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

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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

1. void PB_K2_IRQ_HANDLER(void)
   
2. {
   
3.     if(EXTI_GetITStatus(PB_K2_EXTILINE) != RESET)
   
4.     {
   
5.         EXTI_ClearITPendingBit(PB_K2_EXTILINE);
   
6.         
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7.         mini_i2c_write(0x22, 0x47);
   
8.         LED_D5_TOGGLE;
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9. //        printf("Push button K2 clicked!\r\n");
   
10.     }
    
11. }

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1. #define PB_PREPRIO                        3
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2. #define PB_SUBPRIO                        3

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1. #define SLAVER_I2C_PRIPRIO                0
   
2. #define SLAVER_I2C_SUBPRIO                0

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优先级分组均为2

1. void mini_uart_config(void)
   
2. {
   
3.     // structure define
   
4.     USART_InitTypeDef usart_struct;
   
5.     GPIO_InitTypeDef gpio_struct;
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6.     NVIC_InitTypeDef nvic_struct;
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7.    
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8.     // clock enable
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9.     DEBUG_UART_RCC_CMD(DEBUG_UART_RCC, ENABLE);
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10.     GPIO_RCC_CMD(DEBUG_UART_GPIO_RCC, ENABLE);
    
11.    
    
12.     // GPIO initialization
    
13.     gpio_struct.GPIO_Mode = GPIO_Mode_AF_PP;
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14.     gpio_struct.GPIO_Speed = GPIO_Speed_50MHz;
    
15.     gpio_struct.GPIO_Pin = DEBUG_UART_TX;
    
16.     GPIO_Init(DEBUG_UART_GPIO, &gpio_struct);
    
17.    
    
18.     gpio_struct.GPIO_Mode = GPIO_Mode_IN_FLOATING;
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19.     gpio_struct.GPIO_Pin = DEBUG_UART_RX;
    
20.     GPIO_Init(DEBUG_UART_GPIO, &gpio_struct);
    
21.    
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22.     // NVIC    initialization
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23.     NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
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24.     nvic_struct.NVIC_IRQChannel = DEBUG_UART_IRQ;
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25.     nvic_struct.NVIC_IRQChannelPreemptionPriority = DEBUG_UART_PRIPRIO;
    
26.     nvic_struct.NVIC_IRQChannelSubPriority = DEBUG_UART_SUBPRIO;
    
27.     nvic_struct.NVIC_IRQChannelCmd = ENABLE;
    
28.     NVIC_Init(&nvic_struct);
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29.    
    
30.     // USART initialization
    
31.     usart_struct.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;
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32.     usart_struct.USART_Parity = USART_Parity_No;
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33.     usart_struct.USART_StopBits = USART_StopBits_1;
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34.     usart_struct.USART_WordLength = USART_WordLength_8b;
    
35.     usart_struct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    
36.     usart_struct.USART_BaudRate = DEBUG_UART_BAUDRATE;
    
37.     USART_Init(DEBUG_UART, &usart_struct);
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38.    
    
39.     USART_Cmd(DEBUG_UART, ENABLE);
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40.    
    
41.     USART_ITConfig(DEBUG_UART, USART_IT_RXNE, ENABLE);
    
42. }

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1. void mini_i2c_write(uint8_t reg_addr, uint8_t wdata)
   
2. {
   
3.     uint32_t timeout;
   
4.    
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5.     I2C_GenerateSTART(MASTER_I2C, ENABLE);
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6.     timeout = I2C_TIMEOUT;
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7.     while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_MODE_SELECT) == RESET)
   
8.     {
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9.         if(timeout-- == 0)
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10.         {
    
11.             I2C_GenerateSTOP(MASTER_I2C, ENABLE);
    
12.             break;
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13.         }
    
14.     }
    
15.    
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16.     // device address
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17.     I2C_Send7bitAddress(MASTER_I2C, SLAVER_I2C_OWN_ADDR, I2C_Direction_Transmitter);
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18.     timeout = I2C_TIMEOUT;
    
19.     while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED) == RESET)
    
20.     {
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21.         if(timeout-- == 0)
    
22.         {
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23.             I2C_GenerateSTOP(MASTER_I2C, ENABLE);
    
24.             break;
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25.         }
    
26.     }
    
27.    
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28.     I2C_SendData(MASTER_I2C, reg_addr);
    
29.     timeout = I2C_TIMEOUT;
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30.     while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == RESET)
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31.     {
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32.         if(timeout-- == 0)
    
33.         {
    
34.             I2C_GenerateSTOP(MASTER_I2C, ENABLE);
    
35.             break;
    
36.         }
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37.     }
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38.    
    
