2018年09月09日 | STM32F103C8T6单片机通过I2C库函数来读写24C02存储器

电路连接：SCL和SDA分别接到PB6和PB7上，并都外接上10kΩ上拉电阻。

电路板如下图所示：

最左边的4个排针接的是电源和串口。

由于板上没有任何外部晶振，所以在Keil中建好工程后， 要将RTE/Device/STM32F103C8/system_stm32f10x.c中的SYSCLK_FREQ_72MHz的定义注释掉，防止SystemInit函数打开HSE晶振。

#if defined (STM32F10X_LD_VL) || (defined STM32F10X_MD_VL) || (defined STM32F10X_HD_VL)

/* #define SYSCLK_FREQ_HSE    HSE_VALUE */

 #define SYSCLK_FREQ_24MHz  24000000

#else

/* #define SYSCLK_FREQ_HSE    HSE_VALUE */

/* #define SYSCLK_FREQ_24MHz  24000000 */ 

/* #define SYSCLK_FREQ_36MHz  36000000 */

/* #define SYSCLK_FREQ_48MHz  48000000 */

/* #define SYSCLK_FREQ_56MHz  56000000 */

/* #define SYSCLK_FREQ_72MHz  72000000 */

#endif

板子有两种程序下载方式。一种是通过J-Link仿真器，在Keil中下载。另一种是按下板上的白色开关，将BOOT0拉高（BOOT1=PB2必须通过10kΩ的电阻接地），然后用STMicroelectronics的FlashLoader通过串口1下载编译好的hex文件。

板上LED灯串联的电阻是500Ω左右（由两个1kΩ的电阻并联而成），接到了PA8上，高电平点亮，本实验中没有用到。

复位电路所用的电容是0.1μF 50V的电解电容（104），是51/AVR的单片机所用的10μF的1%。

【程序1：普通方式】

#include

#include

int fputc(int ch, FILE *fp)

{

if (fp == stdout)

{

if (ch == '\n')

{

while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);

USART_SendData(USART1, '\r');

}

while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);

USART_SendData(USART1, ch);

}

return ch;

}

// 发送开始信号和从机地址(传输模式)

void start(void)

{

if (I2C1->SR1 || I2C1->SR2)

printf("error!\n");

restart:

I2C_GenerateSTART(I2C1, ENABLE);

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT) == ERROR); // 等待开始信号发送完毕

I2C_SendData(I2C1, 0xa0); // 从机地址(传输模式)

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED) == ERROR) // 等待从机确认

{

if (I2C_GetFlagStatus(I2C1, I2C_FLAG_AF) == SET)

{

// 若从机未响应, 则重试

// 执行了写操作后需要等待一段时间才能执行其他命令

I2C_ClearFlag(I2C1, I2C_FLAG_AF);

//printf("NACK!\n");

goto restart;

}

}

}

uint8_t read(uint8_t addr)

{

start();

I2C_SendData(I2C1, addr); // 发送存储器地址

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == ERROR);

I2C_GenerateSTART(I2C1, ENABLE); // RESTART

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT) == ERROR);

I2C_SendData(I2C1, 0xa1); // 从机地址(接收模式)

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED) == ERROR);

I2C_GenerateSTOP(I2C1,ENABLE); // 接收最后一字节数据前先准备好STOP信号

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED) == ERROR); // 等待数据接收完毕

while (I2C_GetFlagStatus(I2C1, I2C_FLAG_BUSY) == SET); // 等待停止信号发送完毕

return I2C_ReceiveData(I2C1);

}

void write(uint8_t addr, uint8_t value)

{

start();

I2C_SendData(I2C1, addr); // 前两个数据可连发, 无需等待TXE置位

I2C_SendData(I2C1, value);

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == ERROR); // 等待数据完全发送完毕

I2C_GenerateSTOP(I2C1,ENABLE);

while (I2C_GetFlagStatus(I2C1, I2C_FLAG_BUSY) == SET); // 等待停止信号发送完毕

}

void read_more(uint8_t addr, char *data, uint8_t len)

{

start();

I2C_SendData(I2C1, addr);

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == ERROR);

I2C_GenerateSTART(I2C1, ENABLE);

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT) == ERROR);

I2C_SendData(I2C1, 0xa1);

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED) == ERROR);

I2C_AcknowledgeConfig(I2C1, ENABLE);

while (len--)

{

if (len == 0)

{

I2C_AcknowledgeConfig(I2C1, DISABLE);

I2C_GenerateSTOP(I2C1,ENABLE); // 接收最后一字节数据前先准备好STOP信号

}

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED) == ERROR); // 等待当前数据接收完毕

*data++ = I2C_ReceiveData(I2C1);

