A compass that doesnt point north
Wayfinder began as an exercise to try and develop product ideas. I took a liking to it, as a neatly scoped and doable function and as an opportunity to refine my experience with PCB layout and embedded firmware. It uses a GPS and magnetometer to resolve a heading towards a coordinate, and then uses a ring of LEDs to indicate distance and direction as well as device status.
The initial prototype was simply a functional prototype, and was not intended to proof out any final hardware. I used components I had laying around, and then cobbled them into a functioning prototype that would resolve a good heading. After my first experiments with a non tilt compensated compass, I decided that an accelerometer would also be a required component.
In this first revision, I tried to segment the different subsystems of the Wayfinder, so that I could easily prove out individual subsystems. I included an onboard charge controller for a lipo battery, as well as power control circuitry for those subsytems to allow low power operation, a topic that I was interested in developing an understanding of and wanted to be able to implement. I used an off the shelf SMD GPS to avoid issues with antenna design and other topics of little interest to me. I used a standard Atmel chip, to be able to quickly test with an Arduino bootloader, and move to AVR-GCC when necessary.
For the next revision, I switched to using a smaller profile components in anticipation of getting the PCBs assembled, and a pogo pin connector and charger so that I could place the battery on the front of the PCB and keep the back flat. I custom programming cradle was a nice touch to enable testing and easy reflashing of the firmware. I made sure to switch to a set of standard components used by Seeed Studio, so that when they did assembly there would be minimal issues.
It took an embarrassingly large amount of time to assemble one of these boards by hand, and I was not interested in repeating the experience of assembling one. I had never had PCBA done, so I took this opportunity to get a run of five of these boards made. It went incredibly well, and only required me to solder on the GPS and LEDs myself, which Seeed Studio did not have in inventory. These boards worked perfectly when they arrived, and cost me much less time in assembly.
While they Wayfinder is not a great product due to the ubiquity of phones with precise GPS and mapping applications, it was a great personal experience. I loved starting with a high level design idea, prototyping it, formalizing it in layout, building a high level prototype and then taking it to production. The final device allows you to lock in a home position with an unambiguous input, and then it will always show your way home quickly and easily.