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The BOM indicates that the clock oscillator is just a vanilla quartz crystal. http://www.ti.com/lit/df/swrr135b/swrr135b.pdf Does the firmware do any clever temperature compensation using the onboard thermometer, or are you just sending lots of clock skew correction packets as the mesh warms up and cools down diurnally?

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For this level of time synchronization it is enough to send a few extra bytes with synchronization information in each packet. If you'd be down at microsecond-level synchronization, you probably need to do temperature compensation - particularly in outdoor deployments where there can be a 40 C / 100 F difference between two nodes on a sunny winter day.

Yeah it's just a regular XO. There's some calibration data they stick in a special flash area at the factory that the radio firmware uses to handle temperature compensation for the chip's internal digital oscillator. I also believe you can run it in a XO-less mode with some caveats.

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