Connecting Arduino to iPhone/iPod serial

Success!

I've managed to get the Arduino and iPod communicating and can play/pause, skip forward and back, move forward and back through tacks and change the volume (iPod mode 2),

This is the code I'm using, a bit scruffy, sorry!

Code:

/*---------------------------------------------------
Controls an iPod through the dock connector's serial interface.
-----------------------------------------------------

Tx (output 1) ---[1k]-------------iPod pin13 Rx
   | -----iPod pin21 Accessory
   | |
   | |
   --- ---
   2k 1m
   --- ---
   | |
   | |
Gnd-------------------------------iPod pin11 Ground

   +5v
   |
   |
   ---
   2k2
   ---
   |
   |
analog inputs 0-4 --------------/switch/--- 0v

-----------------------------------------------------
v0.3 - Added switches code
-----------------------------------------------------
v0.2 - Added DEBUG mode
Added the DEBUG switch to be able to read the output without having an iPod connected.
-----------------------------------------------------
v0.1 - Initial code
iPod mode 2 (simple iPod remote) only.
-----------------------------------------------------
Resources used:

http://www.rosiedaniel.com/search/label/ipod

http://stud3.tuwien.ac.at/~e0026607/ipod_remote/ipod_ap.html
   http://instruct1.cit.cornell.edu/courses/ee476/FinalProjects/s2007/awr8_asl45/awr8_asl45/index.html
   http://ipodlinux.org/wiki/Apple_Accessory_Protocol
   http://pinouts.ru/Devices/ipod_pinout.shtml
-----------------------------------------------------
Mode 2 Commands
Command    |Purpose
-----------------------------------------------------
0x00 0x00 |Button Released
0x00 0x01 |Play
0x00 0x02 |Vol+
0x00 0x04 |Vol-
0x00 0x08 |Skip>
0x00 0x10 |Skip<
0x00 0x20 |Next Album
0x00 0x40 |Previous Album
0x00 0x80 |Stop
-----------------------------------------------------
*/

//Debug switch
//boolean DEBUG = true; //Send serial output in HEX with other formatting
boolean DEBUG = false; //Send serial output in BYTE for iPod connection

//Variables for the buttons
int buttonPins[] = {14, 15, 16, 17, 18}; //Array containing the pins the buttons are connected to
int numberOfButtons = 5; //The number of buttons connected
boolean buttonStates[]={false,false,false,false,false}; //Arrays for storing button information in
int buttonPresent[]={HIGH,HIGH,HIGH,HIGH,HIGH}; //Arrays for storing buttons states in
int buttonPrevious[]={HIGH,HIGH,HIGH,HIGH,HIGH}; // "
long time; //To keep track of the time for debouncing
int debounce = 200; //The debounce delay (from the last button push to the next)

//Define commands for iPod mode 2
byte switchMode2[] =    {0xFF, 0x55, 0x03, 0x00, 0x01, 0x02, 0xFA};
byte buttonRelease =    0x00;
byte PlayPause2 = 0x01;
byte VolUp2 = 0x02;
byte VolDown2 = 0x04;
byte SkipForward2 = 0x08;
byte SkipBack2 = 0x10;
byte NextAlbum2 = 0x20;
byte PreviousAlbum2 = 0x40;
byte Stop2 = 0x80;

void setup ()
{
  //Start the serial connection
  beginSerial(19200);

  //Setup the buttons
  for (int i=0; i<numberOfButtons; i++)
  {
   pinMode(buttonPins[i], INPUT);
  }

  //Switch to mode 2 (simple ipod remote mode)
  if (DEBUG){Serial.print("Mode 2: ");}
  for (int i = 0; i < 7; i++) {
   if (DEBUG)
   {
   Serial.print(switchMode2[i],HEX);
   Serial.print(" ");
   }else{
   Serial.print(switchMode2[i],BYTE);
   }
  }
  if (DEBUG){Serial.println();}
}

void loop ()
{
  //Loop through the amount of buttons
  for (int button=0; button<numberOfButtons; button++)
  {
   //Update the present state of the button
   buttonPresent[button] = digitalRead(buttonPins[button]);
   //If the button state has changed and the debounce duration has passed
   //The debounce period will work for all buttons. This means it will stop different buttons being pressed
   // within the debounce period but this shouldn't be too much of an issue.
   if (buttonPresent[button] != buttonPrevious[button] && millis() - time > debounce)
   {
   //If the button is pressed...
   if (buttonPresent[button] == LOW)
   {
   //Update the button's state in the array
   buttonStates[button] = true;
   if (DEBUG){Serial.print("Button: ");Serial.print(button);Serial.print(" Pressed ");}
   //Update the time the last button was pressed
   time = millis();
   //Depending on what buttons been pressed send a command
   switch (button)
   {
   case 0:
   sendCommand(VolDown2);
   break;
   case 1:
   sendCommand(VolUp2);
   break;
   case 2:
   sendCommand(SkipBack2);
   break;
   case 3:
   sendCommand(PlayPause2);
   break;
   case 4:
   sendCommand(SkipForward2);
   break;
   }
   //If the button is not pressed...
   }else{
   //Update the button's state in the array
   buttonStates[button] = false;
   if (DEBUG){Serial.print("Button: ");Serial.print(button);Serial.print(" Released ");}
   //Send the button release command
   sendCommand(buttonRelease);
   }
   //Update the button's previous state in the array
   buttonPrevious[button] = buttonPresent[button];
   }

  }
}

void sendCommand(byte cmd)
{
  //Create a checksum for the command
  byte cs = checkSum(0x03, 0x02, 0x00, cmd, 0x00);
  //Create a bytes to be sent array
  byte bytes[] = {0xFF, 0x55, 0x03, 0x02, 0x00, cmd, cs};
  if (DEBUG){Serial.print("Command: ");Serial.print(cmd, HEX);Serial.print(" ");}
  //Send the bytes
  for (int i = 0; i < 7; i++)
  {
   if (DEBUG)
   {
   Serial.print(bytes[i], HEX);
   Serial.print(" ");
   }else{
   Serial.print(bytes[i], BYTE);
   }
  }
  if (DEBUG){Serial.println("");}
}

int checkSum(byte len, byte mode, byte command1, byte command2, byte parameter)
{
  byte checksum = 0x100 - ((len + mode + command1 + command2 + parameter) & 0xFF);
  return checksum;
}

I've made some advances with Advanced iPod Remote mode (mode 4) as well but no luck in getting text returned as yet. There's also no volume control that I can find in mode 4 which would mean I'd need some more circuitry...

	Author	Topic: Connecting Arduino to iPhone/iPod serial (Read 7153 times)
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