Rainbowduino issues

Ok...I have been searching the far corners of the internet to find a project using a rainbowduino and common cathode RGB led's...I know the rainbowduino uses a constant current sink LED driver...

I am trying to figure how I need to wire the LED's off of the rainbowduino's red, green and blue pins in order to create my own 4x4 or 8x8 matrix. I am a bit confused on how to create my own grid...
Also, since I only have common Cathode RGB LED's, what do I need to change to make this work? Any help would be greatly appreciated!

The rainbowduino has 8 outputs to source current and 24 current controlled inputs as sinks. This requires common anode leds.

For common cathode leds, you'd need 24 current controlled outputs as sources and 8 inputs to sink current. Plus changing all of the low level code of course.

The easy way out is to get common anode leds and keep the others for future projects. Or sell them on ebay. Unless you want to do a complete redesign of the rainbowduino with parts you're not likely to get (current controlled source drivers)...

Thanks for the reply...I was afraid of that...and I have three TLC5940's on the way and it looks like I won't be able to use these LED's with those either. Time to buy some new LED's. On another note, has anyone ever had any issues flashing the rainbowduino with an Arduino?

I am currently using An Arduino UNO (Arduino 0021) and have it connected according to the following diagram

but whenever I try and upload anything it comes back with this error...
"avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51"

If I disconnect the TX-TX & RX-RX connection between the two devices, it goes through just fine...but that obviously doesn't help since there is no longer a connection between them.

I bet it works if you pop out the chip.

Right now you have both chips wired up in parallel. I guess there is some interference.

Figure out how to flash the Rainbowduino...hopefully this will help other folks who may be having the same issue...

Using an Arduino Uno I did like you suggested and carefully removed the chip from the arduino board. I then connected the two boards in the following manner...

Rainbowduino I2C Bus -- Arduino

I2C Data (SDA) -- Arduino Analog Pin 1
I2C Clock (SCL) -- Arduino Analog Pin 0
TXD -- Arduino TX, Digital 1
RXD -- Arduino RX Digital 0
DTR -- Reset

After cable the two units together, open the Arduino IDE and select the "Arduino, Duemilanove, or Nano w/ ATmega328" board.

You should now be able to flash the rainbowduino with a new firmware.

Thanks to the guys at the following link as well as Madworm for the help.

I'm not sure if this will help, since I don't have a mega, but did you try uploading an empty sketch to the mega?

void setup() {}
void loop() {}

This is supposed to help on the 328-based boards. Personally, I just run my Duemilanove with the ATmega removed.