A Very Annoying Business Card

After removing the replacing the MCU, a short to pin 4 was cured and selecting the correct board in Arduino cured the pin definition problem. Turns out the MCU was fine, but the short must have been underneath it.

Now it is sitting on a sunny shelve happily beeping every 2 hours and 17 minutes. Only problem now is that it does not seem annoying to me - I actually quite like it! I guess it would be annoying if somebody was trying to sleep though.

Finally got 'round to populating the business cards and fixing a few errors. I missed a few grounds on the logic gates, which was no big deal to fix, and found that the SEEED Xio SAMD21 MCU could not drive the buzzer directly and so had to switch in a ZTX 450  NPN transistor, which worked ok. Although the circuits 'kind of' worked, it seems that I have damaged the MCU, which is a bit annoying (pun intended)  probably trying to drive the buzzer, so that needs to be swapped out for a new one. Strangely, the buzzer still works although pin D1 now thinks it's D2, which is very strange. Pin 13 also works, powering the onboard LED, but none of the other pins seem to work. Hopefully easy to fix once the MCUs arrive from Digikey. Plenty of time before the competition finishes although fairly sure it's not going to win anything :(

After a bit of friendly haggling over the number of business cards to be produced, Liam from PCBWay agreed to fully sponsor this project with some lovely gold ENIG plated pads, solder pasting stencil and perfectly reproduced artwork and email address font. I was worried about the font, but it seems most people have Verdana somewhere on their computer systems. It would be pretty bad if the address was in system font or some over strange offering.

All of the circuits have already been tested so it should be just a case of placing the components and throwing into the reflow oven. A few changes to the design had to be made including getting rid of the ESP32 C3 board as it seemed to be a fake and replacing it with a fully branded and trusted Seeed Studio Xiao ESP32C3 Tiny MCU, which worked fine.

One noticeable choice in the design is the battery holder. It's an expensive component, but in my mind very worthwhile. The worst thing I could do is fly all the way to the Bahamas to visit the prospective billionaire project investor with a business card that has a loose battery. With this battery holder, you literally have to prize the battery out with a screwdriver - it will never accidentally fall out or come loose!

Basic initial layout looks ok. Main thing is that the battery fits inside the rat's abdomen. The timer module is just copy and pasted from another project so that should be fine. Just waiting to test a suitable IMU, which should arrive Monday-ish. Could be room for more than one buzzer, which could be fun.

The layout has to make sure that the battery does not interfere with the artwork. Fortunately, it fits nicely in the rat's stomach !!