File content as of revision 4:50879dfb82d5:

#include "mbed.h"
#include "TextLCD.h"
//mbed DCC Model Train Demo
 
DigitalOut Track(p20); //Digital output bit used to drive track power via H-bridge
DigitalOut led1(LED1);
DigitalOut led2(LED2);
DigitalOut led3(LED3);
DigitalOut redled(p29);
DigitalOut greenled(p30);
DigitalIn switch1(p9);
TextLCD lcd(p22,p21,p23,p24,p25,p26);
AnalogIn pot(p19);
DigitalIn d21(p13);
DigitalIn d22(p14);
DigitalIn d23(p15);
 
void DCC_send_command(unsigned int address, unsigned int inst, unsigned int repeat_count)
{
    unsigned __int64 command = 0x0000000000000000; // __int64 is the 64-bit integer type
    unsigned __int64 temp_command = 0x0000000000000000;
    unsigned __int64 prefix = 0x3FFF; // 14 "1" bits needed at start
    unsigned int error = 0x00; //error byte
    //calculate error detection byte with xor
    error = address ^ inst;
    //combine packet bits in basic DCC format
    command = (prefix<<28)|(address<<19)|(inst<<10)|((error)<<1)|0x01;
    //printf("\n\r %llx \n\r",command);
    int i=0;
//repeat DCC command lots of times
    while(i < repeat_count) {
        temp_command = command;
//loops through packet bits encoding and sending out digital pulses for a DCC command
        for (int j=0; j<64; j++) {
            if((temp_command&0x8000000000000000)==0) { //test packet bit
                //send data for a "0" bit
                Track=0;
                wait_us(100);
                Track=1;
                wait_us(100);
                //printf("0011");
            } else {
                //send data for a "1"bit
                Track=0;
                wait_us(58);
                Track=1;
                wait_us(58);
                //printf("01");
            }
            // next bit in packet
            temp_command = temp_command<<1;
        }
        i++;
    }
}
//DCC train demo turns on headlight, dims headlight, and moves back and forth at half speed forever
int main()
{
    led1 = 1;
    wait(0.5);
    led1 = 0;
    wait(0.5);
    led1 = 1;
    //typical out of box default engine DCC address is 3 (at least for Bachmann trains)
    //Note: A DCC controller can reprogram the address whenever needed
    unsigned int DCCaddress = 0x01;
    //see http://www.nmra.org/standards/DCC/standards_rps/RP-921%202006%20Aug%2021.pdf
    //01DCSSSS for speed, D is direction (fwd=1 and rev=0), C is speed(SSSSC) LSB
    unsigned int DCCinst_forward = 0x68; //forward half speed
    unsigned int DCCinst_reverse = 0x48; //reverse half speed
    unsigned int DCCinst_stop = 0x50;
    //100DDDDD for basic headlight functions
    unsigned int DCC_func_lighton = 0x90; //F0 turns on headlight function
    unsigned int DCC_func_dimlight = 0x91; //F0 + F1 dims headlight
    //
    //Basic DCC Demo Commands
    DCC_send_command(DCCaddress,DCC_func_lighton,200); // turn light on full
    DCC_send_command(DCCaddress,DCC_func_dimlight,200); //dim light
    DCC_send_command(DCCaddress,DCC_func_lighton,200);  //light full again
    led2 = 1;
    while(1) {
        
        
        
        if(d21 == 1 || d22 == 1 || d23 == 1){
            lcd.cls();
            lcd.printf("Choo Choo station");
            DCC_send_command(DCCaddress,DCCinst_stop,400); // forward half speed train address 3 
            
        }else{
            DCC_send_command(DCCaddress,DCCinst_forward,1); // forward half speed train address 3 
        }
        
        
        /*
        float f = pot.read();
        float vin = f * 3.3;
            
        led3 = 1;
        if(switch1 == 1){
            lcd.cls();
            lcd.printf("Going forward");
            greenled = 0;
            redled = 1;  
            DCC_send_command(DCCaddress,DCCinst_forward,400); // forward half speed train address 3 
            lcd.cls();
            
            lcd.printf("vin: %.4f",vin);
            wait(0.2);
            
        }else{
            lcd.cls();
            lcd.printf("Going backwards");
            greenled = 1;
            redled = 0; 
            DCC_send_command(DCCaddress,DCCinst_reverse,400); // reverse half speed train address 3
            lcd.cls();
            
            lcd.printf("vin: %.4f",vin);
            wait(0.2);
            
        }
        */
    }
}