一、引脚
二、代码
iic.c文件
#include "iic.h"
/* 初始化模拟IIC
*
*/
void IIC_Init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE); //使能GPIOA时钟
//GPIOB1,B2初始化设置
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1 | GPIO_Pin_2;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT; //普通输出模式
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; //推挽输出
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //100MHz
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; //上拉
GPIO_Init(GPIOB, &GPIO_InitStructure); //初始化
SCL_H;
SDA_H;
}
//产生IIC起始信号
void IIC_Start(void)
{
SDA_OUT(); //sda线输出
SDA_H;
SCL_H;
IIC_Delay_us(4);
SDA_L; //START:when CLK is high,DATA change form high to low
IIC_Delay_us(4);
SCL_L; //钳住I2C总线，准备发送或接收数据
}
//产生IIC停止信号
void IIC_Stop(void)
{
SDA_OUT(); //sda线输出
SCL_L;
SDA_L; //STOP:when CLK is high DATA change form low to high
IIC_Delay_us(2);
SCL_H;
IIC_Delay_us(1);
SDA_H; //发送I2C总线结束信号
IIC_Delay_us(4);
}
//等待应答信号到来
//返回值：1，接收应答失败
// 0，接收应答成功
u8 IIC_Wait_Ack(void)
{
u8 ucErrTime = 0;
SDA_IN(); //SDA设置为输入
SDA_H;
IIC_Delay_us(1);
SCL_H;
IIC_Delay_us(1);
while (SDA_READ)
{
ucErrTime++;
if (ucErrTime > 250)
{
IIC_Stop();
return 1;
}
}
SCL_L;
IIC_Delay_us(30);
return 0;
}
//产生ACK应答
void IIC_Ack(void)
{
SCL_L;
SDA_OUT();
SDA_L;
IIC_Delay_us(2);
SCL_H;
IIC_Delay_us(2);
SCL_L;
}
//不产生ACK应答
void IIC_NAck(void)
{
SCL_L;
SDA_OUT();
SDA_H;
IIC_Delay_us(2);
SCL_H;
IIC_Delay_us(2);
SCL_L;
}
//IIC发送一个字节
//返回从机有无应答
//1，有应答
//0，无应答
void IIC_Send_Byte(u8 txd)
{
u8 t;
SDA_OUT();
SCL_L; //拉低时钟开始数据传输
for (t = 0; t < 8; t++)
{
if (txd & 0x80)
SDA_H
else
SDA_L;
txd <<= 1;
IIC_Delay_us(2); //对TEA5767这三个延时都是必须的
SCL_H;
IIC_Delay_us(2);
SCL_L;
//IIC_Delay_us(2);
}
}
//读1个字节，ack=1时，发送ACK，ack=0，发送nACK
u8 IIC_Read_Byte(unsigned char ack)
{
unsigned char i, receive = 0;
SDA_IN(); //SDA设置为输入
for (i = 0; i < 8; i++)
{
SCL_L;
IIC_Delay_us(2);
SCL_H;
receive <<= 1;
if (SDA_READ)
receive++;
IIC_Delay_us(1);
}
if (!ack)
IIC_NAck(); //发送nACK
else
IIC_Ack(); //发送ACK
return receive;
}
//IIC延时函数
void IIC_Delay_us(u16 us)
{
{
u16 i = 0;
while (us--)
{
i = 6;
while (i--)
;
}
}
}
iic.h文件
#ifndef __IIC_H
#define __IIC_H
#include "stm32f4xx_conf.h"
/*
IIC_SCL --PB2
IIC_SDA --PB1
*/
//IO方向设置
#define SDA_IN() {GPIOB->MODER&=~(3<<(1*2));GPIOB->MODER|=0<<1*2;} //PB1输入模式
#define SDA_OUT() {GPIOB->MODER&=~(3<<(1*2));GPIOB->MODER|=1<<1*2;} //PB1输出模式
//IO操作函数
#define SCL_L {GPIOB->ODR&=0xFFFB;} //SCL拉低(1011)B
#define SCL_H {GPIOB->ODR|=0x0004;} //SCL拉高(0100)4
#define SDA_L {GPIOB->ODR&=0xFFFD;} //SDA拉低(1101)D
#define SDA_H {GPIOB->ODR|=0x0002;} //SDA拉高(0010)2
#define SDA_READ (GPIOB->IDR&0x0002) //SDA读取
#define ACK 1
#define NACK 0
void IIC_Init(void); //初始化IIC的IO口
void IIC_Start(void); //发送IIC开始信号
void IIC_Stop(void); //发送IIC停止信号
void IIC_Send_Byte(u8 byte); //IIC发送一个字节
u8 IIC_Read_Byte(unsigned char ack);//IIC读取一个字节
u8 IIC_Wait_Ack(void); //IIC等待ACK信号
void IIC_Ack(void); //IIC发送ACK信号
void IIC_NAck(void); //IIC不发送ACK信号
void IIC_Delay_us(u16 us); //IIC delay
#endif
htu21d.c
/**
******************************************************************************
* @file htu21d.c