}

while (I2C_GetFlagStatus(I2C1, I2C_FLAG_BUSY) == SET); // 等待停止信号发送完毕

}

void write_more(uint8_t addr, const char *data, uint8_t len) 

{

start();

I2C_SendData(I2C1, addr);

while (len--)

{

I2C_SendData(I2C1, *data++);

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTING) == ERROR); // 等待TXE

}

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == ERROR); // 等待全部数据发送完毕

I2C_GenerateSTOP(I2C1,ENABLE);

while (I2C_GetFlagStatus(I2C1, I2C_FLAG_BUSY) == SET); // 等待停止信号发送完毕

}

int main(void)

{

char str[20];

GPIO_InitTypeDef gpio;

I2C_InitTypeDef i2c;

USART_InitTypeDef usart;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB | RCC_APB2Periph_USART1, ENABLE);

// 串口发送引脚设为复用推挽输出

gpio.GPIO_Mode = GPIO_Mode_AF_PP;

gpio.GPIO_Pin = GPIO_Pin_9;

gpio.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(GPIOA, &gpio);

// I2C引脚设为复用开漏输出

gpio.GPIO_Mode = GPIO_Mode_AF_OD;

gpio.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;

GPIO_Init(GPIOB, &gpio);

USART_StructInit(&usart);

usart.USART_BaudRate = 115200;

usart.USART_Mode = USART_Mode_Tx;

USART_Init(USART1, &usart);

USART_Cmd(USART1, ENABLE);

I2C_StructInit(&i2c);

i2c.I2C_ClockSpeed = 100000;

I2C_Init(I2C1, &i2c);

I2C_Cmd(I2C1, ENABLE);

write(17, 0x31);

printf("read: 0x%02x\n", read(17));

write_more(17, "Hello!", 7); // 区域16~23

read_more(17, str, sizeof(str));

printf("str: %s\n", str);

write_more(8, "12345678ABCDEFG", 16); // 先将前8个字符写入地址8~15处, 然后回到地址8处写入剩下的字符, 包括最后的\0

read_more(8, str, sizeof(str));

printf("str: %s\n", str);

printf("I2C1->SR1=0x%04x, I2C1->SR2=0x%04x\n", I2C_ReadRegister(I2C1, I2C_Register_SR1), I2C_ReadRegister(I2C1, I2C_Register_SR2));

while (1)

__WFI();

}

【程序运行结果1】

read: 0x31

str: Hello!

str: ABCDEFG

I2C1->SR1=0x0000, I2C1->SR2=0x0000

两个SR寄存器的值都为0表明I2C正常工作。

【程序2：DMA方式】

#include

#include

DMA_InitTypeDef dma;

#define WRITE

#ifdef WRITE

const char eep_data[] = "The SDIO does not have an SPI-compatible communication mode. The SD memory card protocol is a superset of the MultiMediaCard protocol as defined in the MultiMediaCard system specification V2.11. Several commands required for SD memory devices are not supported by either SD I/O-only cards or the I/O portion of combo cards.";

#endif

int fputc(int ch, FILE *fp)

{

if (fp == stdout)

{

if (ch == '\n')

{

while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);

USART_SendData(USART1, '\r');

}

while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);

USART_SendData(USART1, ch);

}

return ch;

}

// 发送开始信号和从机地址(传输模式)

void start(void)

{

if (I2C1->SR1 || I2C1->SR2)

printf("error!\n");

restart:

I2C_GenerateSTART(I2C1, ENABLE);

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT) == ERROR); // 等待开始信号发送完毕

I2C_SendData(I2C1, 0xa0); // 从机地址(传输模式)

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED) == ERROR) // 等待从机确认

{

if (I2C_GetFlagStatus(I2C1, I2C_FLAG_AF) == SET)

{

// 若从机未响应, 则重试

// 执行了写操作后需要等待一段时间才能执行其他命令

I2C_ClearFlag(I2C1, I2C_FLAG_AF);

//printf("NACK!\n");

goto restart;

}

}

}

void read(uint8_t addr, char *data, uint16_t len)

{

dma.DMA_BufferSize = len;

dma.DMA_DIR = DMA_DIR_PeripheralSRC;

dma.DMA_MemoryBaseAddr = (uint32_t)data;

DMA_Init(DMA1_Channel7, &dma);

DMA_Cmd(DMA1_Channel7, ENABLE);

start();

I2C_SendData(I2C1, addr);

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == ERROR);

I2C_GenerateSTART(I2C1, ENABLE);

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT) == ERROR);

I2C_SendData(I2C1, 0xa1);

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED) == ERROR);

I2C_DMACmd(I2C1, ENABLE);

