File content as of revision 0:c1245c18d07e:

#include "mbed.h"

//#include "uLCD_4DGL.h"

Serial pc(USBTX, USBRX);

InterruptIn chA(p26);
InterruptIn chB(p25);
int chanA;
int chanB;
int currState;
int prevState;
int change;


//uLCD_4GDL uLCD(p9,p10,p11);
volatile int count1 = 0;
//volatile int count2 = 0;
InterruptIn pb(p21);
DigitalOut led(LED1);


/*
Implemented barebones version of "QEI.h" by Aaron Berk for the sake of
understanding the concept of X4 encoding
00 01 11 10 00
4 different states
*/

void encode() {
    change = 0;
    chanA  = chA.read();
    chanB  = chB.read();
    currState = (chanA << 1) | (chanB);
    if (((currState ^ prevState) != 0x3) && (currState != prevState)) {
        // example 01 <- 11
        // change = (11&01 = 01) ^ (01&10 = 00>>1) = 1
        // example 10 -> 00
        // change = (10&01 = 00) ^ (00&10 = 00>>1) = 0
        // change = (if(left)    ^

        change = (prevState & 0x1) ^ ((currState & 0x2) >> 1);
        if (change == 0) {
            change = -1;
        }
        count1 += change;
    }
    prevState = currState;
}
void clear() {
    //uLCD.cls();
    led = !led;
}

int main() {
    chA.mode(PullUp);
    chB.mode(PullUp);

    chanA = chA.read();
    chanB = chB.read();
    currState = (chanA << 1) | (chanB);
    prevState = currState;
    chA.rise(&encode);
    chA.fall(&encode);
    chB.rise(&encode);
    chB.fall(&encode);


    pb.mode(PullUp);
    pb.fall(&clear); //pb to clear screen
    //add a pb to turn on and off pen
    //add a pot to go through colors
    //have something display current color and RGB val
    while(1) {
        /*if(count1 < 0) {
            pc.printf("CW \n\r");
        } else {
            pc.printf("CCW \n\r");
        }*/

        pc.printf("count1: %d\r\n", count1);
        pc.printf("change: %d\r\n", change);
        pc.printf("---------\r\n");
        wait(.1);
    }
}