Revision 0:a8a0b59c162b, committed 2011-07-03

Comitter:

ddamato31

Date:

Sun Jul 03 09:55:18 2011 +0000

Commit message:

DC Motor Speed Control (No QEI Library)

Changed in this revision

diff -r 000000000000 -r a8a0b59c162b main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sun Jul 03 09:55:18 2011 +0000
@@ -0,0 +1,105 @@
+#include "mbed.h"
+#include "QEI.h"
+
+// Initialize motor PWM signal period and pulsewidth
+PwmOut speed(p22);
+DigitalIn  SetSpeed(p20);
+Timer t;
+QEI encoder (p29, p30, NC, 18);
+Serial pc(USBTX, USBRX); // tx, rx
+
+int main() {
+
+// Initialize motor PWM signal period and pulsewidth
+    speed.period_us(100000);                                //Experimented to find these numbers
+    speed.pulsewidth_us(10000);
+
+// Start motor forward at 25% speed
+        int s; s = 25000;
+        speed.pulsewidth_us(s);
+
+// Aquire set point from user
+        int DutyCycle;
+        while ( (DutyCycle < 25) || (DutyCycle > 100) ){     // Experimented to determine this range
+            pc.printf("Enter a desired duty cycle between 25%% and 90%% as an interger.\n\n");
+            pc.scanf("%i", &DutyCycle);
+        }
+        
+        pc.printf("Duty cycle set to %i%%\n\n", DutyCycle);
+        s = (DutyCycle * 1000);   
+        speed.pulsewidth_us(s);
+        wait(1);
+
+// Motor RPM average initialization and index
+        float rpm[5] = {0.0, 0.0, 0.0, 0.0, 0.0};
+        int i; i = 0;
+        
+// Start program loop
+   while(1) {
+
+// Index and reset Motor Average Counter
+        if(i > 4)
+           i = 0;
+                           
+// Revolutions per minute
+        t.start();
+          encoder.reset();                             // requires 1_us to execute
+          wait_ms(100);                                // requires 9.062_ms to execute
+          int pulse10ms = encoder.getPulses();         // requires 3.152 ms to execute for small numbers of pulses (i.e. < 10,000
+        t.stop();  
+          pc.printf("Pulses Count is %i in %f ms\n", pulse10ms, t.read()*1000);    // requires 13.542 ms to excute
+          rpm[i] = (60*pulse10ms)/(2*18*t.read());
+          float avgrpm = (rpm[0] + rpm[1] + rpm[2] + rpm[3] + rpm[4]) / 5 ;
+          pc.printf("Motor RPM %i= %f\n   AVGRPM  = %f\n\n", i, rpm[i], avgrpm);
+          ++i;
+        t.reset();
+          wait(1);
+
+/* Speed Control of Motor  ****(CHANGE TO LINE COMMENT TO ADD SPEED CONTROL)******
+
+// Build DC Motor Table and enter values into variables on the next line
+        
+        int rpm20 = , rpm100 = , rpm60 = , rpm70 = , dcY = , rpmLimit = 250;
+        int SetSpeed; 
+        static int j = 1;
+        
+        if(j > 0){
+            while ( (SetSpeed < rpm60) || (SetSpeed > rpm70) ){   
+                pc.printf("Enter a desired RPM between %i and %i as an interger.\n", rpm60, rpm70);
+                pc.scanf("%i", &SetSpeed);
+                pc.printf("RPM Set Point= %i rpm \n\n", SetSpeed);
+                DutyCycle = (80 * SetSpeed / (rpm100 - rpm20)) - dcY;   // y = m*x + b (linear motor curve
+                pc.printf("Approx Duty Cycle = %i us \n", DutyCycle);
+                s = (DutyCycle * 1000);
+                pc.printf("Inital Pulse Width = %i us \n\n", s);
+                wait(2);
+            }
+        }
+        j = 0;
+        if ( avgrpm < (SetSpeed - rpmLimit)) {
+            DutyCycle = (DutyCycle + 1);
+            s = (DutyCycle * 1000);
+            pc.printf("Increase Duty Cycle= %i%%\n", DutyCycle);
+            pc.printf("Pulse Width = %i us \n\n", s);
+            speed.pulsewidth_us(s);
+            }
+        else if ( avgrpm > (SetSpeed + rpmLimit)){
+            DutyCycle = (DutyCycle - 1);
+            s = (DutyCycle*1000);
+            pc.printf("Decrease Duty Cycle= %i%%\n", DutyCycle);
+            pc.printf("Pulse Width = %i us \n\n", s);
+            speed.pulsewidth_us(s);
+            }
+        else if ( (avgrpm > (SetSpeed - rpmLimit)) || (avgrpm < (SetSpeed + rpmLimit)) ) {
+            s = DutyCycle * 1000;
+            pc.printf("Stable Duty Cycle= %i%%\n", DutyCycle);
+            pc.printf("Pulse Width = %i us \n\n", s);
+            }
+        else
+            
+    return 0;                                                                              
+     
+*/ //****(CHANGE TO LINE COMMENT TO ADD SPEED CONTROL) 
+    
+    }       
+}

diff -r 000000000000 -r a8a0b59c162b mbed.bld
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Sun Jul 03 09:55:18 2011 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/63bcd7ba4912