PIC16F887 DHT-11 LCD Example Using XC8

DHT11 converts the surrounding temperature and humidity to serial digital data for any micro-processor. It uses only one serial data wire. It able to convert between 0 and 50 degree Celsius in temperature, and 0 to 90RH for humidity. It's suitable for air conditioning system, agricultural application, etc.

DHT-11 Sensor

Prototyping Board

It contains 5 bytes (40 bits) of digital data. They are 1 byte of humidity, 1 byte of temperature, and 1 byte of check sum. For more information about decoding its data byte please check this post.

DTH-11 Sensor

 

TC1604A-01 16x4 Character LCD Module

In this example, I use an 8-bit PIC micro-controller PIC16F887, a DHT-11 sensor module, and a 16x2 character LCD to read and display the environmental data. I use the Microchip MPLABX IDE v6.15 and its XC8 C compiler v2.36 (free version).

/*
 * File:   main.c
 * Author: Admin
 *
 * Created on December 26, 2023, 9:03 PM
 * PIC16F887 DHT-11 Sensor and LCD Example
 * MPLABX IDE v6.15 XC8 v2.36
 */
 
#include <xc.h>
#include "config.h"
#include "LCD4Bits.h"
#include <stdio.h>
 
#define _XTAL_FREQ 8000000UL
 
#define DATA_PIN    RD0
#define DATA_DIR    TRISD0
 
uint8_t data[5];
void readDHT11(void){
    for(uint8_t i=0;i<5;i++) data[i]=0;  
    DATA_DIR=0;
    DATA_PIN=1;
    __delay_ms(10);
    DATA_PIN=0;
    __delay_ms(18);
    DATA_PIN=1;
    __delay_us(30);
    DATA_PIN=0;
    DATA_DIR=1;
    __delay_us(10);
    while(DATA_PIN==0);
    __delay_us(10);
    while(DATA_PIN==1);
    __delay_us(10);
 
    //Start of Transmission  
    for(uint8_t i=0;i<5;i++) {
        for(uint8_t j=0;j<8;j++){
        __delay_us(5);
        while(DATA_PIN==0);
        __delay_us(50);
        if(DATA_PIN==1) { data[i]|=(1<<7-j); while(DATA_PIN==1);}
    }
       __delay_us(10);
    }
    /*CRC Calculation - the last byte data[4] is check sum*/
    uint8_t crc = data[0]+data[1]+data[2]+data[3];
    if(crc!=data[4]) {for(uint8_t i=0;i<4;i++) data[i]=0; return;}
    __delay_us(10);
}
 
 
void main(void) {
    OSCCONbits.IRCF=7;
    char msg[8];
    PORTA=0;
    TRISA=0;
    lcdInit();
    lcdString("Temperature:");
    __delay_ms(1000);
    while(1){
        readDHT11();
        sprintf(msg,"%2dRH",data[0]);
        lcdXY(1,2); lcdString(msg);
        sprintf(msg,"%2d%cC",data[2],223);
        lcdXY(8,2); lcdString(msg);
        __delay_ms(500);
    }
    return;
}
 

I use its 8MHz internal oscillator clock source leaving the XTAL1 and XTAL2 pin opened.

Dashboard

Running Program

Running Program

 

Simulating Program

Proteus VSM can be used for circuit design and simulation. Click here to download its source file.