Some time ago I bought another 3D printer, this time one that uses resin to print. However after printing the parts are not full strength yet. To solve this the parts need to be put in UV light. This can be done outside in the sun or in an UV curing device. Since the sun does not always shine when I’m printing I decided I need a UV curing device.
I did some research on this, but only saw devices that where either much too expensive, or the quality too low or very unpractical. At this time I was thinking why not convert an old microwave oven. It has a rotating disk to put the prints on, it has a timer and it is nice and enclosed.
After asking around I got a defective microwave oven. The tube was defect. However this does not matter for my use-case since I replaced the MOT and tube with a LED driver and UV LEDs.
Now in theory it should already work, but I wanted to make it more custom. I saw that the driver board contained an old PIC16C65B microcontroller. This is a one time programmable, so I replaced it with an (also old) PIC16F877A. Now the timer can be equipped with custom firmware.
Only now the difficult part started. The pins that go to the 7 segment displays do not only drive the displays, they also read out the switches. This took a lot of searching and reverse engineering of the circuit board. I do not have a full schematic off it since I only did what was needed. But I did make a sketch to make this more clear:
The code I wrote for the microcontroller: