File content as of revision 3:502f90649834:

// Firmware to demonstrate typical "Tank-Drive" robot motor control.
// one left motor, and one right motor.
//
// Can do simple commanding from a bluetooth terminal (like Android's BlueTerm),
// or from the Android app used in http://www.instructables.com/id/Simple-RC-car-for-beginners-Android-control-over-/
//
// The FreeScale FRDM-K64F is a much more powerful board than needed for this task,
// but it is a good template for a typical "tank-drive" robot based on the FRDM-K64F.
//
// The DBH-1x motor driver has very similar inputs to the very common L298N
// dual-H-bridge driver chip.  One main difference is that it warns that
// the drive is to be used at no more than 98% PWM.  In order
// to meet this extra requirement over common L298 motor driver logic,
// the direction indicator inputs are PWM at 98% instead of logic "1"
//
// Aaron Birenboim, http://boim.com    31jul2015
// Apache license

#include "mbed.h"

//DigitalOut gpo(D0);
//DigitalOut led(LED_RED);
//PwmOut ENA( PTD1);   // D13 on Arduino Shield
//PwmOut IN1A(PTD3);  // D12 on Arduino Shield
//PwmOut IN2A(PTD2);  // D11 on Arduino Shield
//PwmOut ENB( PTD0);   // D13 on Arduino Shield
//PwmOut IN1B(PTC4);  // D12 on Arduino Shield
//PwmOut IN2B(PTA0);  // D11 on Arduino Shield

Timer Time;
inline int millis() {return(Time.read_ms());} // mimic Arduino millis() function

// Tried to inherit/polymorph serial capabilities...  but could
// not get to compile... or get access to mbed::stream capabilities.
// I know this is sloppy...  but I'm just going to make a global
// Serial, and let otherclasses have a reference to it.
#include "Serial.h"
//Serial CmdSerial(PTC17,PTC16);  // Command/Diagnostic serial port on UART3, sicne I don't know how to use USB ports (yet)
Serial CmdSerial(PTC15,PTC14);  // Command/Diagnostic serial port on "bluetooth add-on" header
Serial DiagSerial(USBTX, USBRX);

// emulation of some Arduino serial methods.
//    this class has a singleton interrupt callback, so it
//    creates a singleton global
#include "ASerial.h"  // emulation of some common Arduino Serial methods
ASerial cSerial(CmdSerial); 
//ASerial cSerial(DiagSerial); 

// Set up motor drive for left and right motors
#define DBH1   // use DBH-1x modifications to typicsl L298 drive logic
#include "MotorDrive298.h"
// en, in1, in2, ct
MotorDrive MotL(PTD2,PTD3,PTD1,PTB2);
MotorDrive MotR(PTC3,PTC4,PTD0,PTB3);

#include "Command.h"

// ------------------------------------------------------------------------------

void initMotorDrive(MotorDrive &md)
{
    md.setCommandTimeout(15000);  // ms between commands before automatic emergency stop
    //ms.setPWMfreqHz(8000);
    
    // these should be the defaults
    //md.setStartupTime(5);  // full power pulse this long when starting from full STOP
    //md.setStopDeadTime(3000); // wait this many ms after emergency STOP before starting up again
    //md.setMinPWM(0.004f);  // any PWM command below this istreated as 0
    //md.setMaxPWM(0.98f);  // these drives can fail if attempt to run full-100%
    md.setDecelRate(500);  // deceleration rate on STOP.  This frac/ms
    
}

// Since this board has fancy tri-color LED, let's sequence it
// instead of a boring old flash for a heartbeat
DigitalOut ledR(LED_RED);
DigitalOut ledG(LED_GREEN);
DigitalOut ledB(LED_BLUE);
void toggleFlash()
{
    static int k=0;
    k++;
    if ((k<0) || (k>7)) k=0;
    // Gray code counter...
    switch(k)
    {
        case 1:
        case 5:  ledG = !ledG; break;
        case 3:
        case 7:  ledB = !ledB; break;
        default: ledR = !ledR; break;
    }
}

void reportCurrent()
{
  float cr, cl;
  cr = MotR.getCurrent();
  cl = MotL.getCurrent();
  CmdSerial.printf("\tCurrent:  left=%.3f  right=%.3f\r\n",cl,cr);
}

//void dumpSerialChar()
//{
//  int i = cSerial.getc();
//  CmdSerial.printf("%d %c\n",i,i);    
//}
    
// ================================================== main

int prevCommandTime=0;

#define FLASH_DT 800
int tFlash = 0;

// for diagnostics, just print a few messages, then be quiet to improve
// performance when in actual use.
int nMsg = 9;

int main()
{
    CmdSerial.baud(57600);
    CmdSerial.puts("\r\nTankDrive for K64F with Bluetooth\r\n\n");
    CmdSerial.attach(&gotChar);  // singleton serial character buffer
    DiagSerial.baud(115200);   DiagSerial.puts("TankDrive Diagnostics\r");
    
    // Set motor drive parameters
    initMotorDrive(MotL);
    initMotorDrive(MotR);
    
    Time.reset();
    Time.start();

    CommandReader cmd;
    
    //int detailMsg=9;    
    while (true) {
        int t = Time.read_ms();
//if(--detailMsg>0)CmdSerial.printf("%d\r\n",t);
        char code;
        int val;
        int stat = cmd.get(code,val);

        if (stat)
        {
            prevCommandTime = t;
            if (nMsg>0){nMsg--;DiagSerial.printf("\r\n\t\tcmd>%c%d\r\n",code,val);}

            switch(code)
            {
            case 'L': MotL.setSpeed(val/255.0,t); break;
            case 'R': MotR.setSpeed(val/255.0,t); break;
            default : 
                DiagSerial.printf("Unidentified command \"%c%d\" (stop)",code,val);
                MotL.stop();
                MotR.stop();
            }

//CmdSerial.puts("\nrcd\r");
//CmdSerial.puts("\r\n");
//detailMsg=2;
//CmdSerial.putc('\n');
        }
        else
        { // no command, do housekeeping (misc state update stuff)
            MotL.update(t);
            MotR.update(t);

            if ((prevCommandTime > 0x0fffff00) && (t < 999))
            {  // time counter is close to wrapping around.  make sure this does not happen.
               // I think we can tolerate a minor glitch once every 24.8 days of continuous use
               prevCommandTime = tFlash = 0;
               Time.reset();
               Time.start();
               CmdSerial.puts("\r\nClock wrap-around\r\n");
               while(Time.read() < 1);
               t = 1;
            }
        
            if (t - tFlash > FLASH_DT)
            { // Flash standard LED to show things are running
                tFlash = t;
                DiagSerial.printf("dt=%d\r",t);
                toggleFlash();
                //reportCurrent();
                //wait(0.8f);
            }
        }
    }
}