I’m starting to roll up my sleeves for my third attempt at building an ocean sport fitness tracker. I paddle surfskis, which are long and narrow sit-on-top kayaks designed to surf waves in the open ocean. It’s a very addictive sport because it engages the whole body paddling and balancing as well as the brain to read waves and figure out where to steer towards
I want a tracker that does two things: measure my performance (speed, heart rate, stroke rate) as well as send my position to my spouse in case there’s a problem so I can be located.
My first attempt 2 years ago looked like this:
It included an STM32L082 board I designed with a HopeRF LoRa radio, a GPS breakout board, and an IMU breakout. I also jammed a BLE breakout in there to connect to a heart rate strap.
I learned that I really need to spend the time to integrate things tightly so the total package size actually fits on the foot strap. That I need to select my components better, e.g. the GlobalTop GPS works and is cheap but if you really want 10Hz position reports with good accuracy to measure acceleration on a wave, say, then steer towards u-blox. And I need to think more carefully about the communication, and antenna design in particular (I expected it not to work well, but didn’t have much choice).
Some “fun” moments included me falling out of the surfski and opening the latch of the waterproof box with my toes. I found the electronics and battery floating in the surfski. After a slew of cleaning, a new battery and some reflowing of the gps module everything worked again! Second “fun” moment was forgetting the box in the surfski on the roof rack and loosing it enroute .