* @brief HTU21D 温湿度模块驱动
******************************************************************************
*/
#include <stdio.h>
#include "htu21d.h"
#include "iic.h"
#include "delay.h"
#include "usart.h"
SENSOR_DATA_t g_sensorData ={0,0,0,0,0};
static u32 timer = 0;
static u8 isTempOrHumi = 1;//Temp firth,humi second;
static u8 htu21_res=0;
/*
* HTU21D模块初始化函数
*/
void HTU21D_Init(void){
IIC_Start();
IIC_Send_Byte(HTU21D_IIC_ADDR<<1);
IIC_Wait_Ack();
IIC_Send_Byte(CMD_RESET_CH21D);
IIC_Wait_Ack();
IIC_Stop();
Delay_ms(18);
HTU21D_Temp_Trig();
Delay_ms(60);
}
/*
*
*/
u8 HTU21D_ReadSensor(void){
if(HasElapsed(&timer, 500)){
if(isTempOrHumi){
htu21_res = HTU21D_Read_Temp(&g_sensorData.innerTemp);
HTU21D_Humi_Trig();
isTempOrHumi = 0;
}else{
htu21_res = HTU21D_Read_Humi(&g_sensorData.humi);
HTU21D_Temp_Trig();
isTempOrHumi = 1;
}
}
return htu21_res;
}
/*
* 读取计算温度函数
*/
u8 HTU21D_Read_Temp(float* temp){
u32 data;
IIC_Start();
IIC_Send_Byte((HTU21D_IIC_ADDR<<1)+1);
if(!IIC_Wait_Ack()){
data = IIC_Read_Byte(ACK);
data <<= 8;
data += IIC_Read_Byte(ACK);
data <<= 8;
data += IIC_Read_Byte(NACK);
IIC_Stop();
data >>= 8;
data &= 0xFFFC;
*temp = (175.72*data)/65536 - 46.85;
return 0;
}
//iic error
return 1;
}
/*
* 读取计算湿度函数
*/
u8 HTU21D_Read_Humi(float* humi){
u32 data;
IIC_Start();
IIC_Send_Byte((HTU21D_IIC_ADDR<<1)+1);
if(!IIC_Wait_Ack()){
data = IIC_Read_Byte(ACK);
data <<= 8;
data += IIC_Read_Byte(ACK);
data <<= 8;
data += IIC_Read_Byte(NACK);
IIC_Stop();
data >>= 8;
data &= 0xFFF0;
*humi = (125.0*data)/65536 - 6;
return 0;
}
//iic error
return 1;
}
/*
* 开始温度检测函数
*/
void HTU21D_Temp_Trig(){
IIC_Start();
IIC_Send_Byte(HTU21D_IIC_ADDR<<1);
IIC_Wait_Ack();
IIC_Send_Byte(CMD_T_TRIG);
IIC_Wait_Ack();
}
/*
* 开始湿度检测函数
*/
void HTU21D_Humi_Trig(){
IIC_Start();
IIC_Send_Byte(HTU21D_IIC_ADDR<<1);
IIC_Wait_Ack();
IIC_Send_Byte(CMD_RH_TRIG);
IIC_Wait_Ack();
}
htu21d.h
#ifndef __HTU21D_H
#define __HTU21D_H
#include "stm32f4xx_conf.h"
typedef struct
{
float pressure;
float depth;
float innerTemp;
float humi;
float waterTemp;
}SENSOR_DATA_t;
extern SENSOR_DATA_t g_sensorData;
#define HTU21D_IIC_ADDR 0x40 // the HTU21D 7 bits iic device addr
#define CMD_LOADER_DATA 0x81 //the HTU21D iic device addr to read data
#define CMD_T_TRIG_HOSTMODEL 0xE3 //trigger of measure temperature command
#define CMD_RH_TRIG_HOSTMODEL 0xE5 //trigger of measure relative humidity command
#define CMD_T_TRIG 0xF3 //trigger of measure temperature command
#define CMD_RH_TRIG 0xF5 //trigger of measure relative humidity command
#define CMD_USER_WRITE 0xE6 //write user reg command
#define CMD_USER_READ 0xE7 //read user reg command
#define CMD_RESET_CH21D 0xFE //HTU21D reset command
void HTU21D_Init(void);
u8 HTU21D_ReadSensor(void);
u8 HTU21D_Read_Temp(float* temp);
u8 HTU21D_Read_Humi(float* humi);
void HTU21D_Temp_Trig(void);
void HTU21D_Humi_Trig(void);
void HTU21D_Process(void);
#endif
main.c
void HTU21D_Process(void)
{
HTU21D_ReadSensor() printf("temp:%.3f,humi:%.3f\r\n",g_sensorData.innerTemp,g_sensorData.humi);
}
}
int main()
{
while(1)
{
HTU21D_Process();
delay_ms(100);
}
}