39.     I2C_SendData(MASTER_I2C, wdata);
    
40.     timeout = I2C_TIMEOUT;
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41.     while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == RESET)
    
42.     {
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43.         if(timeout-- == 0)
    
44.         {
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45.             I2C_GenerateSTOP(MASTER_I2C, ENABLE);
    
46.             break;
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47.         }
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48.     }
    
49.    
    
50.     I2C_GenerateSTOP(MASTER_I2C, ENABLE);
    
51. }

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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

1. void mini_i2c_write(uint8_t reg_addr, uint8_t wdata)
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2. {
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3.     if((MASTER_I2C->SR1 != 0) || (MASTER_I2C->SR2 != 0))
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4.     {
   
5.         printf("Master I2C SR1 is %x and SR2 is %x\r\n", MASTER_I2C->SR1, MASTER_I2C->SR2);
   
6.         printf("Master I2C CR1 is %x and CR2 is %x\r\n", MASTER_I2C->CR1, MASTER_I2C->CR2);
   
7. //        mini_i2c_config();
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8.         MASTER_I2C->CR1 ^= 0x0200;
   
9.         printf("Master I2C SR1 is %x and SR2 is %x\r\n", MASTER_I2C->SR1, MASTER_I2C->SR2);
   
10.         printf("Master I2C CR1 is %x and CR2 is %x\r\n", MASTER_I2C->CR1, MASTER_I2C->CR2);
    
11.     }
    
12.    
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13.     uint32_t timeout;
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14.    
    
15.     I2C_GenerateSTART(MASTER_I2C, ENABLE);
    
16.     timeout = I2C_TIMEOUT;
    
17.     while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_MODE_SELECT) == RESET)
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18.     {
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19.         if(timeout-- == 0)
    
20.         {
    
21.             I2C_GenerateSTOP(MASTER_I2C, ENABLE);
    
22.             break;
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23.         }
    
24.     }
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25.    
    
26.     // device address
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27.     I2C_Send7bitAddress(MASTER_I2C, SLAVER_I2C_OWN_ADDR, I2C_Direction_Transmitter);
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28.     timeout = I2C_TIMEOUT;
    
29.     while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED) == RESET)
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30.     {
    
31.         if(timeout-- == 0)
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32.         {
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33.             I2C_GenerateSTOP(MASTER_I2C, ENABLE);
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34.             break;
    
35.         }
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36.     }

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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

1. // Using mini_i2c_config()Program started!
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2. Master I2C SR1 is 400 and SR2 is 0
   
3. Master I2C CR1 is 601 and CR2 is 24
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4. Master I2C SR1 is 0 and SR2 is 0
   
5. Master I2C CR1 is 401 and CR2 is 24// Using MASTER_I2C->CR1 ^= 0x0200
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6. Program started!
   
7. Master I2C SR1 is 400 and SR2 is 0
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8. Master I2C CR1 is 601 and CR2 is 24
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9. Master I2C SR1 is 400 and SR2 is 0
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10. Master I2C CR1 is 401 and CR2 is 24

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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

  

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

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1.     I2C_ITConfig(MASTER_I2C, I2C_IT_ERR, ENABLE);

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1. void MASTER_I2C_ER_IRQ_HANDLER(void)
   
2. {
   
3.     if(I2C_GetITStatus(MASTER_I2C, I2C_IT_AF) != RESET)
   
4.     {
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5.         I2C_ClearITPendingBit(MASTER_I2C, I2C_IT_AF);
   
6.         
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7.         mini_i2c_config();
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8.         master_i2c_af = 1;
   
9.     }
   
10. }

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1. void mini_i2c_write(uint8_t reg_addr, uint8_t wdata)
   
2. {
   
3.     master_i2c_af = 0;
   
4.    
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5.     I2C_GenerateSTART(MASTER_I2C, ENABLE);
   
6.     while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_MODE_SELECT) == RESET);
   
7.    
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8.     // device address
   
9.     I2C_Send7bitAddress(MASTER_I2C, SLAVER_I2C_OWN_ADDR, I2C_Direction_Transmitter);
   
10.     while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED) == RESET)
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11.     {
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12.         if(master_i2c_af)
    
13.         {
    
14.             master_i2c_af = 0;
    
15.             return;    // maybe there is a solution here
    
16.         }
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17.     }
    
18.    
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19.     I2C_SendData(MASTER_I2C, reg_addr);
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20.     while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == RESET);
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21.    
    
22.     I2C_SendData(MASTER_I2C, wdata);
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23.     while(I2C_CheckEvent(MASTER_I2C, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == RESET);
    
24.    
    
25.     I2C_GenerateSTOP(MASTER_I2C, ENABLE);
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26. }

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