Sergio Fernandez Santos

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9 years, 4 months ago.

Using digital pins as multiplexer for PGA

Hi, I want to build a PGA. To control the gian im planing to use an op amp in non inverter configuration. I want as in the figure:

https://upload.wikimedia.org/wikipedia/commons/thumb/6/66/Operational_amplifier_noninverting.svg/220px-Operational_amplifier_noninverting.svg.png

I want to know if I can use digital pins to multiplex resistors in order to modify the pin. I mean, 8 Rg resistors in paralel each one conected to a digital pin. I will have 7 pins as digital out (for high impedance) and one in digital out low to be grounded. I want to know if this configuration can be problematic. The signal to amplify is ac tanking positive and negative values so I wil have positive and negative values on my digital pins.

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