软件模拟i2c的使用
软件模拟i2c的使用1、i2c硬件资源不太够的时候，可以用普通gpio模拟i2c的功能，话不多说，直接上代码，使用时直接替换对应管脚即可。2、代码如下：#include <stdio.h>
#include <stdint.h>
#include "main.h"
#include "type.h"
#include "SwI2c.h"
#include "n32g430.h"
#include "timer.h"
// PB8 scl PB9 sda
#define SWI2C1_SCL_PORT GPIOB
#define SWI2C1_SCL_PIN GPIO_PIN_8
#define SWI2C1_SCL_CLOCK RCC_AHB_PERIPH_GPIOB
#define SWI2C1_SCL_HIGH GPIO_Pins_Set(SWI2C1_SCL_PORT,SWI2C1_SCL_PIN)
#define SWI2C1_SCL_LOW GPIO_Pins_Reset(SWI2C1_SCL_PORT,SWI2C1_SCL_PIN)
#define SWI2C1_SDA_PORT GPIOB
#define SWI2C1_SDA_PIN GPIO_PIN_9
#define SWI2C1_SDA_CLOCK RCC_AHB_PERIPH_GPIOB
#define SWI2C1_SDA_HIGH GPIO_Pins_Set(SWI2C1_SDA_PORT,SWI2C1_SDA_PIN)
#define SWI2C1_SDA_LOW GPIO_Pins_Reset(SWI2C1_SDA_PORT,SWI2C1_SDA_PIN)
#define SWI2C1_SDA_READ GPIO_Input_Pin_Data_Get(SWI2C1_SDA_PORT,SWI2C1_SDA_PIN)
#define BIT0 0x01
#define BIT7 0x80
void SwI2c_Gpio_Init(void)
{
/* Define a structure of type GPIO_InitType */
GPIO_InitType GPIO_InitStructure;
/* Enable LED related GPIO peripheral clock */
RCC_AHB_Peripheral_Clock_Enable(SWI2C1_SCL_CLOCK);
RCC_AHB_Peripheral_Clock_Enable(SWI2C1_SDA_CLOCK);
/* Assign default value to GPIO_InitStructure structure */
GPIO_Structure_Initialize(&GPIO_InitStructure);
/* Select the GPIO pin to control */
GPIO_InitStructure.Pin = SWI2C1_SCL_PIN;
/* Set pin mode to general push-pull output */
GPIO_InitStructure.GPIO_Mode = GPIO_MODE_OUT_OD;
GPIO_InitStructure.GPIO_Pull = GPIO_PULL_UP;
/* Set the pin drive current to 4MA*/
GPIO_InitStructure.GPIO_Current = GPIO_DS_4MA;
GPIO_InitStructure.GPIO_Slew_Rate = GPIO_SLEW_RATE_FAST;
/* Initialize GPIO */
GPIO_Peripheral_Initialize(SWI2C1_SCL_PORT, &GPIO_InitStructure);
/* Select the GPIO pin to control */
GPIO_InitStructure.Pin = SWI2C1_SDA_PIN;
/* Set pin mode to general push-pull output */
GPIO_InitStructure.GPIO_Mode = GPIO_MODE_OUT_OD;
GPIO_InitStructure.GPIO_Pull = GPIO_PULL_UP;
/* Set the pin drive current to 4MA*/
GPIO_InitStructure.GPIO_Current = GPIO_DS_4MA;
GPIO_InitStructure.GPIO_Slew_Rate = GPIO_SLEW_RATE_FAST;
/* Initialize GPIO */
GPIO_Peripheral_Initialize(SWI2C1_SDA_PORT, &GPIO_InitStructure);
SWI2C1_SDA_HIGH;
SWI2C1_SCL_HIGH;
}
static void SwI2c_Delay_Us(int32_t us)
{
TIM3_Delay_Us(us);
}
static void SwI2c_Sda_Config_Output_mode(void)
{
GPIO_InitType GPIO_InitStructure;
/* Assign default value to GPIO_InitStructure structure */
GPIO_Structure_Initialize(&GPIO_InitStructure);
/* Select the GPIO pin to control */
GPIO_InitStructure.Pin = SWI2C1_SDA_PIN;
/* Set pin mode to general push-pull output */
GPIO_InitStructure.GPIO_Mode = GPIO_MODE_OUT_OD;
GPIO_InitStructure.GPIO_Pull = GPIO_PULL_UP;
/* Set the pin drive current to 4MA*/
GPIO_InitStructure.GPIO_Current = GPIO_DS_4MA;
GPIO_InitStructure.GPIO_Slew_Rate = GPIO_SLEW_RATE_FAST;
/* Initialize GPIO */
