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[cmosfreak]

Hi Tom,

some time ago you mentioned the poor accuracy of the ceramic resonator as time base of the Arduino Atmega2560 board to be more than 1000ppm. Would it be possible to calibrate the board by using a RTC device, e. g. the DS3231 from Maxim? I think this would help all DIY builders among us who are missing the excellent stability of 10ppm of your original AstroEQ board!?

Andreas

[paul_astrix]

Andreas,

That is one idea, but requires significant software modification to ignore local timing and read from an RTC. Although reading the RTC will skew timing also. GPS calibration every 10-30 minutes might help; but for precision astrophotography accuracy everybody does guiding don't they?

I bought a 10ppm crystal from Farnell for £0.40 along with all the other components. It might be possible to replace the resonatorq with a crystal 100x more accurate, but read here first:

https://forum.arduino.cc/index.php?topic=379555.0

http://forum.arduino.cc/index.php?topic=160625.0

https://arduino.stackexchange.com/questions/16086/why-are-there-3-crystals-on-the-mega2560-schematic

You will need significant electronic skill to work on tiny SMD boards.

It might be easier to buy or build an AstroEQ!

regards
Paul