This week was, for the most part, uneventful. Early in the week, I received the ADCs and a benchtop power supply to test/break them with. I have to say, I’m loving the MCP3021 library that I found. It has a built-in function to return the voltage of the ADC, and since I’m using it to monitor the battery, this is perfect. It also means that updating the code to include it involved only six lines of change.
After ensuring the device was working, I took it over to the power bench and found out how high I could take the ADC pin before releasing the Magic Smoke. Turns out, it’s a little over 18v, more than 3x the recommended operating voltage of the device. Plugging the device back in, it surprisingly still “Worked” – Although the ADC pin was fried, it would still generate spurious data occasionally. After soldering another ADC together to the testing board, I put the ADC pin on a constant 3.3v with the input voltage for the ADC disconnected. At that point, I left it on and went to do other things – Played a bit of Mass Effect: Andromeda, along with helping my father set up protection for some seedlings so the birds don’t tear them apart. About 8 hours later, I pulled the device from the power supply, tested it, and it still worked like a charm. So, thankfully, the ADC circuit doesn’t need to be modified to protect it.
In other news, I’ve decided to leave PCBWeb behind for future designs. Due to the amount of work I’ve put in to the V3, I’ll still be using it to finish off this design (And probably several revisions), but I’ll be teaching myself KiCad to replace it. Now, I’m sure you’re going to ask why, so here’s the answers:
First and foremost, PCBWeb lacks a number of features that are incredibly useful in designing PCBs. While it’s easy to learn and use, it lacks advanced things such as being able to cut holes into a circuit board like what is needed for the ribbon connector on the V3 screen (So the screen will sit flat), and its outline is either an all-angle design or a circle. There are no options for rounded corners, of all things! There are numerous other things which I’ve never needed, but I’m sure I’ll find useful.
Beyond that, and the direct impetus to switch, is that they switched from a DigiKey Library to an Arrow Library. Before I go much further, I’ll say that it’s not the library switch that irritated me, it’s how they did it. There was zero warning – I even searched their website, twitter, and Facebook for any hint of it and found nothing. Additionally, this update meant that the 250+ part library that I had hand crafted needed to be updated with Arrow part numbers. Manually. And when I went to pull DigiKey Part Numbers from them, they had all been removed. Now, the Manufacturer’s Part Number was still there, but in many cases DigiKey has multiple products for the same item – Different packaging options, along with things like buying the whole reel vs individually. It’s nice to know which one of those I had selected.
Hopefully, early next week I’ll be getting the first prototype boards of the V3 and will be able to assemble and test them. As always, feel free to join us on Discord, on Twitter, or on Facebook.