brtaylor
Well-known member
Overview:
I'm working on a Teensy 3.6 project where I would like to create an analog signal conditioning circuit that can be flexibly configured by the Teensy to work with a variety of input signals. I'm anticipating this circuit to need to work with:
1. Potentiometers
2. Strain bridges
3. Analog instruments (i.e. pressure transducers, accelerometers, gyros, etc)
It would be nice to also accommodate RTD temperature sensors; however, this can be on it's own circuit if needed.
Analog data will be sampled at a fixed 400 Hz rate, so I would use a 200 Hz AAF stage as part of my analog filtering. Other aspects of this project will make the per-unit costs high, so I'm not budget limited for this design.
Initial Thoughts:
I already know that I'll likely need several reference voltage sources available for the customer to use. The customer has typically used 10V reference sources for their POTs and strain bridges. Most analog instruments I see are looking for a 3.3V source. So, my current thought process is to make several sources available: something like 3.3V, 5V, 10V, higher? I know that I'll need an AA filter stage. My biggest question is how to attenuate the incoming voltage signals? I could use a voltage divider set to the largest reference voltage, follow it with a trim stage (using the Teensy's DAC and a summing amplifier), and then a PGA to bring the potentially tiny signal up to meet the full scale range of the Teensy ADC. Are there better approaches like programmable voltage dividers, below unity op amps, or digital POT's that I should be considering instead of a voltage divider?
I'm working on a Teensy 3.6 project where I would like to create an analog signal conditioning circuit that can be flexibly configured by the Teensy to work with a variety of input signals. I'm anticipating this circuit to need to work with:
1. Potentiometers
2. Strain bridges
3. Analog instruments (i.e. pressure transducers, accelerometers, gyros, etc)
It would be nice to also accommodate RTD temperature sensors; however, this can be on it's own circuit if needed.
Analog data will be sampled at a fixed 400 Hz rate, so I would use a 200 Hz AAF stage as part of my analog filtering. Other aspects of this project will make the per-unit costs high, so I'm not budget limited for this design.
Initial Thoughts:
I already know that I'll likely need several reference voltage sources available for the customer to use. The customer has typically used 10V reference sources for their POTs and strain bridges. Most analog instruments I see are looking for a 3.3V source. So, my current thought process is to make several sources available: something like 3.3V, 5V, 10V, higher? I know that I'll need an AA filter stage. My biggest question is how to attenuate the incoming voltage signals? I could use a voltage divider set to the largest reference voltage, follow it with a trim stage (using the Teensy's DAC and a summing amplifier), and then a PGA to bring the potentially tiny signal up to meet the full scale range of the Teensy ADC. Are there better approaches like programmable voltage dividers, below unity op amps, or digital POT's that I should be considering instead of a voltage divider?