pic16f877-dht11-SendingStartSignal

// Send start signal to the sensor
void Start_Signal(void) {
    DHT11_PIN_DIR = 0;     // Configure as output
    DHT11_PIN = 0;         // Pull data line low
    __delay_ms(25);        // Wait 25ms
    DHT11_PIN = 1;         // Release data line
    __delay_us(30);        // Wait 30us
    DHT11_PIN_DIR = 1;     // Configure as input
}

// Check sensor response
unsigned char Check_Response(void) {
    TMR1H = 0;                  // Reset Timer1
    TMR1L = 0;
    TMR1ON = 1;                 // Enable Timer1 module
    
    while(!DHT11_PIN && TMR1L < 100);  // Wait for DHT11_PIN to go high (80s low time)
    
    if(TMR1L > 99)              // If response time > 99s
        return 0;               // Return 0 (response error)
    
    TMR1H = 0;                  // Reset Timer1
    TMR1L = 0;
    
    while(DHT11_PIN && TMR1L < 100);   // Wait for DHT11_PIN to go low (80s high time)
    
    if(TMR1L > 99)              // If response time > 99s
        return 0;               // Return 0 (response error)
    
    return 1;                   // Return 1 (response OK)
}