Tuesday, 16 April 2013

UV exposure box controller

We found an old 16x2 character LCD display knocking around from a previous project which already had a 16-way 0.1" pin header soldered to it. It seemed a shame to mess it up so we left the pin header in place and  hacked an IDE ribbon cable to fit it. A two-row IDE connector simply connects each pin on a single row to alternate strands on the ribbon:

(since we're using a 4-bit interface we chopped a couple of strands back as they are not needed)

We've gone a bit off-plan with this board, making stuff up and dropping it onto the board, off-the cuff. Sometimes that means just tacking a few extra wires onto some pins (although mostly we end up doing that because we've not left enough power/ground pads to connect to!) and in this case, we've decide to add in a speaker (audible buzzer when time is up) and left wires trailing to connect our buttons and menu selector pot. The contrast for the LCD screen is controlled by the trimmer pot on the right - once it's set, we'll probably just leave it at that (maybe we could have even just created a simple voltage divider for contrast?)

In fact, it looks like our hardware is pretty much assembled and just needs a PIC and some firmware in there to get it working. Assuming it all works of course....