[PIC] Interfacing DHT11 to Pic using xc8 compiler

[Sarit]

Hey there, I've been trying to interface a DHT11 sensor to a pic18F4550 and coding with xC8 compiler. Actually I've modified it from a website. I've successfully loaded a hex file into the MCU but the LCD only displays zero humidity and zero temperature. I've checked and my circuit has no problem. The DHT11 sensor is also working, I guessed the problem may be with the software... Can someone point out where I'm missing it. Thanks.

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Code C - [expand]
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/* MCU Definitions */
#include <p18cxxx.h>
#include <string.h>
#include <plib/delays.h>
#include <stdio.h>
#include <plib/xlcd.h>
 
 
// PIC18F4550 Configuration Bit Settings
 
// 'C' source line config statements
 
#include <xc.h>
 
// #pragma config statements should precede project file includes.
// Use project enums instead of #define for ON and OFF.
 
// CONFIG1L
#pragma config PLLDIV = 5       // PLL Prescaler Selection bits (Divide by 5 (20 MHz oscillator input))
#pragma config CPUDIV = OSC1_PLL2// System Clock Postscaler Selection bits ([Primary Oscillator Src: /1][96 MHz PLL Src: /2])
#pragma config USBDIV = 2       // USB Clock Selection bit (used in Full-Speed USB mode only; UCFG:FSEN = 1) (USB clock source comes from the 96 MHz PLL divided by 2)
 
// CONFIG1H
#pragma config FOSC = INTOSCIO_EC// Oscillator Selection bits (Internal oscillator, port function on RA6, EC used by USB (INTIO))
#pragma config FCMEN = OFF      // Fail-Safe Clock Monitor Enable bit (Fail-Safe Clock Monitor disabled)
#pragma config IESO = OFF       // Internal/External Oscillator Switchover bit (Oscillator Switchover mode disabled)
 
// CONFIG2L
#pragma config PWRT = OFF       // Power-up Timer Enable bit (PWRT disabled)
#pragma config BOR = OFF        // Brown-out Reset Enable bits (Brown-out Reset disabled in hardware and software)
#pragma config BORV = 3         // Brown-out Reset Voltage bits (Minimum setting)
#pragma config VREGEN = OFF     // USB Voltage Regulator Enable bit (USB voltage regulator disabled)
 
// CONFIG2H
#pragma config WDT = OFF        // Watchdog Timer Enable bit (WDT disabled (control is placed on the SWDTEN bit))
#pragma config WDTPS = 32768    // Watchdog Timer Postscale Select bits (1:32768)
 
// CONFIG3H
#pragma config CCP2MX = ON      // CCP2 MUX bit (CCP2 input/output is multiplexed with RC1)
#pragma config PBADEN = OFF     // PORTB A/D Enable bit (PORTB<4:0> pins are configured as digital I/O on Reset)
#pragma config LPT1OSC = OFF    // Low-Power Timer 1 Oscillator Enable bit (Timer1 configured for higher power operation)
#pragma config MCLRE = OFF      // MCLR Pin Enable bit (RE3 input pin enabled; MCLR pin disabled)
 
// CONFIG4L
#pragma config STVREN = ON      // Stack Full/Underflow Reset Enable bit (Stack full/underflow will cause Reset)
#pragma config LVP = OFF        // Single-Supply ICSP Enable bit (Single-Supply ICSP disabled)
#pragma config ICPRT = OFF      // Dedicated In-Circuit Debug/Programming Port (ICPORT) Enable bit (ICPORT disabled)
#pragma config XINST = OFF      // Extended Instruction Set Enable bit (Instruction set extension and Indexed Addressing mode disabled (Legacy mode))
 
// CONFIG5L
#pragma config CP0 = OFF        // Code Protection bit (Block 0 (000800-001FFFh) is not code-protected)
#pragma config CP1 = OFF        // Code Protection bit (Block 1 (002000-003FFFh) is not code-protected)
#pragma config CP2 = OFF        // Code Protection bit (Block 2 (004000-005FFFh) is not code-protected)
#pragma config CP3 = OFF        // Code Protection bit (Block 3 (006000-007FFFh) is not code-protected)
 
// CONFIG5H
#pragma config CPB = OFF        // Boot Block Code Protection bit (Boot block (000000-0007FFh) is not code-protected)
#pragma config CPD = OFF        // Data EEPROM Code Protection bit (Data EEPROM is not code-protected)
 
