main.cpp

00001 #include "mbed.h"
00002 #include "TextLCD.h"
00003 
00004 PwmOut motor(p21);   //Control the speed of the fan 
00005 DigitalInOut DHT11(p5); // Activate digital in as dht11 Pin
00006 TextLCD lcd(p6, p7, p14, p15, p16, p17); // rs, e, d4-d7
00007 
00008 
00009 Timer tmr; //initialize timer
00010 uint64_t adat; // 64 bit variable for temporary data
00011 int i;
00012 void dht_read(void) {
00013     DHT11.output(); // Set p5 as output
00014     // Initialize measurement > 18 ms low
00015     DHT11 = 0;
00016     wait_ms(20);
00017     // After high and release the pin switch input mode
00018     DHT11 = 1;
00019     DHT11.input();
00020     // Wait until the end of 80 us low
00021     while(!DHT11.read()) {}
00022     // Wait until end of 80 us high
00023     while(DHT11.read()) {}
00024     // 40 bit, 40 read out cycle
00025     for(i=0; i<40; i++) {
00026         adat = adat << 1; // Shift for new number
00027         tmr.stop(); // Stop timer if runs
00028         tmr.reset();  // Reset timer
00029         // Wait until pin
00030         while(!DHT11.read()) {}          
00031         tmr.start();            
00032         while(DHT11.read()) {}
00033         // If DHT11 HIGH longer than 40 micro seconds (hopefully 70 us)
00034         if(tmr.read_us() > 40) {
00035             // bit is 1
00036             adat++;
00037         }
00038     }
00039 }
00040 
00041 int main() {
00042     while(1) {
00043             adat = 0;
00044             motor.period(0.010);
00045             dht_read(); // Call the function   
00046             int tem = (adat & 0x0000000000ff0000) >> 16;            
00047             lcd.printf("Temperature:");
00048             lcd.printf("%d\n",tem);     // Temperature       
00049             if(tem <= 20){
00050                 motor = 0; 
00051                 lcd.locate(4,1);
00052                 lcd.printf("Fan OFF");
00053             }
00054             else if(tem > 20 && tem <= 22) {
00055                 motor = 0.2;   
00056                 lcd.printf("Fan Speed:");
00057                 lcd.locate(12,1);  
00058                 lcd.printf("20%");
00059             }
00060             else if(tem > 22 && tem <= 24) {
00061                 motor = 0.4;
00062                 lcd.printf("Fan Speed:");
00063                 lcd.locate(12,1);  
00064                 lcd.printf("40%");                  
00065             }
00066             else if(tem > 24 && tem <= 26) {
00067                 motor = 0.6;
00068                 lcd.printf("Fan Speed:");
00069                 lcd.locate(12,1);  
00070                 lcd.printf("60%");    
00071             }
00072             else if(tem > 26 && tem <= 28) {
00073                 motor = 0.8;
00074                 lcd.printf("Fan Speed:");
00075                 lcd.locate(12,1);  
00076                 lcd.printf("80%");    
00077             }
00078             else {
00079                 motor = 1;
00080                 lcd.printf("Fan Speed:");
00081                 lcd.locate(12,1);  
00082                 lcd.printf("100%");   
00083             }
00084             wait(2); // Wait 2 sec till continue.
00085             lcd.cls(); // Clear the screen
00086     }
00087 }