A USB-flash sized GSM/GPS tracker with a wide array of features
I have started working on the bootloader and testing a couple basic sketches.
So far, all routing and signals seem to be OK. Power (5V from USB) is not shorting anywhere and it seems that it should be safe to start working on programming the MCU.
All parts have finally come together and I was able to complete the first prototype. Everything came together very nicely and the height of parts and PCBs is exactly as I planned, which is very rewarding considering all challenges, especially since some parts weren't available earlier ans I had to depend only on datasheets for sizes and footprints.
Now to make sure all signals are correct and then I can do some test programming
The most challenging aspect of this project was fitting all parts into a very confined space. I chose a readily available ABS plastic enclosure designed for USB sticks. The available board space inside was meant for one PCB only, but two sides of one PCB weren't enough for all of the components. I knew I had to find a way to stack two PCBs inside.
After thoroughly measuring the available inner dimensions, I knew it could be done, but all components would have to be 2mm or less in height. Digging through many parts catalogs and with inspiration from smartphone board design, I was able to find the board-to-board connectors and the most important part - a micro-SD and nano-SIM two-in-one card holder.
Due to the constraints, some components are slightly more expensive than their bulkier counterparts, but no compromises could be made. I am extremely happy with the final design of the boards.