// CONFIG6L
#pragma config WRT0 = OFF       // Write Protection bit (Block 0 (000800-001FFFh) is not write-protected)
#pragma config WRT1 = OFF       // Write Protection bit (Block 1 (002000-003FFFh) is not write-protected)
#pragma config WRT2 = OFF       // Write Protection bit (Block 2 (004000-005FFFh) is not write-protected)
#pragma config WRT3 = OFF       // Write Protection bit (Block 3 (006000-007FFFh) is not write-protected)
 
// CONFIG6H
#pragma config WRTC = OFF       // Configuration Register Write Protection bit (Configuration registers (300000-3000FFh) are not write-protected)
#pragma config WRTB = OFF       // Boot Block Write Protection bit (Boot block (000000-0007FFh) is not write-protected)
#pragma config WRTD = OFF       // Data EEPROM Write Protection bit (Data EEPROM is not write-protected)
 
// CONFIG7L
#pragma config EBTR0 = OFF      // Table Read Protection bit (Block 0 (000800-001FFFh) is not protected from table reads executed in other blocks)
#pragma config EBTR1 = OFF      // Table Read Protection bit (Block 1 (002000-003FFFh) is not protected from table reads executed in other blocks)
#pragma config EBTR2 = OFF      // Table Read Protection bit (Block 2 (004000-005FFFh) is not protected from table reads executed in other blocks)
#pragma config EBTR3 = OFF      // Table Read Protection bit (Block 3 (006000-007FFFh) is not protected from table reads executed in other blocks)
 
// CONFIG7H
#pragma config EBTRB = OFF      // Boot Block Table Read Protection bit (Boot block (000000-0007FFh) is not protected from table reads executed in other blocks)
 
 
 
 
#define _XTAL_FREQ 4000000    //Chip FREQUENCY
/* DHT11 I/O Macros  */
#ifndef DHT11
#define DHT11_TRIS  TRISDbits.TRISD1
#define DHT11_PIN  PORTDbits.RD1
#endif
 
/* Globals   */
char dht_dat[10]; // Output data will be here
unsigned char GlobalErr = 0;
unsigned char Buffer[20];
unsigned char Buffer1[20];
unsigned char t[20];
unsigned char n[20];
 
/* Function Prototypes */
void dht_init(void);
unsigned char dht_poll(void);
void read_dht(void);
 
//a simple delay function
void Wait(unsigned int delay)//delay for 100ms
{
    for(;delay;delay--)
        __delay_us(100);
}
/* Functions           */
void dht_init() {
    Delay1KTCYx(5); // 1ms
    DHT11_TRIS = 0;
    DHT11_PIN = 1;
}
 
unsigned char dht_poll() {
    unsigned char i = 0;
    unsigned char result = 0;
 
    DHT11_TRIS = 1;
    for (i = 0; i < 8; i++) {
        while (DHT11_PIN == 0);
        Delay10TCYx(15); //30us
        if (DHT11_PIN == 1) {
            result |= (1 << (7 - i));
        }
        while (DHT11_PIN == 1);
    }
    return result;
}
 
void read_dht() {
    unsigned char dht_in;
    unsigned char i;
    GlobalErr = 0;
    dht_init();
    DHT11_PIN = 0;  //port value is low
    Delay1KTCYx(90); // 18ms
    DHT11_PIN = 1;  //port value is high
    Delay100TCYx(1); // 20-40us
    DHT11_TRIS = 1; //make pin input
    dht_in = DHT11_PIN;
    if (dht_in) {
        GlobalErr = 1;
        return;
    }
    Delay100TCYx(4); // 80us
    dht_in = DHT11_PIN;
    if (!dht_in) {
        GlobalErr = 2;
        return;
    }
    Delay100TCYx(4); // 80us
    for (i = 0; i < 5; i++) {
        dht_dat[i] = dht_poll();
    }
    DHT11_PIN = 1;
    DHT11_TRIS = 0;
}
/* _user_putc()
 * Check for more information :
 * C18 Standart Libraries "Output Streams"
 */
int _user_putc(char c) {
    putcXLCD(c);
}
//Function to Initialise the LCD module
void init_XLCD(void)                //Initialize LCD display
{
    OpenXLCD(FOUR_BIT & LINES_5X7);  //configure LCD in 4-bit Data Interface mode
                                     //and 5x7 characters, multiple line display
    while(BusyXLCD());             //Check if the LCD controller is not busy
                                     //before writing some commands?
    WriteCmdXLCD(0x06);            // move cursor right, don?t shift display
    WriteCmdXLCD(0x0C);            //turn display on without cursor
 
