Diff: main.cpp

Revision:

2:1c669cb14c5b

Parent:

1:b5c4ca3bf074

Child:

3:ce5582846693

--- a/main.cpp	Tue Feb 28 20:11:55 2017 +0000
+++ b/main.cpp	Tue Feb 28 20:20:49 2017 +0000
@@ -1,6 +1,6 @@
 /* ELEC1620 Application Board Example
 
-TMP36
+LDR
 
 (c) Dr Craig A. Evans, University of Leeds, Feb 2017
 
@@ -12,8 +12,8 @@
 // JP1 on board must be in 2-3 position
 N5110 lcd(p8,p9,p10,p11,p13,p21);
 
-// Temperature sensor connected to ADC pin
-AnalogIn tmp36(p16);
+// LDR connected to ADC pin
+AnalogIn ldr(p15);
 
 int main() {
     
@@ -21,24 +21,25 @@
     
     while(1) {
         
-        // read in the ADC value and convert to voltage
-        float voltage = 3.3f * tmp36.read();
+        // clear the display at the start of every new frame
+        lcd.clear();
         
-        // T = 100V - 50
-        // convert voltage to temperature
-        float temperature = 100.0f*voltage - 50.0f;
+        // lcd is 84 pixels wide x 48 pixels high
+        
+        //  x, y,  width, height, outline
+        lcd.drawRect(12,20,60,8,0);
         
-        // we need an array of chars to store the message
-        char buffer[14];  // max screen witdth is 14
-        // print message to buffer
-        sprintf(buffer,"T=%.2f C",temperature);
-        // print to screen (x pixel, line number)
-        lcd.printString(buffer,0,0);
+        float value = ldr.read();  // read in the LDR value in range 0.0 to 1.0
+        
+        int width = int(value*60.0f); // convert to an int in the range 0.0 to 60.0
+        
+        // draw a bar of the correct width
+        lcd.drawRect(12,20,width,8,1); // the 1 makes a black rectangle
+        
         // update the LCD
         lcd.refresh(); 
-        
         // small delay between readings
-        wait(1.0);
+        wait(0.2);
         
     }
 }