Getting the Sparkfun EL Escudo to work
Sunday, 15 April 2012
I’m really disappointed in Sparkfun. I recently purchased the EL Escudo shield for driving EL wire with a microcontroller, and woe be upon anybody who doesn’t do hours and hours of Internet research before plugging the thing in. There were 3 years of questions from poor customers with only a few answers, and the few answers that were there were often contradictory. Here are my conclusions from my Internet research, and the amazing Will Byrd helped me finally get it to work. Long story short, Sparkfun sets you up to fail and hasn’t fixed things in 3 years.
Buy everything you need
You’ll want stackable headers for Arduino: two 8-pin headers and one 6-pin header. You also need an inverter to provide high-voltage AC current. I ordered the 3v inverter that Sparkfun sells (COM-10201).
Don’t fry your inverter
Vin on the EL Escudo feeds straight into your inverter. If you got a 3v Inverter, and power it from your Arduino’s 9v barrel jack, you’ll fry your inverter. Do what I did, and clip the Vin pin and instead wire a jumper between +3.3V and Vin.
Fix the provided code
If you’re using Arduino, the provided code is not only too old for Arduino 1.0 to open, but it’s wrong. The original author uses
digitalWrite(channel, LOW) to turn on a wire, which not only doesn’t make sense, but doesn’t work (at least for me). I think HIGH and LOW might depend on how you’ve grounded your inverter output.
Luckily for us, somebody has embraced the Github way and updated the code for Arduino 1.0: https://github.com/pkrakow/EL-Escudo. Using that code, the provided blink program works, although I am still having trouble getting
all_off() to work.
Ground your inverter’s output if needed
If you’re using an inverter that has its own power, you might need to wire a lead from HVGND (the right Inverter Output pin) to GND. This is hearsay from the EL Escudo page, but you can simply check with a multimeter whether you need to do this or not.
Check that your inverter’s output pins are correct.
The two black wires in mine were swapped. Plugging in a strand of EL wire directly into my inverter would work, but I was getting something like 5V or 15V on EL wire jacks A through H instead of the 180V I should have been getting. Somebody else figured this out for the EL sequencer, but it wasn’t anywhere on the EL Escudo page.
Pull out the two black wires from the jack of your inverter and swap them if you’re getting the symptoms above.
Hopefully this helps somebody out there. If you still can’t get it to work, my advice would be to get a degree in Electrical Engineering.