Advice on choosing components for control system - Page 1
Forum section: electronics / beginners

author: homelykoala
author_rank: Newbie
timestamp: November 12, 2024, 01:00:18 am
content: 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 abuild like this onewhich 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 Moreover, after talking with Analog Devices, the AD7734 seems pretty out of date and the resources on its eval board are a little sparse and the linked build does some fiddling with some jumper pins which I think I'd have to consult with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 theAD7124,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 theSTM32F serieswhich 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

author: PGPG
author_rank: Frequent Contributor
timestamp: November 12, 2024, 02:14:32 am
content: From your description it seems that may be you don't need microcontroller at all. To keep few DC signals at some defined voltages having regulated supply you need only resistor dividers. If load at these output changes than instead of resistor dividers you can use adjustable voltage regulators.DSP chips are intended to allow you to process fast changing signals through complicated math formulas (implementing specific filters and so on), I think (I have never used DSP).Since 12+ years we use AtXmega 8 bit microcontrollers. As you can read at first page of ATxmega64A3U/128A3U/192A3U/256A3U (differs in flash size) datasheet:https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-8386-8-and-16-bit-AVR-Microcontroller-ATxmega64A3U-128A3U-192A3U-256A3U_datasheet.pdfall they have two sixteen channel 12 bit 2 Msps A/D converters. If 12 bit is not enough for you than microcontroller families having 16 bit ADCs certainly also exists.

author: jonpaul
author_rank: Super Contributor
timestamp: November 12, 2024, 04:42:47 am
content: use simple analog ICs.See Nat Semi, Linear Technology, app notesHP, Burr Brown Power supply handbooksJon

author: homelykoala
author_rank: Newbie
timestamp: November 12, 2024, 05:36:26 am
content: With this approach, I guess the setpoints would be defined by some voltage references, but we want to be able to change these setpoints in software so the voltage references would have to be digitally controlled. At that point, is it still beneficial to use this analog approach over a digital one?

author: jonpaul
author_rank: Super Contributor
timestamp: November 12, 2024, 05:41:38 am
content: First engineering rule:KISS Keep it Simple Stupidj