WARNING: this article is technical!
This week the assembled PCB’s for the prototype finally came in! Most chips, LEDs, resistors and capacitors are already soldered on by the factory so that saves me a lot of work. The only things that I need to solder myself are the microcontroller (atmega32u4), the crystal (that dictates the speed of the microcontroller), the USB-connector, push buttons and the potentiometers (for the faders and knobs).
After soldering the microcontroller and USB-connector, I wanted to give it a test ride. As per usual, it of course didn’t work immediately. When I connected the programmer to the ICSP header, absolutely nothing happened.
I tried everything but the microcontroller stayed non responsive. After hours of frustration, googling, measuring every connection possible and a good night of sleep, I decided to check the BOM (bill of materials that holds all components). There was the culprit: a number of components were ordered in the wrong value (a lesson in triple checking everything).
So they needed to be replaced. The original SMD components are super small so while easy to remove, they’re quite hard to replace. Luckily I have loads of (larger) through hole components laying around.
The result is looking rather fabulous ;):
Of course, this will be fixed in the final product.
First test ride
So when I soldered on the large resistors and capacitors and got things working, I decided to upload a program to test the LEDs. The KNTRL9 has 9 RGB LEDs on board that are connected in series. These are the same LEDs as you may know from LED strips that you might have seen in clubs or at someone’s home.
I created a simple program that just lights every LED in a certain color. Looks like they are all working!