Diff: main.cpp

Revision:

12:6e13c34c4295

Parent:

11:e563823d3c94

Child:

13:d9d0eb9103d3

--- a/main.cpp	Wed Mar 01 03:10:29 2017 +0000
+++ b/main.cpp	Sat Apr 15 13:44:24 2017 +0000
@@ -1,4 +1,21 @@
-///setup code for encoder on pins PA0 and PA1 (A0 and A1)///
+
+
+/***
+Basic Program Flow:
+mbed turns on. initializes.
+enters main while loop then first sub while loop where it listens for a go command
+mbed recieves go commmand, initializes for data collection, breaks out of first sub while
+    enters second sub while. starts collecting and publishing data, listening for stop
+mbed hears stop, breaks out of second while loop, returns back to first while loop
+
+
+Keep in Mind:
+Serial communication between mbed matlab sometimes sucks, and often breaks down
+Most of the things in this program (and the corresponding matlab one) are meant
+to minimize the amount of bad data that gets passed over serial and maintain the
+connection.
+***/
+
 
 #include "mbed.h"
 #include "time.h"
@@ -7,22 +24,36 @@
 
 #define PI 3.14159265358979323846
 
+
+//Just for basic debugging
+//User button controls motor speed
+//Green LED should turn on while listening to pc for input before starting run
 InterruptIn button(USER_BUTTON);
-PwmOut pwm(D5);//do not use D3
-DigitalOut a(D2);
-DigitalOut b(D4);
-
-AnalogIn currentSense(A5); //hook up to Vout on current sensor
-Serial pc(USBTX, USBRX, 115200);
 DigitalOut green(LED2);
 
-const int CPR = 900*4;  // Encoder counts per revolution.  Change to match your encoder. x4 for quadrature!
-const double VREF = 3; //Microcontroller reference voltage
-const float currentSensorOutputRatio = 0.185; // Volts/Amp. Divide Voltage by cSenseOutput to get current
-const float PSupply_Voltage = 12.0;
-const float Output_Voltage = 6.0;
+// Pololu VNH5019 Motor Driver Carrier. https://www.pololu.com/product/1451
+PwmOut pwm(D5);     //pwm input on motor controller. do not use D3
+DigitalOut a(D2);   //IN_A input on motor controller
+DigitalOut b(D4);   //IN_B input on motor controller
+
+//Hook up to Vout on current sensor
+//SparkFun Hall-Effect Current Sensor Breakout - ACS712
+//https://www.sparkfun.com/products/8882
+AnalogIn currentSense(A5);
+
+//For communication with pc through matlab
+//Make sure baud rates are equal
+Serial pc(USBTX, USBRX, 115200);
+
+const int CPR = 900*4;  // Encoder counts per revolution (900).  Change to match your encoder. x4 for quadrature
+const double VREF = 3;  // Microcontroller reference voltage
+const float currentSensorOutputRatio = 0.185;   // Volts/Amp specified by current sensor. Divide Voltage by cSenseOutput to get current
+const float PSupply_Voltage = 12.0;             // Voltage input from powersupply
+const float Output_Voltage = 6.0;               // Maximum output voltage desired
 const float pwm_pulley = Output_Voltage/PSupply_Voltage;
 
+
+///setup code for encoder on ***** pins PA0 and PA1 (A0 and A1) ****** ///
 void EncoderInitialise(void) {
     // configure GPIO PA0 & PA1 as inputs for Encoder
     RCC->AHB1ENR |= 0x00000001;  // Enable clock for GPIOA
@@ -77,20 +108,27 @@
 
