Some reliability problems with my DS3231…

I was working on some additional software to power my nascent WSPR project. I’ve been thinking that rather than using an Arduino, it would be better to use the Teensy, so I’ve been experimenting a lot with the Teensy LC. My idea was to wire up my Ultimate GPS and an I2C based DS3231, and then write a sketch that powers up the GPS, attains a fix, and then uses the time to set the time on the DS3231. It then will periodically wake up the GPS and check the time as reported by the DS3231 against the GPS.

But I’m having some difficulty. The GPS part works just fine, but when I try to do the first write to the DS3231 to set the time, it occasionally hangs. The way these libraries are written, the writes never time out, and the exchange grinds to a halt.

I’m not sure what’s going on here. Could be a bug/issue in the library, or something having to do with the Teensy Wire library, or the pull-ups. The rise times seem very slow.

I’ll keep playing around to figure out what the deal is.

Addendum: This seems relevent but the code is only for real Arduinos, and probably needs some tweaks to work with the Teensy. I am curious as to whether the delay itself may be enough to help.