GPIO_Peripheral_Initialize(SWI2C1_SDA_PORT, &GPIO_InitStructure);
SWI2C1_SDA_HIGH;
}
static void SwI2c_Sda_Config_Input_mode(void)
{
GPIO_InitType GPIO_InitStructure;
/* Assign default value to GPIO_InitStructure structure */
GPIO_Structure_Initialize(&GPIO_InitStructure);
/* Select the GPIO pin to control */
GPIO_InitStructure.Pin = SWI2C1_SDA_PIN;
/* Set pin mode to general push-pull output */
GPIO_InitStructure.GPIO_Mode = GPIO_MODE_INPUT;
GPIO_InitStructure.GPIO_Pull = GPIO_PULL_UP;
/* Set the pin drive current to 4MA*/
GPIO_InitStructure.GPIO_Current = GPIO_DS_4MA;
GPIO_InitStructure.GPIO_Slew_Rate = GPIO_SLEW_RATE_FAST;
/* Initialize GPIO */
GPIO_Peripheral_Initialize(SWI2C1_SDA_PORT, &GPIO_InitStructure);
}
void SwI2c_Start(void)
{
SWI2C1_SCL_LOW; //先使SCL = 0, 为SDA上的电平改变做准备
SwI2c_Delay_Us(2);
SWI2C1_SDA_HIGH; //SDA = 1
SwI2c_Sda_Config_Output_mode(); //sda OD 初始化输出1,
SWI2C1_SDA_HIGH; //SDA = 1, 此时SDA的电平变化对通讯双方没有影响
SwI2c_Delay_Us(2);
SWI2C1_SCL_HIGH; //SCL = 1
SwI2c_Delay_Us(2);
SWI2C1_SDA_LOW; //SDA=0,产生下降沿,启动IIC通讯
SwI2c_Delay_Us(2);
SWI2C1_SCL_LOW; //SCL=0,为SDA上的电平改变做准备
SwI2c_Delay_Us(2);
}
void SwI2c_Stop(void) //停止信号
{
SWI2C1_SCL_LOW ; //先使SCL = 0, 为SDA上的电平改变做准备
SwI2c_Delay_Us(2);
SWI2C1_SDA_HIGH; //SDA = 1
SwI2c_Sda_Config_Output_mode(); //sda OD 初始化输出1,
SWI2C1_SDA_HIGH;
SwI2c_Delay_Us(2);
SWI2C1_SDA_LOW; //SDA=0,此时SDA的电平变化对通讯双方没有影响
SwI2c_Delay_Us(2);
SWI2C1_SCL_HIGH; //SCL=1
SwI2c_Delay_Us(2);
SWI2C1_SDA_HIGH; //SDA=1,结束IIC通讯
SwI2c_Delay_Us(2); //SDA在结束后维持在高电平,如果有干扰脉冲产生而使得SDA
//变低,则干扰过后会恢复高电平. 此时SCL如果因干扰而处于
return;
}
MI_U8 SwI2c_Wait_Ack(void) //等待应答信号：0-应答；1-非应答
{
MI_U8 uc_time = 0;
SwI2c_Sda_Config_Input_mode(); //SDA定义为输入
SWI2C1_SDA_HIGH;
SwI2c_Delay_Us(1);
SWI2C1_SCL_HIGH;
SwI2c_Delay_Us(1);
while (SWI2C1_SDA_READ)
{
uc_time++;
if (uc_time > 250)
{
SwI2c_Stop();
return 1;
}
}
SWI2C1_SCL_LOW;
return 0;
}
void SwI2c_Ack(void) //产生 ACK 应答
{
SWI2C1_SDA_HIGH; //SDA = 1
SwI2c_Sda_Config_Output_mode(); //sda OD 初始化输出1,
SWI2C1_SDA_HIGH; //SDA输出高电平
SWI2C1_SDA_LOW; //清SDA="0",CPU发低电平确认信号,
SwI2c_Delay_Us(2);
SWI2C1_SCL_HIGH; //置SCL="1", 产生上升沿,发送一位确认数据
SwI2c_Delay_Us(2);
SWI2C1_SCL_LOW; //清SCL="0",为SDA上的电平改变做准备
return;
}
void Swi2c_No_Ack(void) //产生 NACK 非应答
{
SWI2C1_SDA_HIGH; //SDA = 1
SwI2c_Sda_Config_Output_mode(); //sda OD 初始化输出1,
SWI2C1_SDA_HIGH; //置SDA=1, CPU发"高电平非应答确认"信号
SwI2c_Delay_Us(2);
SWI2C1_SCL_HIGH; //置SCL="1", 产生上升沿,发送一位确认数据
SwI2c_Delay_Us(2);
SWI2C1_SCL_LOW; //清SCL="0",为SDA上的电平改变做准备
return;
}
//IIC 发送一个字节
MI_BOOL SwI2c_Write_Byte(MI_U8 data)
{
MI_U8 m; //SDA = 1
SwI2c_Sda_Config_Output_mode(); //sda OD 初始化输出1,
for (m = 0; m < 8; m++)
{
SWI2C1_SCL_LOW; //SCL=0,为SDA上的电平改变做准备
SwI2c_Delay_Us(2);
if (data & BIT7) //由最高位开始发送
{
SWI2C1_SDA_HIGH;
}
else
{
SWI2C1_SDA_LOW;
}
SwI2c_Delay_Us(2);
SWI2C1_SCL_HIGH; //SCL="1",产生上升沿,发送一位数据
SwI2c_Delay_Us(2);
