main.cpp

00001 #include "mbed.h"
00002 #include "encoder.h"
00003 #include "MODSERIAL.h"
00004 
00005 /*******************************************************************************
00006 *                                                                              *
00007 *   Code can be found at http://mbed.org/users/vsluiter/code/BMT-K9-Regelaar/  *
00008 *                                                                              *
00009 ********************************************************************************/
00010 
00011 /** keep_in_range -> float in, and keep_in_range if less than min, or larger than max **/
00012 void keep_in_range(float * in, float min, float max);
00013 
00014 /** variable to show when a new loop can be started*/
00015 /** volatile means that it can be changed in an    */
00016 /** interrupt routine, and that that change is vis-*/
00017 /** ible in the main loop. */
00018 
00019 volatile bool looptimerflag;
00020 
00021 /** function called by Ticker "looptimer"     */
00022 /** variable 'looptimerflag' is set to 'true' */
00023 /** each time the looptimer expires.          */
00024 void setlooptimerflag(void)
00025 {
00026     looptimerflag = true;
00027 }
00028 
00029 
00030 int main() {
00031     //LOCAL VARIABLES 
00032     /*Potmeter input*/
00033     AnalogIn potmeter(PTC2);
00034     /* Encoder, using my encoder library */
00035     /* First pin should be PTDx or PTAx  */
00036     /* because those pins can be used as */
00037     /* InterruptIn                       */
00038     Encoder motor1(PTD0,PTC9);
00039     /* MODSERIAL to get non-blocking Serial*/
00040     MODSERIAL pc(USBTX,USBRX);
00041     /* PWM control to motor */
00042     PwmOut pwm_motor(PTA12);
00043     /* Direction pin */
00044     DigitalOut motordir(PTD3);
00045     /* variable to store setpoint in */
00046     float setpoint;
00047     /* variable to store pwm value in*/
00048     float pwm_to_motor;
00049     //START OF CODE
00050     
00051     /*Set the baudrate (use this number in RealTerm too! */
00052     pc.baud(230400);
00053     
00054    /*Create a ticker, and let it call the     */
00055    /*function 'setlooptimerflag' every 0.01s  */
00056     Ticker looptimer;
00057     looptimer.attach(setlooptimerflag,0.01);  
00058     /* Oops... I left some test code in my program */
00059     pc.printf("bla");
00060     
00061     //INFINITE LOOP 
00062     while(1) {
00063         /* Wait until looptimer flag is true. */
00064         /* '!=' means not-is-equal            */
00065         while(looptimerflag != true);
00066         /* Clear the looptimerflag, otherwise */
00067         /* the program would simply continue  */
00068         /* without waitingin the next iteration*/
00069         looptimerflag = false;
00070         
00071         /* Read potmeter value, apply some math */
00072         /* to get useful setpoint value         */
00073         setpoint = (potmeter.read()-0.5)*2000;
00074         
00075         /* Print setpoint and current position to serial terminal*/
00076         pc.printf("s: %f, %d \n\r", setpoint, motor1.getPosition());
00077         
00078         /* This is a P-action! calculate error, multiply with gain, and store in pwm_to_motor */
00079         pwm_to_motor = (setpoint - motor1.getPosition())*.001;
00080         /* Coerce pwm value if outside range          */
00081         /* Not strictly needed here, but useful       */
00082         /* if doing other calculations with pwm value */
00083         keep_in_range(&pwm_to_motor, -1,1);
00084         
00085         /* Control the motor direction pin. based on   */
00086         /* the sign of your pwm value.      If your    */
00087         /* motor keeps spinning when running this code */
00088         /* you probably need to swap the motor wires,  */
00089         /* or swap the 'write(1)' and 'write(0)' below */
00090         if(pwm_to_motor > 0)
00091             motordir.write(1);
00092         else
00093             motordir.write(0);
00094         //WRITE VALUE TO MOTOR
00095         /* Take the absolute value of the PWM to send */
00096         /* to the motor. */  
00097         pwm_motor.write(abs(pwm_to_motor));
00098     }
00099 }
00100 
00101 
00102 //coerces value 'in' to min or max when exceeding those values
00103 //if you'd like to understand the statement below take a google for
00104 //'ternary operators'.
00105 void keep_in_range(float * in, float min, float max)
00106 {
00107     *in > min ? *in < max? : *in = max: *in = min;
00108 }
00109 
00110 
00111