 int main() {
     
-    int endcount, startcount;
-    double time_between_readings;
-    double velocity;
+    int endcount, startcount;       // encoder counts
+    double time_between_readings;   // between encoder readings
+    double velocity;                // radians/time
     double currentSensed = 0;
     clock_t start, end, absoluteStart;
-    int ticks;
-    a=1; b=0; pwm.write(0);
-    button.fall(&pressed);
-    double updatePeriod = 0.01; /* must select carefully */
-    double publishFrequency = 0.05; /* seconds. rate to publish to matlab */
-    double samplesPerPublish = (int)(publishFrequency/updatePeriod); /*this improves time response of filter and maintains smoothness*/
+    int ticks;                      // ticks counted on encoder
+    a=1; b=0; pwm.write(0);         // this is forward. you can change a and b on a rig if it's turning the wrong way!
+    button.fall(&pressed);          //adds pressed callback upon button push
+    
+    /*  we don't send all the information to matlab all the time. some collection and smoothing is done
+        here in order to not overload matlab with input making it slow. And to take a lot of data so we
+        can do smoothing quickly on this side */
+    double updatePeriod = 0.01;  /* must select carefully. too fast and you don't get enough encoder ticks*/
+    double publishFrequency = 0.05; /* seconds. rate to publish to matlab. no need to overload matlab with input*/
+    double samplesPerPublish = (int)(publishFrequency/updatePeriod);
     int publishCounter = 1;
-    double filterRatio = 0.1;
-    double currentFilterRatio = 0.035;
+    
+    double filterRatio = 0.1;           // on the speed data
+    double currentFilterRatio = 0.035;  // on the current data
+    
+    /* the current sensor has some resting value. record and subtract that out */
     float currentSensorOffset = 0; int i; 
     for(i=1;i<301;i++){ currentSensorOffset += currentSense.read(); }
     currentSensorOffset = currentSensorOffset*VREF/300;
@@ -101,7 +139,7 @@
     while(1) {
     
 
-        while(1) {
+        while(1) {                                  // listen for pc go command
             
             green = true;
             if(pc.readable()) {
@@ -115,8 +153,17 @@
                     startcount = 0;
                     endcount = 0;
                     currentSensed = 0;
-                    pwm.write(pwm_pulley);
-                    break; 
+                    pwm.write(pwm_pulley);  
+                    break;
+                    // note: it's really easy to change this if we want to include
+                    // variable speed input from the command in the future.
+                    // it's easiest to just pass chars as serial input when the
+                    // mbed is listening (I find it's the most reliable)
+                    // so an easy way would just be to pass a 1 2 3 ... 9 0
+                    // corresponding to some percentage of the max output voltage
+                    // as the start value for the run
+                    // ask me for previous pulley interface mbed and matlab code
+                    // where I have that implimented
                 }
             }
         
@@ -125,7 +172,7 @@
         }  
     
     
-        while(1) {
+        while(1) {                          //start collecting and publishing data
             
             green = false;
             wait(updatePeriod);
@@ -137,9 +184,11 @@
             ticks = endcount-startcount;
             if(abs(ticks)>CPR/2) /***** for rollover case: *****/
             { ticks = ((ticks<0)-(ticks>0))*(CPR-abs(ticks)); }
+            
             velocity = filterRatio*((double)ticks)/CPR*2*PI/time_between_readings + (1-filterRatio)*velocity; /* with filtering*/
             currentSensed = currentFilterRatio*((double)currentSense.read()*VREF-currentSensorOffset) + (1-currentFilterRatio)*currentSensed;
-            if(pc.readable())
+            
+            if(pc.readable())                   //pc will send r (reset) when run is finished
             {
                 char charIn = pc.getc();
                 if(charIn == 'r'){
@@ -148,9 +197,9 @@
                     break;
                 }
             }        
-            if(publishCounter == samplesPerPublish) {
+            if(publishCounter == samplesPerPublish) {                           //only publish onece every samplesPerPublish
                 printf("%+9.5f,%+8.4f,%+9.4f,%+8.2f\n", currentSensed/currentSensorOutputRatio, pwm.read(), velocity, ((double)(end-absoluteStart)/CLOCKS_PER_SEC));
-                publishCounter = 1;  // good for 1000 seconds. and room to grow one power of 10 on all other inputs.  //just changed velocity to 4 precision to give it extra room for no load? bug maybe?
+                publishCounter = 1;  //output formatting very important. running a simple string length checksum on matlab side to discard bad data
             }
             publishCounter++;