kevinreedy.net

I made a bunch of progress last week with my iPod project, but didn’t have the time to write up the details. Anyways, my parts came in the mail, so I headed over to noisebridge after work one day. I had two goals – get the serial communication working over the dock connector and get text on the LCD screen.

I wired up the dock connector in hopes that the previous code would just work. Fail. It turns out that my dock and ipodlinux.org conflict on what they call pin 1. Luckily, I found documentation on the Pin Outs. Once I soldered up the correct wires, the “Next every 3 seconds” script was working. I haven’t tested with anything other than my old iPod (see the video from last post). I remember reading somewhere that you need to put a resistor between a pin and ground to enable serial on newer iPods. So, I will have to take a look at that next time.

After that, I shifted my focus over to the LCD display. I was shocked how quickly I was able to get text on the screen. After wiring it up and copy and pasting some example code, I was successful. I have altered a bit to write out “Hello World” on letter at a time. Code and video below:

#include "LiquidCrystal.h" //include LiquidCrystal library

LiquidCrystal lcd = LiquidCrystal(); //create a LiquidCrystal object to control an LCD

void setup(void){
   lcd.init(); //initialize the LCD
}

void loop(void){
   lcd.clear(); //clear the display
   delay(250);
   lcd.print('H'); //send individual letters to the LCD
   delay(250);
   lcd.print('e');
   delay(250);
   lcd.print('l');
   delay(250);
   lcd.print('l');
   delay(250);
   lcd.print('o');
   delay(250);
   lcd.print(' ');
   delay(250);
   lcd.print('W');
   delay(250);
   lcd.print('o');
   delay(250);
   lcd.print('r');
   delay(250);
   lcd.print('l');
   delay(250);
   lcd.print('d');
   delay(1000);
}

The next step is to get advanced communication with the iPod working and being able to display the results on the LCD. So far, I was able to put the iPod into AIR mode, which enables advanced serial communications, but I haven’t tried to go any further.

I went over to noisebridge today to work on the iPod Project mentioned in the last post. I ended up making significant progress today! I am in need for a project name, as “Kevin’s Amazing iPod Hacking Project of Awesomeness” is a bit too long. Anyone have any suggestions?

The first thing I did today was get an LED to blink using the Arduino. It was pretty much a Hello World to get started. After that, I took apart an iTalk to salvage for parts. It connects to the serial port on the top of the older iPods (the remote connector next to the head phone jack).

Now that I had the piece to plug into the iPod, I soldered the appropriate wires to each pin. ipodlinux.org has a great diagram with the pinouts of the connector. I connected the pins on the connector to the Arduino: ground to ground, tx to rx, rx to tx. I didn’t bother with the power, as I am still powering the Arduino externally with USB.

Now that the hardware was all done, it was time to look at the software. Luckily, most of my work was already done for me by Rosie Daniel. I did some alteration/simplification for testing purposes. Instead of taking button inputs to control the iPod, I altered the code to send that “Next” command every 3 seconds. Forgive the code formatting until I figure out how to do this better with wordpress.

int buttonRelease[] = {0xFF, 0x55, 0x03, 0x02, 0x00, 0x00,0xFB};
int commands[]={0,0,0x01,0x08,0x10,0x02,0x04};

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

void setup() {
    Serial.begin(19200);
}

void loop() {
    delay(3000);
    sendCommand(commands[3]);
}

void sendCommand(int cmd) {
    int cs = checkSum(0x03, 0x02, 0x00, cmd, 0);
    Serial.println(cs,HEX);
    int bytes[] = {0xFF, 0x55, 0x03, 0x02, 0x00, cmd, cs};

    for (int i = 0; i < 8; i++) {
        Serial.print(bytes[i], BYTE);
    }

    for (int i = 0; i < 8; i++) {
        Serial.print(buttonRelease[i],BYTE);
    }
}

At first, I ran the code and nothing happened. I then noticed that my ground wire became unsoldered. I fixed that, tried again, and saw my iPod skipping songs every 3 seconds. Success! I have a video below, but please mind the bad quality. Although this write-up makes it look like I did all of this in a very short period of time, it did take me about 4 or 5 hours. Now that I have a successful prototype, I ordered some parts from SparkFun for the next couple of steps in the project.

• iPod Dock Breakout
• 16×2 Character LCD Display
• ATMega8 Microcontroller (I have heard of people having problems with the ATMega168, which I currently have)
• Some RGB LEDs