Diff: main.cpp

Revision:

7:a4f884972a0e

Parent:

4:07dd82e3f934

Child:

8:a5b18dfe684f

--- a/main.cpp	Sun Aug 25 18:01:58 2013 +0000
+++ b/main.cpp	Wed Nov 11 08:12:13 2015 +0000
@@ -1,47 +1,64 @@
-#include "ComparatorIn.h"
-#include "mbed.h"
+/** comparatorin_demo
+ *  Simple program to demonstrate the basic functions
+ *  of the analog comparator of the FRDM-KL25Z board.
+ *
+ *  Used library:
+ *   - ComparatorIn //https://developer.mbed.org/users/frankvnk/code/ComparatorIn/
+ *     written by Frank Vannieuwkerke
+ *
+ *  Hardware requirements:
+ *   - FRDM-KL25 board
+ *   - CdS photoresistor pulled up by 10 k
+ *   - Connecect the midpoint of the divider to PTE29
+ *
+ *            10k          CdS photoresistor
+ *   +3.3V --/\/\/\---+---/\/\/\---- GND
+ *                    |
+ *                  PTE29
+ *
+ */
 
-DigitalOut blinker (LED_BLUE);
-DigitalOut cmpled (LED_GREEN);
-DigitalOut cmp_en (PTD5);
-AnalogIn cmp_lvl (PTB0);
-ComparatorIn compi(PTC8, PTE30); // in+ = PTC8, in- = 12-bit DAC 
-
-// Comparator callback functions
+#include "mbed.h"
+#include "ComparatorIn.h"
+ 
+DigitalOut blinker (LED_BLUE);      // blinking LED
+DigitalOut cmpled (LED_GREEN);      // signing comparator status
+AnalogIn cmp_lvl (PTE29);           // ADC input to check comparator input
+ComparatorIn compi(PTE29, PTE30);   // in+ = PTE29, in- = 12-bit DAC 
+ 
+// Comparator interrupt callback functions
 void cmp_rise_ISR(void)
 {
-    cmpled = 0;
+    cmpled = 0;                     // LED ON at rising edge
 }
-
+ 
 void cmp_fall_ISR(void)
 {
-    cmpled = 1;
+    cmpled = 1;                     // LED OFF at falling edge
 }
-
-
-
+ 
+ 
+ 
 int main()
 {
-    cmp_en = 1;
-    cmpled = 1;
-
-    compi.rising(&cmp_rise_ISR);                // Set pointer to rising interrupt function
-    compi.falling(&cmp_fall_ISR);               // Set pointer to falling interrupt function
-    compi.treshold(0.3);                        // Set comparator threshold to 1V = 0.3 * 3.3V
-
+    cmpled = 1;                     // LED OFF at the beginning
+ 
+    compi.rising(&cmp_rise_ISR);    // Set pointer to rising interrupt function
+    compi.falling(&cmp_fall_ISR);   // Set pointer to falling interrupt function
+    compi.treshold(0.3);            // Set comparator threshold to 1V = 0.3 * 3.3V
+ 
     while(1)
     {
         printf("Light sensor : %7.5f Volt\n",cmp_lvl*3.3);
-        blinker = 1;
-        wait(1);
-        blinker = 0;
+        blinker = 1;                // binking LED OFF
+        wait(2);                    // wait for 2 sec
+        blinker = 0;                // blinking LED ON
         wait(0.2);
-        if (compi.status() == 0x01)
+        if (compi.status() == 0x01) // poll comparator status
         {
             printf("*** Treshold reached : %7.5f\n",cmp_lvl*3.3);
         }
     }
 }
-
-
-
+ 
+