I just got video working over TWI / I2C on my Peggy 2.2 w/ATMega328. My Arduino is a Duemilanove, also with ATMega328.

I programmed both the peggy and the Arduino through the Arduino software, and after running into a hitch here and there, I thought it might be nice for others to have a simpler explanation all in one place. I also had to make a minor code modification to both the Arduino and the Peggy programs to get it working properly (commenting out a line, see 5 below).

1. Check out the EMSL Video Peggy Article and Jay Clegg's original "Video Peggy using TWI" page.

2. Download the Arduino and Peggy Programs. There are links to everything you need on the above two pages.
- 'Serial2TWIPeggy.pde' is the Arduino Program. It's available in the zip file at the bottom of Jay Clegg's project page.
- 'Peggy2Recv_TWI.pde' is the Peggy Program. Jay Clegg's zip file does include instructions for creating this program, but EMSL has the pde file ready for download at the bottom of the article.

3. Download the 'Processing' software and the Peggy conversion sketch. This will read in from your webcam, convert to 25x25 resolution, and send to the Arduino over Serial. These two files are linked from the EMSL article.

4. Solder up three leads to your Peggy for the I2C connection: to ground, to SDA, and to SCL. These leads will plug into the Arduino's Ground, Analog 4, and Analog 5 pins, respectively. However, I found that SDA and SCL should NOT be plugged into the arduino until the programs were uploaded to both boards.

5. Modify the programs:
- You need to point the Processing sketch 'MirrorPeggy.pde' to your Arduino's serial port. Open up the file in Processing and change this line of code to reflect the correct port:

- I got some errors trying to compile both the Arduino and Peggy programs due to this line of code:

The error prevented Arduino from compiling. I commented out the line, and after that everything was peachy.

6. Load up the programs: 'Peggy2Recv_TWI.pde' goes to the Peggy, and 'Serial2TWIPeggy.pde' goes to the Arduino.

7. Plug in SDA and SCL to Arduino's Analog 4 and Analog 5.

8. Run 'PeggyMirror.pde' in Processing. If all goes well, you're now playing video from your Webcam to the Peggy! I had to reset my PRAM when my MBP decided it didn't want to use it's iSight, but I believe that's an unrelated Mac software issue.


Can anyone out there enlighten me as to what the "PORTC |= ..." code is supposed to be doing, and why I needed to comment it out?

I'd like to add: for someone with no PCB experience, my Peggy assembled very easily and has worked flawlessly since I added the jumper wire across L2 per Windell's instruction update.

>PORTC |= (1<<PC5) | (1<<PC4);

The "PB" and "PC" abbreviations changed in the underlying code for the ATmega168 versus ATMega328P, quite unnecessarily. Probably will work fine if you replace this with: PORTC |= (1<<5) | (1<<4);

* Some hints for windows users:

'Original' code:

peggyPort = new Serial(this, "/dev/cu.usbserial-FTE0T5YQ", 115200); // CHANGE_HERE

Should be something like this:

peggyPort = new Serial(this, "COM5", 115200); // CHANGE_HERE


* WinVDIG can be found here:
http://www.eden.net.nz/7/20071008/

* I had an issue to make the camera work ( Problem connecting Video Output to Video Renderer ), this is where I found the answer (deleting some files and downgrading WinVDIG):
http://processing.org/discourse/yabb2/YaBB.pl?num=1159144149/0

Hope this is useful.