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diminDDL / ProPico

An RP2040 dev board improving on aspects of the pi pico
http://ddl.red/propico
MIT License
223 stars 18 forks source link

Add support for precision XTAL/TCXO #3

Open mungewell opened 7 months ago

mungewell commented 7 months ago

For my own project, I needed a more accurate XTAL... obviously not everyone needs this, or wants to spend the extra money. However there is a nice 'hack'.

By adding 2 resistor footprints to connect to pin 2 of the XTAL, 'we' could configure the board to take either a passive XTAL or a (user performed modification) TCXO. Only extra one resistor, connecting to ground, would be fitted for mass production.

tcxo

Would you consider adding this?

More info on what I am doing. https://github.com/mungewell/pico-timecode/issues/4

diminDDL commented 7 months ago

While it looks interesting, there is some hustle associated with re-routing the board for this admittedly niche use case, I will leave the issue open and in case there will be more support/requests I'll consider it.

diminDDL commented 7 months ago

Upon further thought I think I might add it at some point in a similar way as described where it can be optionally populated as needed.

mungewell commented 7 months ago

Cool, thanks. I'm sure that there are others out there would also benefit.

I'm working on some automated testing, using uhubctl to cycle boards on/off and perform calibration process with my. This should help document variance between stock XTAL and TCXO...

mungewell commented 4 weeks ago

After being busy with other stuff this summer, I have restarted work on my Pico-Timecode project and have some test data showing how the stock XTAL is behaving. https://github.com/mungewell/pico-timecode/issues/4#issuecomment-2420900643

I appreciate not everyone needs this level of precision... My particular needs are sub-1PPM accuracy over varying temp, so a TCXO is probably a must.