Hi Often when you dig into the details of MCU ADC’s they have a little note “optimized for audio” or “not recommended for control loops”. It can be a bit of a head scratcher to work out what they are getting at. The big issues in this case seem to be DC leakage and 1/F noise. Yes, they do sort of go hand in hand :) You need to be willing to check out the ENOB at DC in order to use them effectively in a simple OCXO setup. That or be willing to flip the bridge ends on demand and try to cancel out the issues. Unfortunately that adds both complexity and a string of other fun and games.
Op amps are cheap …. Bob > On Jun 6, 2017, at 3:54 PM, jimlux <[email protected]> wrote: > > On 6/6/17 11:47 AM, Chris Albertson wrote: >> Yes, as I wrote. I would not mess with AREF. At most you can only get a >> multiplication about 4. Use an op-amp. Signal conditioning really >> almost alway is required in the analog domain before any A/D conversion >> >> Also like the uP is not inside the oven and has a cable of some length so >> you'd want a buffered analog signal on the cable, the op-amp can do that >> to. >> >> Those $2 parts I linked to have the ADC referenced to 3.3 volts but have 12 >> bits as compared to the arduino which has 10 bits > > > or use a Teensy with a 16 bit differential input ADC. Arduino compatible, > cheaper, yeah, you probably get 13 bits real performance from the ADC. Also > has a real analog output (not PWM and a LPF) if you need that. > > Programmable gain, sample averaging in hardware, etc. Not bad for <$20. > > >> >> > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
