When I receive my board, should I attempt to replace the voltage input resistor in the divider to attain higher ADC voltages for the power chip? If so, what value? I think this question is equally addressed to all experts in this thread, not just @jdeglavina. Obviously, startup parameters would also need to be changed to accommodate the change.
The point about attenuating the voltage and then amplifying it has more to do with noise and interference than anything else.
If you (say) attenuate the voltage by a factor of 100 and then amplify it by a factor of 100, what it means is any noise or rubbish that gets onto the signal after the attenuator can be 100 times smaller to have the same effect as it getting onto the signal before the attenuator - or more to the point, getting onto the signal in the absence of both attenuator and amplifier.
If you need to up the voltage calibration by more than 65k, and you don’t want any of the output values scaled in software, then you can if you want to. With a 12VAC output AC Transformer you shouldn’t have to scale anything in software. You could change R14 & R18 to 51k 1/4W 1% 0604 resistors - like ROHM ESR03EZPF5102
Makes sense!
Alright, thanks. I’ll do the initial tests as I mentioned earlier and see how much work it is to change the resistors and the sw.
The resistors can easily be swapped with a hot air soldering gun. For the software, you would only have to calibrate the voltage again, and phase angle offset, if you want (this would be a change in the ATM90E32 library).
Why should I? Isn’t the resistor swap the equivalent of an amplitude gain adjustment?
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Sorry, I didn’t see that you posted this previously. Yes, swapping the resistors would allow more voltage in. I meant setting a phase angle offset in case your AC transformer introduces some error. You probably won’t need to do that though.
FYI, for the next revision, I’m going to use 20k 1/4W 1% resistors in place of the 100k. This gives an input voltage of about 520mV with a 12VAC transformer.
Thanks for the heads-up. I received my board a while ago but couldn’t get to test it because of work piling up. I’ll get back here when I can.
No se si me recuerdas, Te escribi hace un par de dias con una screenshot similar al tuyo en esta publicación con mis datos totalmente diferentes, podrias ayudarme con eso?
Just replied to your last email.