main.cpp

00001 #include "mbed.h"
00002 #include "QEI.h"
00003 #include "MODSERIAL.h"
00004 //#include <"math.h">
00005 
00006 QEI motor1(D13,D12,NC, 624);
00007 MODSERIAL pc(USBTX,USBRX);
00008 DigitalOut direction1(D7);
00009 PwmOut speed1(D6);
00010 DigitalIn button1(PTC6);
00011 
00012 int main()
00013 {
00014    DigitalOut led(LED_RED);
00015    pc.baud(115200);
00016    int activation=0;//int for starting calibration
00017    float cycle = 0.6;//define the speed of the motor
00018    int first = 0;
00019    while(1){
00020        if (button1.read()==0){
00021        activation = 1;//acivate the int if the button is pressed
00022        }
00023     
00024     //pc.printf("%d\n",activation);//test if the button is activated
00025     //wait(1);
00026     
00027    if(activation == 1){
00028        DigitalOut led(LED_BLUE);
00029        direction1.write(false);//turn motor CCW or CW if set to 0
00030    //motor CW = 0
00031    //motor CCW = 1
00032        speed1.period_us(100);//Set period of PWM to 100 us.
00033        speed1.write(cycle);//write the speed to the motor
00034             
00035        
00036        if(first==0){//on the first loop wait a moment for the motor to start.
00037            wait(3);
00038            first=1;
00039            }
00040            //set up the speed calculation of the motor
00041        wait(0.1);
00042        int pos1=motor1.getPulses();
00043        //pc.printf("position 1 is: %d\n",pos1);//print position 1
00044        wait(0.1);
00045        int pos2=motor1.getPulses();
00046        //pc.printf("position 2 is: %d\n",pos2);//print position 1
00047        int diff = pos2 - pos1;//check if the encoder count stops changing
00048        int rads = abs(diff/0.1);
00049        pc.printf("the speed is : %d counts/second\n", rads);//print out the speed
00050        if(diff == 0){
00051            cycle=0;//speed of 0 to stop motor
00052            speed1.write(cycle);//write the new speed to the motor
00053            motor1.reset();//reset the motor position
00054            int posnew=motor1.getPulses();
00055            pc.printf("The new position is: %d\n",posnew);
00056            activation=0;
00057            break;
00058        }
00059        }
00060 }
00061 }
00062        //determine speed of movement from the encoder signal
00063        // the amount of counts for one revolution is 32
00064        //this is X2 encodng, as the QEI uses X2 by default 
00065        //and the motor encoder has a X4 encoder and thus 64 counts per revolution
00066        //thus keeping in mind the gearbox with 1:131,25 gear ratio:
00067        // the amount of counts for a gearbox revolution or resolution is 8400
00068        // a revolution is 2 pi rad, resolution is : 8400/2 pi = 1336.90 counts/rad
00069        //or for the encoder x2 its 668,45 counts/rad
00070  /*      
00071    Rotational position in degrees can be calculated by:
00072  *
00073  * (pulse count / X * N) * 360
00074  *
00075  * Where X is the encoding type [e.g. X4 encoding => X=4], and N is the number
00076  * of pulses per revolution.
00077  *
00078  * Linear position can be calculated by:
00079  *
00080  * (pulse count / X * N) * (1 / PPI)
00081  *
00082  * Where X is encoding type [e.g. X4 encoding => X=44], N is the number of
00083  * pulses per revolution, and PPI is pulses per inch, or the equivalent for
00084  * any other unit of displacement. PPI can be calculated by taking the
00085  * circumference of the wheel or encoder disk and dividing it by the number
00086  * of pulses per revolution.
00087  
00088      * Reset the encoder.
00089      *
00090      * Sets the pulses and revolutions count to zero.
00091      
00092     void reset(void);
00093  */
00094