This past weekend, I decided to try to produce a printed circuit board. I also wanted a challenge (plus I need to fit the circuit into a small space), so I started with a surface mount board, with really tiny components.
The circuit I started creating is a breakout board for the LY120 screen on the Grove 0.96″ OLED display. This is a great little screen with a resolution of 96×96 pixels, 16 bits of gray scale, and the controller chip supports I2C, SPI, and a 8 bit parallel communication. The breakout board it comes with only supports the I2C, but I want to try out all the communication possibilities to find the fastest one, hence why I need this new board.
I used KiCad to do all the circuit design and PCB layout. It is a really nice program, and it is all open source, so it can be used for commercial products without any kind of license! I was learning the program as I was going, so this step took awhile. The PCB routing is quite cool though; you place a trace, and new traces will push the old ones out of the way as you lay them so they all fit.
As I was designing the circuit and reading all the datasheets for the screen, I found that it needs about 13V for power and 2.5V for logic, I have 3.3V from a Lipo battery. I was hoping to not use most of the components on the original Grove board, but I ended up copying and stealing the components from the other board. It was a good way to learn, as they already had a 13V and 2.5V supply, although from a 5V source.
I have two 10 pin headers that I can plug into a solderless breadboard. They breakout all the communication pins, ground, 3.3V in, and the 12.8V and 2.5V out. The whole board is one sided because I didn’t want the added complexity of trying to align a double sided board off the bat. There are a couple spots where jumpers are needed, but I tried to limit those as much as possible.
The output of this processes is a negative of the circuit printed onto a transparency. I used my ink jet printer, which it says has up to 600dpi resolution for black and white images. I printed three copies of the negative, cut them out, and aligned them on top of each other. This helps make them darker for the next step, UV photo-lithography!