/*
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* dht11.c
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*
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* Created on: Aug 8, 2021
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* Author: Think
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*/
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#include "tim.h"
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#include "gpio.h"
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#include "main.h"
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typedef struct w1_gpio_s
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{
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GPIO_TypeDef *group;
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uint16_t pin;
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} w1_gpio_t;
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static w1_gpio_t W1Dat = /* IO pin connected to PA5 */
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{
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.group = GPIOA,
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.pin = GPIO_PIN_5,
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};
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#define W1DQ_Input() \
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{ \
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GPIO_InitTypeDef GPIO_InitStruct = {0}; \
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GPIO_InitStruct.Pin = W1Dat.pin; \
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GPIO_InitStruct.Mode = GPIO_MODE_INPUT; \
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GPIO_InitStruct.Pull = GPIO_PULLUP; \
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GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH; \
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HAL_GPIO_Init(W1Dat.group, &GPIO_InitStruct); \
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}
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#define W1DQ_Output() \
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{ \
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GPIO_InitTypeDef GPIO_InitStruct = {0}; \
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GPIO_InitStruct.Pin = W1Dat.pin; \
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GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP; \
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GPIO_InitStruct.Pull = GPIO_NOPULL; \
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GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH; \
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HAL_GPIO_Init(W1Dat.group, &GPIO_InitStruct); \
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}
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#define W1DQ_Write(x) HAL_GPIO_WritePin(W1Dat.group, W1Dat.pin, \
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(x==1)?GPIO_PIN_SET:GPIO_PIN_RESET)
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#define W1DQ_Read() HAL_GPIO_ReadPin(W1Dat.group, W1Dat.pin)
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/* 主机发送起始信号 */
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static void DHT11_StartSignal(void)
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{
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W1DQ_Output();
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/* 主机拉低 >= 18ms */
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W1DQ_Write(0);
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HAL_Delay(20);
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/* 主机拉高 >= 20~40us */
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W1DQ_Write(1);
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delay_us(30);
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W1DQ_Input();
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}
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uint8_t DHT11_RespondSignal(void)
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{
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uint8_t retry = 0;
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/* 总线变为低电平说明从设备发送了响应信号: 80us */
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while( W1DQ_Read() && retry <100)
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{
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retry++;
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delay_us(1);
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}
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/* 超时没有收到响应信号 */
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if(retry >= 100)
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return 1;
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/* 从设备再把总线拉高表示从设备要发送数据了: 80us */
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retry = 0;
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while( !W1DQ_Read() && retry <100)
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{
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retry++;
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delay_us(1);
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}
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/* 超时没有收到数据开始信号 */
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if(retry >= 100)
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return 1;
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return 0;
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}
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uint8_t DHT11_ReadBit(void) //读取一个位
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{
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uint8_t retry = 0;
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/* 从设备回复的每个位数据以低电平标置开始: 50us */
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while( W1DQ_Read() && retry<100 )
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{
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retry++;
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delay_us(1);
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}
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/* 数据位都用高电平表示, 但高电平的长短决定了数据是 1 or 0 */
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retry = 0;
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while( !W1DQ_Read() && retry<100 )
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{
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retry++;
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delay_us(1);
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}
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/* 判断数据位是 1(70us) or 0(26~28us)*/
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delay_us(40);
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if( W1DQ_Read() )
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return 1;
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else
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return 0;
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}
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uint8_t DHT11_ReadByte(void) //读取一个字节返回值位采集值
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{
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uint8_t i,dat;
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dat = 0;
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for(i=0; i<8; i++)
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{
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dat <<= 1;
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dat |= DHT11_ReadBit(); //每读取到一个位放到最后一位
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}
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return dat;
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}
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int DHT11_SampleData(float *temperature, float *humidity)
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{
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uint8_t humi_H8bit;
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uint8_t humi_L8bit;
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uint8_t temp_H8bit;
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uint8_t temp_L8bit;
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uint8_t check_sum;
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if( !temperature || !humidity )
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return -1;
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/* 主机发起起始信号并等到从设备的响应信号 */
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DHT11_StartSignal();
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if( 0 != DHT11_RespondSignal() )
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return -2;
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humi_H8bit = DHT11_ReadByte();
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humi_L8bit = DHT11_ReadByte();
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temp_H8bit = DHT11_ReadByte();
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temp_L8bit = DHT11_ReadByte();
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check_sum = DHT11_ReadByte();
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if( (humi_H8bit+humi_L8bit+temp_H8bit+temp_L8bit) != check_sum )
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return -3;
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*humidity = (humi_H8bit*100 + humi_L8bit) / 100.00;
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*temperature = (temp_H8bit*100 + temp_L8bit) / 100.00;
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return 0;
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}
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