data <<= 1;
}
SWI2C1_SCL_LOW; //清SCL="0",产生下降沿, 器件使SDA="0"
SwI2c_Delay_Us(2);
SwI2c_Sda_Config_Input_mode(); //SDA改为输入,准备接收确认应答
SWI2C1_SCL_HIGH; //SCL="1",让CPU在此期间读取SDA上的信号
for (m = 0; m < 8; m++)
{
SwI2c_Delay_Us(2);
if (SWI2C1_SDA_READ == 0)
{
SWI2C1_SCL_LOW; //清SCL="0",为SDA上的电平改变做准备
SwI2c_Delay_Us(2);
return MI_TRUE; //收到正确的低电平应答
}
}
SWI2C1_SCL_LOW; //清SCL="0",为SDA上的电平改变做准备
return MI_FALSE;
}
//读一个字节
MI_U8 SwI2c_Read_Byte()
{
MI_U8 m, data;
SwI2c_Sda_Config_Input_mode(); //SDA改为输入,准备接收数据
data = 0;
for (m = 0; m < 8; m++)
{
SWI2C1_SCL_LOW; //SCL="0",产生下降沿, 器件串出一位数据
SwI2c_Delay_Us(2);
SWI2C1_SCL_HIGH; //置SCL="1", 让CPU在此期间读取SDA上的信号
SwI2c_Delay_Us(2);
data <<= 1;
if (SWI2C1_SDA_READ)
{
data |= BIT0;
}
else
{
data &= (~BIT0);
}
}
SWI2C1_SCL_LOW; //清SCL="0",为SDA上的电平改变做准备
return data;
}
MI_BOOL SwI2c_Device_Write_Data(MI_U8 device_addr,MI_U8 *reg_addr,
uint16_t reg_len,const MI_U8 *buf,MI_U8 len)
{
SwI2c_Start();
SwI2c_Write_Byte(device_addr);
while (reg_len != 0)
{
if (SwI2c_Write_Byte(*reg_addr++) == MI_FALSE) //发送一字节数据
{
SwI2c_Stop();
return MI_FALSE;
}
reg_len--;
}
while (len != 0)
{
if (SwI2c_Write_Byte( *buf++) == MI_FALSE) //发送一字节数据
{
SwI2c_Stop();
return MI_FALSE;
}
len--;
}
SwI2c_Stop();
return MI_TRUE;
}
MI_U8 SwI2c_Device_Read_Data(MI_U8 device_addr,MI_U8 *reg_addr,
uint16_t reg_len, MI_U8 *buf,MI_U8 len)
{
SwI2c_Start();
SwI2c_Write_Byte(device_addr);
while (reg_len != 0)
{
if (SwI2c_Write_Byte(*reg_addr++) == MI_FALSE) //发送一字节数据
{
SwI2c_Stop();
return MI_FALSE;
}
reg_len--;
}
SwI2c_Start();
SwI2c_Write_Byte(device_addr + 1);
while (1)
{
*buf++ = SwI2c_Read_Byte(); //接收一字节
len--;
if (0 == len)
{
break;
}
SwI2c_Ack(); //未读完,CPU发低电平确认应答信号,以便读取下8位数据
}
Swi2c_No_Ack(); //已读完所有的数据,CPU发"高电平非应答确认"信号
SwI2c_Stop();
return MI_TRUE;
}
.h文件#ifndef _SWI2C_H__
#define _SWI2C_H__
void SwI2c_Gpio_Init(void);
MI_U8 SwI2c_Device_Read_Data(MI_U8 device_addr,MI_U8 *reg_addr,
uint16_t reg_len,MI_U8 *buf,MI_U8 len);
MI_BOOL SwI2c_Device_Write_Data(MI_U8 device_addr,MI_U8 *reg_addr,
uint16_t reg_len,const MI_U8 *buf,MI_U8 len);
#endif//_SWI2C_H__
3、延时函数换成自己的即可，楼主为了准确性，延时函数开了一个定时器。
prescaler = 64-1 ,1us加一次，Period设置最大，最大延时数就是这个。
相应代码如下void TIM3_Init(void)
{
RCC_APB1_Peripheral_Clock_Enable(RCC_APB1_PERIPH_TIM3);
TIM_TimeBaseInitType TIM_TimeBaseStructure;
TIM_Base_Struct_Initialize(&TIM_TimeBaseStructure);
TIM_TimeBaseStructure.Period = 65535-1;
TIM_TimeBaseStructure.Prescaler = 64-1;
TIM_TimeBaseStructure.ClkDiv = 0;
TIM_TimeBaseStructure.CntMode = TIM_CNT_MODE_UP;
TIM_Base_Initialize(TIM3, &TIM_TimeBaseStructure);
TIM_Base_Reload_Mode_Set(TIM2, TIM_PSC_RELOAD_MODE_IMMEDIATE);
}
void TIM3_Delay_Us(__IO uint32_t us)
{
TIM_Base_Count_Set(TIM3,0);
TIM_On(TIM3);
while(TIM_Base_Count_Get(TIM3) < us);
TIM_Off(TIM3);
}
软件一致性很强
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