I've got a Fitbit Charge HR wristband and I love it to bits, however I'm way too cheap to buy a Fitbit Aria WiFi scale so I decided to make one myself. I bought a BEEZ SM 1600B personal scale for the equivalent of ten bucks and I plan to "sniff" the communication between the board and the LED display. I'll use a 3.3V Arduino Pro Mini powered by a 18650 single cell LiPo and the most basc 433 MHz transmitter/receiver pair that I had laying around. The receiver will be connected to a WiFi enabled RaspberryPi.
My questions are the following:
- What kind of a performance hit will I get if i only power the transmitter with 3.3 volts? I need around 25 ft and one concrete wall worth of juice. I don't mind using an antenna.
- What kind of a "trigger" should I have to send the data? I don't want to log my flatmate's weight if he happens to step on the scale so it feels like I should have like a button and only that would send the data to the RPi. Otherwise it wouldn't get logged. Any ideas for better UX than a button on ground level?
I'll try to keep you guys updated with the project.