I2C_DMALastTransferCmd(I2C1, ENABLE);

I2C_AcknowledgeConfig(I2C1, ENABLE);

while (DMA_GetFlagStatus(DMA1_FLAG_TC7) == RESET);

DMA_ClearFlag(DMA1_FLAG_TC7);

DMA_Cmd(DMA1_Channel7, DISABLE);

I2C_GenerateSTOP(I2C1, ENABLE);

I2C_DMACmd(I2C1, DISABLE);

I2C_DMALastTransferCmd(I2C1, DISABLE);

I2C_AcknowledgeConfig(I2C1, DISABLE);

while (I2C_GetFlagStatus(I2C1, I2C_FLAG_BUSY) == SET);

}

void write(uint8_t addr, const char *data, uint8_t len) 

{

dma.DMA_BufferSize = len;

dma.DMA_DIR = DMA_DIR_PeripheralDST;

dma.DMA_MemoryBaseAddr = (uint32_t)data;

DMA_Init(DMA1_Channel6, &dma);

DMA_Cmd(DMA1_Channel6, ENABLE);

start();

I2C_SendData(I2C1, addr);

I2C_DMACmd(I2C1, ENABLE);

while (DMA_GetFlagStatus(DMA1_FLAG_TC6) == RESET);

DMA_ClearFlag(DMA1_FLAG_TC6);

DMA_Cmd(DMA1_Channel6, DISABLE);

while (I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == ERROR); // 等待全部数据发送完毕

I2C_GenerateSTOP(I2C1, ENABLE);

I2C_DMACmd(I2C1, DISABLE);

while (I2C_GetFlagStatus(I2C1, I2C_FLAG_BUSY) == SET);

}

#ifdef WRITE

void write_all(void)

{

uint16_t i;

for (i = 0; i < 256; i += 8)

write(i, eep_data + i, 8);

}

#endif

int main(void)

{

char str[257];

GPIO_InitTypeDef gpio;

I2C_InitTypeDef i2c;

USART_InitTypeDef usart;

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB | RCC_APB2Periph_USART1, ENABLE);

// 串口发送引脚设为复用推挽输出

gpio.GPIO_Mode = GPIO_Mode_AF_PP;

gpio.GPIO_Pin = GPIO_Pin_9;

gpio.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(GPIOA, &gpio);

USART_StructInit(&usart);

usart.USART_BaudRate = 115200;

usart.USART_Mode = USART_Mode_Tx;

USART_Init(USART1, &usart);

USART_Cmd(USART1, ENABLE);

// I2C引脚复位

gpio.GPIO_Mode = GPIO_Mode_IN_FLOATING;

gpio.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;

GPIO_Init(GPIOB, &gpio);

if (GPIO_ReadInputDataBit(GPIOB, GPIO_Pin_6) == Bit_RESET || GPIO_ReadInputDataBit(GPIOB, GPIO_Pin_7) == Bit_RESET)

{

printf("I2C reset!\n");

gpio.GPIO_Mode = GPIO_Mode_Out_OD;

GPIO_Init(GPIOB, &gpio);

GPIO_WriteBit(GPIOB, GPIO_Pin_6, Bit_SET);

GPIO_WriteBit(GPIOB, GPIO_Pin_7, Bit_SET);

}

// I2C引脚设为复用开漏输出

gpio.GPIO_Mode = GPIO_Mode_AF_OD;

GPIO_Init(GPIOB, &gpio);

I2C_StructInit(&i2c);

i2c.I2C_ClockSpeed = 100000;

I2C_Init(I2C1, &i2c);

I2C_Cmd(I2C1, ENABLE);

dma.DMA_M2M = DMA_M2M_Disable;

dma.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;

dma.DMA_MemoryInc = DMA_MemoryInc_Enable;

dma.DMA_Mode = DMA_Mode_Normal;

dma.DMA_PeripheralBaseAddr = (uint32_t)&I2C1->DR;

dma.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;

dma.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

dma.DMA_Priority = DMA_Priority_High;

#ifdef WRITE

write_all();

#endif

read(0, str, 256);

str[256] = '\0';

printf("%s\n", str);

printf("I2C1->SR1=0x%04x, I2C1->SR2=0x%04x\n", I2C_ReadRegister(I2C1, I2C_Register_SR1), I2C_ReadRegister(I2C1, I2C_Register_SR2));

while (1)

__WFI();

}

【程序运行结果2】

The SDIO does not have an SPI-compatible communication mode. The SD memory card protocol is a superset of the MultiMediaCard protocol as defined in the MultiMediaCard system specification V2.11. Several commands required for SD memory devices are not suppo

I2C1->SR1=0x0000, I2C1->SR2=0x0000