经过一个星期的努力，终于让STM32的硬件I2C跑起来了

_____503___ · 发表于 2015-1-20 11:36:34

下面是我用寄存器写的读写GT9系列IC的代码。在读数据上还不能连续读取，只能一个地址一个数据的读，请各位大哥指正。

//////////////////////////////////////////////////////i2c_hard.c

#include "i2c_hard.h"

void I2C_Init(void)
{
////////////////I2C GPIO重映像
RCC->APB2ENR |= 1<<0; //使能AFIO时钟
AFIO->MAPR |= 1<<1; //控制I2C1的SCL和SDA复用功能在GPIO端口的映像 SCL/PB8，SDA/PB9

////////////////I2C GPIO配置
RCC->APB2ENR |= 1<<3;      //使能PORTB时钟

GPIOB->CRH &= 0xFFFFFF00;   //I2C1：PB8->SCL, PB9->SDL
GPIOB->CRH |= 0x000000FF;   //复用开漏输出

//GPIOB->CRL &= 0x00FFFFFF;   //I2C1：PB6->SCL, PB7->SDL
//GPIOB->CRL |= 0xFF000000;   //复用开漏输出

////////////////I2C 寄存器配置
RCC->APB1ENR |= 1<<21; //使能外设I2C1时钟

RCC->APB1RSTR |= 1<<21;   //复位I2C1
RCC->APB1RSTR &= ~(1<<21);  //复位结束I2C1

I2C1->CR2 |= 36;                //000010：2MHz ... 100100：36MHz，其他禁用(此处为36MHZ)

I2C1->CCR |= 0<<15; //I2C主模式 0：标准模式的I2C 1：快速模式的I2C
I2C1->CCR |= 90<<0; //时钟控制分频系数 = PCLK1/2/f（f为想得到的频率，此处PCLK1=36MHZ，f=200KHZ）

I2C1->TRISE |= 37; //最大允许SCL上升时间为1000ns，故TRISE[5:0]中必须写入(1000ns/(1000/36)ns = 36+1)

I2C1->CR1 |= 1<<10; //打开ACK应答,在接收到一个字节后返回一个应答
I2C1->CR1 |= 1<<6; //广播呼叫使能

I2C1->OAR1 |= 0<<15; //寻址模式 1 响应10位地址 0 响应7位地址
I2C1->OAR1 |= 1<<14; //必须始终由软件保持为 1
I2C1->OAR1 |= INTERFACE_ADDR<<1;//设置接口地址的 7~1位（接口地址设为0X30）

I2C1->CR2 |= 1<<9; //事件中断使能
I2C1->CR2 |= 1<<8; //出错中断使能

I2C1->CR1 |= 1<<0; //开启I2C1
}

void I2C_Start(void)     //I2C1产生起始条件
{
    I2C1->CR1 |= 1<<8;
}

void I2C_Stop(void)     //I2C1产生停止条件
{
    I2C1->CR1 |= 1<<9;
}

void I2C_End(void) //关闭I2C
{
I2C1->CR1 &= ~(1<<0);
}

void I2C_Write_U8(u8 data) //I2C1写一个字节
{
I2C1->DR = data;
}

u8 I2C_Read_U8(void) //I2C1读一个字节
{
while(!RXNE_STATUS); //接收到数据标志位

return I2C1->DR;
}

u8 I2C_Write(u16 addr, u8* data, u16 length)
{
u16 clear = 0;
u8 addr_l=0, addr_h=0;
u16 send_loop;

addr_h = (u8)(addr>>8);
addr_l = (u8)(addr&0x00FF);

I2C_Start();

while(!SB_STATUS);
I2C_Write_U8(WRITE_ADDR);

while(!ADDR_STATUS);
clear = I2C1->SR1;
clear = I2C1->SR2;
I2C_Write_U8(addr_h);

while(!BTF_STATUS);
I2C_Write_U8(addr_l);

for(send_loop=0;send_loop<length;send_loop++)
{
  while(!BTF_STATUS);
  I2C_Write_U8(*data);
  data++;
}

I2C_Stop();

return 0;
}

u8* I2C_Read(u16 addr, u8* data, u16 length)
{
u16 clear = 0;

u8 addr_l=0, addr_h=0;
u16 send_loop;

for(send_loop=0;send_loop<length;send_loop++)
{
  addr_h = (u8)(addr>>8);
  addr_l = (u8)(addr&0x00FF);

  I2C_Start();

  while(!SB_STATUS);
  I2C_Write_U8(WRITE_ADDR);

  while(!ADDR_STATUS);
  clear = I2C1->SR2;
  I2C_Write_U8(addr_h);

  while(!BTF_STATUS);
  I2C_Write_U8(addr_l);

  I2C_Start();

  while(!SB_STATUS);
  I2C_Write_U8(READ_ADDR);

  while(!ADDR_STATUS);
  clear = I2C1->SR2;

while(!BTF_STATUS);
clear = I2C1->SR1;

  *data = I2C_Read_U8();
  data++;

  addr++;

I2C_Stop();
}

return data;
}

//////////////////////////////////////////////////////i2c_hard.h

#ifndef __I2C_HARD_H
#define __I2C_HARD_H

#include "sys.h"
#include "led.h"
#include "delay.h"

#define WRITE_ADDR 0x28            //从设备（GT9）写数据地址
#define READ_ADDR 0x29         //从设备（GT9）读数据地址
#define INTERFACE_ADDR 0x30        //自身地址

#define SB_STATUS (I2C1->SR1 & 1<<0) //起始位（主模式）
#define ADDR_STATUS (I2C1->SR1 & 1<<1)//地址已被发送（主模式）
#define BTF_STATUS (I2C1->SR1 & 1<<2)//字节发送结束
#define RXNE_STATUS (I2C1->SR1 & 1<<6)//数据寄存器非空（接收时）

void I2C_Init(void);

void I2C_Start(void);
void I2C_Stop(void);
void I2C_End(void);
void I2C_Write_U8(u8 data);
u8 I2C_Read_U8(void);

u8 I2C_Write(u16 addr, u8* data, u16 length);
u8* I2C_Read(u16 addr, u8* data, u16 length);

#endif