As part of the Battery Charger project I need a basic PIC dev board. I built one a long time ago for A2 coursework, and I even found the artwork lying around, but the tracks and pads were too small for hand etching and drilling. Trying to open the cad files in KiCad I discovered that they’ve changed everything, and half the symbols ‘cannot be found’. I’ve also completely forgotten how to use KiCad or schematic capture/Pcb design software in general: all pointing to a need to redraw.
After rather too long I proudly examined the result:
It’s incredibly basic: just a few headers, crystal, usb, and a few resistors and capacitors. The wiggle in that track is to balance up the differential length; it’s completely pointless at this scale but I quite liked it. If you look closely at the schematic you can see what I didn’t: the D+ and D- are wired to the wrong pins. If you look even harder you’ll notice that not-MCLR is tied to ground not VCC, so the MPU won’t even run. I didn’t notice that; more frustration.
The Pcb was made the usual way: print to photo paper from a laser, clean board with wire wool and ethanol, iron on, soak paper, scrub off with scourer, etch, clean. Google ’toner transfer pcb’ and you can find a lot of people who know a lot about it. I half-remembered, but it worked fine:
Does anyone know the concentration of ferric cholride for etching? I’ve lost the scrap of paper I used to keep pinned to the board with it written on, and it seems no-one thinks of niceties like that online… in the end I took a ratio, which was too dilute. But it etched in the end. Then to assemble, and mount on a bit of ply with an lcd module, regulator, and a scrap of pcb to develop on:
Program:
…and test. Of course, it didn’t work, because of those two idiotic mistakes.
Moving the resistor was easy, moving the usb lines more annoying:
Plug in the programmer, download the Pinguino bootloader (only available from a GitHub repository!), plug the usb into the computer and ’lsusb’: it shows up! Artwork and files will go up on my Gitlab repository when I have re-drawn.