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Projects, Designs, and Technical Stuff / Re: (Yet Another) DIY Multislope ADC
« Last post by Kleinstein on Today at 07:46:23 am »There is no need for a super stable clock. The point is jitter over a time frame of some 10 µs. The switches and an optional buffer to improve the isolation would add a few ps of jitter anyway. So a standard crystal oscillator should be good enough. The crystal directly at the RP2040 as for the RP-pico could have an issue with the internal state effecting the clock - I had this issue with the AVR and this caused quite some INL error (e.g. 10 ppm range). Chances are 12 MHz directly with no PLL could be fast enough for the ADC, though this would not allow to use the USB while using the ADC.