Diff: main.cpp

Revision:

4:2ad0cc818166

Parent:

3:c9c1c0ebf89d

--- a/main.cpp	Wed Oct 09 09:43:49 2013 +0000
+++ b/main.cpp	Wed Oct 09 10:27:29 2013 +0000
@@ -11,8 +11,16 @@
 /** keep_in_range -> float in, and keep_in_range if less than min, or larger than max **/
 void keep_in_range(float * in, float min, float max);
 
+/** variable to show when a new loop can be started*/
+/** volatile means that it can be changed in an    */
+/** interrupt routine, and that that change is vis-*/
+/** ible in the main loop. */
+
 volatile bool looptimerflag;
 
+/** function called by Ticker "looptimer"     */
+/** variable 'looptimerflag' is set to 'true' */
+/** each time the looptimer expires.          */
 void setlooptimerflag(void)
 {
     looptimerflag = true;
@@ -21,31 +29,71 @@
 
 int main() {
     //LOCAL VARIABLES 
+    /*Potmeter input*/
     AnalogIn potmeter(PTC2);
-    Encoder motor1(PTD0,PTC9);//first pin on PTAx or PTDx
+    /* Encoder, using my encoder library */
+    /* First pin should be PTDx or PTAx  */
+    /* because those pins can be used as */
+    /* InterruptIn                       */
+    Encoder motor1(PTD0,PTC9);
+    /* MODSERIAL to get non-blocking Serial*/
     MODSERIAL pc(USBTX,USBRX);
+    /* PWM control to motor */
     PwmOut pwm_motor(PTA12);
+    /* Direction pin */
     DigitalOut motordir(PTD3);
+    /* variable to store setpoint in */
     float setpoint;
+    /* variable to store pwm value in*/
     float pwm_to_motor;
     //START OF CODE
+    
+    /*Set the baudrate (use this number in RealTerm too! */
     pc.baud(230400);
+    
+   /*Create a ticker, and let it call the     */
+   /*function 'setlooptimerflag' every 0.01s  */
     Ticker looptimer;
     looptimer.attach(setlooptimerflag,0.01);  
+    /* Oops... I left some test code in my program */
     pc.printf("bla");
+    
     //INFINITE LOOP 
     while(1) {
+        /* Wait until looptimer flag is true. */
+        /* '!=' means not-is-equal            */
         while(looptimerflag != true);
+        /* Clear the looptimerflag, otherwise */
+        /* the program would simply continue  */
+        /* without waitingin the next iteration*/
         looptimerflag = false;
+        
+        /* Read potmeter value, apply some math */
+        /* to get useful setpoint value         */
         setpoint = (potmeter.read()-0.5)*2000;
+        
+        /* Print setpoint and current position to serial terminal*/
         pc.printf("s: %f, %d \n\r", setpoint, motor1.getPosition());
+        
+        /* This is a P-action! calculate error, multiply with gain, and store in pwm_to_motor */
         pwm_to_motor = (setpoint - motor1.getPosition())*.001;
+        /* Coerce pwm value if outside range          */
+        /* Not strictly needed here, but useful       */
+        /* if doing other calculations with pwm value */
         keep_in_range(&pwm_to_motor, -1,1);
+        
+        /* Control the motor direction pin. based on   */
+        /* the sign of your pwm value.      If your    */
+        /* motor keeps spinning when running this code */
+        /* you probably need to swap the motor wires,  */
+        /* or swap the 'write(1)' and 'write(0)' below */
         if(pwm_to_motor > 0)
-            motordir = 1;
+            motordir.write(1);
         else
-            motordir = 0;
-        //WRITE VALUE TO MOTOR  
+            motordir.write(0);
+        //WRITE VALUE TO MOTOR
+        /* Take the absolute value of the PWM to send */
+        /* to the motor. */  
         pwm_motor.write(abs(pwm_to_motor));
     }
 }