASTER_I2C->CR2);
//        mini_i2c_config();
        MASTER_I2C->CR1 ^= 0x0200;
        printf("Master I2C SR1 is %x and SR2 is %x
", MASTER_I2C->SR1, MASTER_I2C->SR2);
        printf("Master I2C CR1 is %x and CR2 is %x
", MASTER_I2C->CR1, MASTER_I2C->CR2);
    }
    
    uint32_t timeout;
    
    I2C_GenerateSTART(MASTER_I2C, ENABLE);
    timeout = I2C_TIMEOUT;
    while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_MODE_SELECT) == RESET)
    {
        if(timeout-- == 0)
        {
            I2C_GenerateSTOP(MASTER_I2C, ENABLE);
            break;
        }
    }
    
    // device address
    I2C_Send7bitAddress(MASTER_I2C, SLAVER_I2C_OWN_ADDR, I2C_Direction_Transmitter);
    timeout = I2C_TIMEOUT;
    while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED) == RESET)
    {
        if(timeout-- == 0)
        {
            I2C_GenerateSTOP(MASTER_I2C, ENABLE);
            break;
        }
    }

经验证，重新初始化I2C或复位CR1的STOP可以排除对下次发送数据的干扰，串口打印消息如下

// Using mini_i2c_config()
Program started!
Master I2C SR1 is 400 and SR2 is 0
Master I2C CR1 is 601 and CR2 is 24
Master I2C SR1 is 0 and SR2 is 0
Master I2C CR1 is 401 and CR2 is 24
// Using MASTER_I2C->CR1 ^= 0x0200
Program started!
Master I2C SR1 is 400 and SR2 is 0
Master I2C CR1 is 601 and CR2 is 24
Master I2C SR1 is 400 and SR2 is 0
Master I2C CR1 is 401 and CR2 is 24

解决方案：使能主I2C错误中断，在中断中重新初始化I2C，并设置一个变量使主I2C发送函数提前终止

    nvic_struct.NVIC_IRQChannel = MASTER_I2C_ER_IRQ;
    NVIC_Init(&nvic_struct);

    I2C_ITConfig(MASTER_I2C, I2C_IT_ERR, ENABLE);

void MASTER_I2C_ER_IRQ_HANDLER(void)
{
    if(I2C_GetITStatus(MASTER_I2C, I2C_IT_AF) != RESET)
    {
        I2C_ClearITPendingBit(MASTER_I2C, I2C_IT_AF);
        
        mini_i2c_config();
        master_i2c_af = 1;
    }
}

void mini_i2c_write(uint8_t reg_addr, uint8_t wdata)
{
    master_i2c_af = 0;
    
    I2C_GenerateSTART(MASTER_I2C, ENABLE);
    while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_MODE_SELECT) == RESET);
    
    // device address
    I2C_Send7bitAddress(MASTER_I2C, SLAVER_I2C_OWN_ADDR, I2C_Direction_Transmitter);
    while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED) == RESET)
    {
        if(master_i2c_af)
        {
            master_i2c_af = 0;
            return;    // maybe there is a solution here
        }
    }
    
    I2C_SendData(MASTER_I2C, reg_addr);
    while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == RESET);
    
    I2C_SendData(MASTER_I2C, wdata);
    while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == RESET);
    
    I2C_GenerateSTOP(MASTER_I2C, ENABLE);
}