File content as of revision 21:31647d80614f:

#include "mbed.h"
#include "TextLCD.h"
#include <string>
#include <iostream>
#include "mcp23017.h"  


//board 1

I2C i2c(p28, p27);              // sda, scl pins (you can also use the other I2C port pins: 9,10)

const int addr0 = 0x20 << 1;    // 7-bit base address of the MCP23017 + address bits (which are 000 for the first one), shifted 1 place to the right (see top header)

DigitalOut myled(LED1);     //
DigitalOut myled2(LED2);    // led
DigitalOut myled3(LED3);    //
DigitalOut myled4(LED4);    //
AnalogIn Ain(p20);          // pot. met.

DigitalOut Track(p21);

DigitalIn sw1(p5);      // 
DigitalIn sw2(p30);     //   switches
DigitalIn sw3(p29);     //  
DigitalIn sw4(p28);     // 

void mcpWriteReg(uint8_t address, uint8_t reg, uint8_t data);   // Write an I2C register
uint8_t mcpReadReg(uint8_t address, uint8_t reg);               // Read an I2C register
void initMcp0(void);  

unsigned int DarkRedtrain = 0x01;
unsigned int DCCinst_forward = 0x68; //forward half speed

//move forward

//speed dial

//stop 

//read switch out

//read signal

//display message

//send command
void DCC_send_command(unsigned int address, unsigned int inst, unsigned int repeat_count);

TextLCD lcd(p22, p21, p23, p24, p25, p26); // lcd

int main() {
    while(1){
        unsigned int DCCaddress = 0x03;
        DCC_send_command(DCCaddress,DCCinst_forward,400); // forward half speed train address 3
        float f = Ain.read(); //Read voltage value
        float Vin = f *3.3;
        lcd.printf("%.2f", Vin);
        lcd.printf("\n");
        //myled=1; 
    }
}

void mcpWriteReg(uint8_t address, uint8_t reg, uint8_t data){
    char cmd[2];cmd[0] = reg;
    cmd[1] = data;
    i2c.write(address, cmd, 2);   // Write 2 bytes to device on specified address
}

uint8_t mcpReadReg(uint8_t address, uint8_t reg){
    char cmd[1];
    cmd[0] = reg;
    i2c.write(address, cmd, 1);     // Write address
    i2c.read(address, cmd, 1);      // Read value (one byte)
    
    return cmd[0];                  // Return the read value
}

void initMcp0(void){
    mcpWriteReg(addr0, MCP_IODIRA, 0xff);     // All inputs
    mcpWriteReg(addr0, MCP_IODIRB, 0xff);     // All inputs
}

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++;
    }
}