When was the last time you did something for the first time? For me that is: just now. I am quite excited to have ordered my first ever custom PCB.
Some time ago I read about the Texas Instruments TLC5940 LED driver IC. It features 16 channels of PWM control with a 12-bit resolution, which means you can control 16 LED’s per chip and dim each LED form off to fully lit in 4096 steps. Or, you could use those channels to control RGB LED’s in which case you could address 5 RGB LED’s per IC and have one channel to spare. In addition to this, it is quite easy to daisy-chain multiple TLC5940’s together.
I ordered a sample from TI to experiment with in combination with an Arduino Uno and with the help of the Arduino Playground I found out how to hook them up and a library to easily address each channel. And before I knew it I was able to get some example code running:
This was exciting! However, doing knight-rider style light-effects on a breadboard is only going to entertain for so long. I have a bunch of (200+) white 5mm LED’s laying around here, which cannot be easily fitted to the breadboard in large quantities, so I decided to finally take the plunge and try to come up with a custom PCB to make a modular PCB that contains one TLC5940 and 16 LED’s and connectors to string multiple units together. And with the help of two great tutorials by SparkFun (“Beginning embedded electronics 8: Eagle Schematics” and “Beginning embedded electronics 9: Eagle PCB Layout“), I designed this schematic and PCB:
I had them looked at by an electronics guy at work, who did not see any obvious issues with it, so I decided to order 10 of these from MakePCB.com today. From what I have heard their communication skills are below par, but the PCB’s are of good quality and the costs were lowest I could find with shipping to my address. Now the long wait begins!
Just to be clear: I do not have a background in electrical engineering, I am test engineer by trade. I did not know *anything* about pcb’s apart from what they look like in a device before I started this and regardless of if the PCB’s are completely correct or not: I was able to pick up all this knowledge online and practice with free and often open-source software, making this a very low barrier to entry.
As soon as I have those PCB’s I will solder the components to it, and maybe fix an error here or there, but hopefully show a great result! And of course, once the design has proven to be correct and functional, I will share them here with you!
To Be Continued…