This project is an Arduino shield use to connect an Arduino to one or more TLC 5940 controllers using flatcable and my larsskj-001 boards.

PCB layout

The shield connects the TLC 5940 to the Arduino like this setup:


There's a few differences, though: If you use the shield without modification, power for the TLC board is connected to the DC plug on the Arduino. This means that the TLC will get power through the flatcable if an external PSU is connected to the Arduino. If, on the other hand, the Arduino is powered from USB and a computer, the TLC board will not get powered at all. You can connect power to the TLC board using my larsskj-001 board in this situation.

I learnt this the hard way: My earlier attempts connected VCC on the TLC to the 5V supply on the Arduino, meaning that the TLC would get power even when the Arduino gets power from the USB. Having connected about 10 LEDs this way, my computer suddenly popped up a message box telling that I drew much too much current from the USB - a few seconds later the USB port broke down and never worked again. We had to replace the motherboard in the laptop - that's rather expensive.

Because of this experience, I've chosen to connect the TLC to the external PSU connection only. If you know what you're doing, you can change this: Cut the connection at JP1, close the connection at JP2, and the TLC will get connected to the 5V supply on the Arduino the dangerous way. If you prefer not to draw current from the Arduino at all, you can cut the connection at JP1 and leave both "jumpers" open.