Advice on choosing components for basic control system

[fishyvishy]

Hello,

I'm looking to create a control system to try and hold a few DC signals at some defined setpoints. I'm looking for some advice on what microcontrollers, adcs and dacs I could use for this project. Since the signals are DC, I imagine I don't need a high sampling rate on the ADCs.

I see one option is to buy these components separately as in a build like this which uses an AD7734 ADC, AD5764 DAC and an Arduno Due, however the software would have to be updated to implement some control logic. Moreover, after talking with Analog Devices, the AD7734 seems pretty out of date and the resources on its eval board are a little sparse and the linked build does some fiddling with some jumper pins which I think I'd have to consult with Analog Devices about. They did recommend some newer ADC boards such as the AD7124, AD4130. One problem they mentioned is that their Eval Boards are meant to be used with their proprietary PC GUI and SDP controllers. I want to be able to use the system in scripts for experiments and such so this wouldn't be ideal. The AD4130 does come in an Arduino form factor which might make interfacing easier though.

Another option would be to use a dedicated DSP chip like something from the STM32F series which has lower bit depth but there would be less to worry about with the hardware.

I'm wondering if someone has done a project similar to this and has recommendations for components I could use.

Thanks

 

[Bluejets]

Reading any analog signal requires averaging to get a half decent signal which is why most will use digital sensors.

 

[Harald Kapp]

I'm wondering if someone has done a project similar to this

Your description is rather incomplete, so "similarity" to any other project is next to impossible to judge:
- Number of signals?
- Voltage range? Is it the same for input and output?
- Sampling rate? Or equivalently range of signal frequencies to be handled?
- Required accuracy?
- Duration of the hold time?
- What is that "control logic" you mention? Is this a simple sample-and-hold architecture or are the sampled signals treated algorithmically before the are output again?
- What are these "setpoints" you talk about? Points in time? Points within the voltage range? Points depending on the input signal (or a combination thereorf) or points depending on an external control signal?

I want to be able to use the system in scripts for experiments

What kind of scripts? Running locally on the hardware or running on a PC? What is the purpose of the scripts when your description starts with "a control system to try and hold a few DC signals at some defined setpoints"? No scripting required for this.

I'm looking to create a control system to try and hold a few DC signals at some defined setpoints.

Have you had a look into a simple sample-and-hold scheme instead of a complex A/D-µC-D/A scheme?

 

[fishyvishy]

Your description is rather incomplete, so "similarity" to any other project is next to impossible to judge:
- Number of signals?
- Voltage range? Is it the same for input and output?
- Sampling rate? Or equivalently range of signal frequencies to be handled?
- Required accuracy?
- Duration of the hold time
- What is that "control logic" you mention? Is this a simple sample-and-hold architecture or are the sampled signals treated algorithmically before the are output again?
- What are these "setpoints" you talk about? Points in time? Points within the voltage range? Points depending on the input signal (or a combination thereorf) or points depending on an external control signal?


What kind of scripts? Running locally on the hardware or running on a PC? What is the purpose of the scripts when your description starts with "a control system to try and hold a few DC signals at some defined setpoints"? No scripting required for this.


Have you had a look into a simple sample-and-hold scheme instead of a complex A/D-µC-D/A scheme?

Sorry for the lack of detail. Here's some more info
- 4 signals.
- 0-10V input and output
- DC signals to be handled
- Within 10mV.
- I am not sure about hold time duration
- Maybe PID?
- setpoints in the voltage range. We want to be able to update these setpoints from scripts running on a PC.

I haven't looked into sample-and-hold schemes. Thanks for pointing that out. I was also informed that this problem could be solved using analog ICs but our voltage references would still have to be digitally generated to update the voltage setpoints.

 

[Harald Kapp]

Maybe PID?

PID? PID is a control algorithm that takes an input signal and generates an output to a control mechanism such that the input signal will reach a defined value within well defined limits. That is far more than the sample and hold scheme you barely outlined.

- setpoints in the voltage range. We want to be able to update these setpoints from scripts running on a PC.

I still don't understand this point. Do you want to hold the input signal once it reaches such a "setpoint"? Or what else is the maning of "setpoint"?

It probably will help if you describe what you want to achieve in terms of input and output signals (problem statement) and not how you want to achieve something of which we have no idea. The more detail you provide, the better our answers can be.

 

[danadak]

One single chip possibility :



Here is whats on this chip, multiple copies in most cases, everything from simple logic to
complex peripherals like DSP Filter.....

Its routable internal and oput to pins. All resources have prewritten drivers so you just essentially
use high level f() calls to manipulate with the onboard ARM processor.



PSOC 5LP family.

Regards, Dana.

 

[danadak]

One single chip possibility :

View attachment 65177

Here is whats on this chip, multiple copies in most cases, everything from simple logic to
complex peripherals like DSP Filter.....

Its routable internal and oput to pins. All resources have prewritten drivers so you just essentially
use high level f() calls to manipulate with the onboard ARM processor.

View attachment 65178

PSOC 5LP family.

Regards, Dana.

Note because of 10V you would need external OpAmps to gain up to get the 10V full scale
you require. So my statement "single chip" is inaccurate.