Read analog low-pass filter to Arduino

Thread Starter

Aresvy

Joined Feb 2, 2018
11
hi,
Could you post an image.?
What is the sampling rate of the ADC.?
E
This clamping circuit image is another ADC protection input, should protect the ADC from most failures of the OPA.
Hi,
I now understand that the arduino Uno can't plot negative voltage thanks to a partner, so the graph i was seeing was in fact correct.
 

ericgibbs

Joined Jan 29, 2010
9,562
hi Aresvy,
A +5v step input to your circuit will not generate a negative voltage swing at the output, ie: ADC input
The Vout response plot will always be above 0V.
Why do you think a negative voltage swing is going to occur.?
E
 

Thread Starter

Aresvy

Joined Feb 2, 2018
11
hi Aresvy,
A +5v step input to your circuit will not generate a negative voltage swing at the output, ie: ADC input
The Vout response plot will always be above 0V.
Why do you think a negative voltage swing is going to occur.?
E
It was a mistake from my part, sorry about that.
 

ericgibbs

Joined Jan 29, 2010
9,562
hi,
Looking at your Excel plot, I would guess you have the ADC input connected.?
The MCU clamp diode is limiting the below zero voltage swing.

If so I would recommend you add a series resistor from the OPA output to the ADC pin, in order to limit the clamping current.
Say, 470R or 1K
E
 

swn12

Joined Sep 29, 2015
1
Hello Folks. I used an Arduino Uno before, and specifically the Analog.Read() function. I know for a fact, and according to documentation from Arduino forum, that the sampling frequency is 10kHz.
 
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