 }
 
/*  Main Application         */
void main(void) {
    unsigned char dht11_crc = 0;
 
    ADCON1 |= 0x0F; // ADC All Digital
    CMCON = 0x07; // Comparators off
    //Let the LCD Module start up
   Wait(1);
   //Initialize the LCD Module
   init_XLCD();
   Wait(8); // Some Delay
 
    dht_init(); // DHT11 PreInit
    /*Main Loop*/
    while (1) {
        memset(dht_dat, 0x0, sizeof (dht_dat));
        read_dht(); // Check dht_dat variable after this funciton
        dht11_crc = dht_dat[0] + dht_dat[1] + dht_dat[2] + dht_dat[3]; // check check_sum
 
        if (dht_dat[4] != dht11_crc || GlobalErr>0) {
            sprintf(t,"CRC ERR :%02x!%02X   ", dht_dat[4], dht11_crc);
            sprintf(n,"Resp. Err:%d   ", GlobalErr);
 
            putrsXLCD(t);         //Display humidity on the screen
            while(BusyXLCD());
            WriteCmdXLCD(0xC0);
            while(BusyXLCD());
            putsXLCD(n);           //Display the Temperature on the screen
 
        } else {
            sprintf(Buffer,"HUMI RH :%d.%d %%  ", dht_dat[0], dht_dat[1]);
             sprintf(Buffer1,"TEMP    :%d.%d %cC  ", dht_dat[2], dht_dat[3], 223);
 
            putrsXLCD(Buffer);         //Display "Voltage" on the screen
            while(BusyXLCD());
            WriteCmdXLCD(0xC0);
            while(BusyXLCD());
            putsXLCD(Buffer1);              //Display the Temperature on the screen
            putrsXLCD("   ");           // Clear after comma
            WriteCmdXLCD(0x02);
        }
        }
        Delay10KTCYx(250);
        Delay10KTCYx(250); // Min. 1sn
        //Delay10KTCYx(250);
        //Delay10KTCYx(250); // 2sn Ideal Delay
    } /* Main Loop Ends */
/* Main Applicaiton Ends */
 
void DelayFor18TCY(void){
    Delay10TCYx(20);
}
void DelayPORXLCD(void){
    Delay1KTCYx(30);
}
void DelayXLCD(void){
    Delay1KTCYx(10);
}

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[Sarit]

RE: Alexan_e

Reason: added SYNTAX tags

  /*Main Loop*/
    while (1) {
        memset(dht_dat, 0x0, sizeof (dht_dat));
        read_dht(); // Check dht_dat variable after this funciton
        dht11_crc = dht_dat[0] + dht_dat[1] + dht_dat[2] + dht_dat[3]; // check check_sum
 
        if (dht_dat[4] != dht11_crc || GlobalErr>0) {
            sprintf(t,"CRC ERR :%02x!%02X   ", dht_dat[4], dht11_crc);
            sprintf(n,"Resp. Err:%d   ", GlobalErr);
 
            putrsXLCD(t);         //Display humidity on the screen
            while(BusyXLCD());
            WriteCmdXLCD(0xC0);
            while(BusyXLCD());
            putsXLCD(n);           //Display the Temperature on the screen
 
        } else {
            sprintf(Buffer,"HUMI RH :%d.%d %%  ", dht_dat[0], dht_dat[1]);
             sprintf(Buffer1,"TEMP    :%d.%d %cC  ", dht_dat[2], dht_dat[3], 223);
 
            putrsXLCD(Buffer);         //Display "Voltage" on the screen
            while(BusyXLCD());
            WriteCmdXLCD(0xC0);
            while(BusyXLCD());
            putsXLCD(Buffer1);              //Display the Temperature on the screen
            putrsXLCD("   ");           // Clear after comma
            WriteCmdXLCD(0x02);
        }

The part you highlighted was to convert the humidity and the temperature value to a string the dispay the to the lcd. I'm just a begginer in MCU programming, assist me the simpliest way possible