I moved to using a M0 in an Trinkey, well the chip is blazing fast, but it lacks EEPROM. So back to the drawing board…
This is a fork of another idea of mine here, but I decided to move away from the incrementing counter, and realized the time can come from a NIST broadcast for North America. The keyboard wedge can remain platform agnostic as a dumb keyboard, but still provide the current time to generate a TOTP code.
The WWVB receiver is big, and could never go in an implant. It also supports receiving time from other authorities MSF (UK) and JJY60 (Japan)
Assuming you have a good antenna and not a lot of EMI. I bought some WWVB clocks and my 2nd story “lab” has too much electrical noise to get the clocks to set. And I’m only a state away from the station. I ended up using a PiZero and a project that actually puts out the WWVB signal on one of the IO pins. Put a wire loop on it and the clocks would pick up the signal. I then found out the crappy clocks only set when you press the button instead of once a day… and they run about a minute a month fast!
A minute fast or slow is sometimes acceptable for OTP. (It has a 30 second resolution) But excellent feedback, I might have to put in an RTC board and lipo battery inside to preserve the time it can get when it does get it.
I live out on the plains of Colorado, so I should have a phenomenal signal for the Boulder, CO transmitter.
