Digital potentiometers

[xtian]

Interesting stuff!

https://youtu.be/uezoQ5fkixY

[dorrisant]

I've been wondering about the possibilities... need datasheets... for... parameters. No, damn it! I have too much to do as is.

[katopan]

I built a custom digital volume pedal for someone a few years ago, which was my first look at digital pot chips. Once I worked out the right one to use that had the serial comms setup I wanted to use with the Arduino that controlled it, it was a breeze and worked great. The analogue side was just literally a dual opamp set up as a buffer and a gain stage with the digital pot set up as a simple volume between them. The idea was to have up and down footswitches which stepped the volume up and down by set amounts across a range. I put a trimpot on the board as well which made the step size adjustable between 1dB and 3dB.

Endless applications and not complex to interface.

[xtian]

I built a custom digital volume pedal

You avoided the issue by stepping up and down, but I was wondering about "zippering." These chips have a fixed number of steps (256 for some better ones), so smooth volume sweeps may be impossible. True?

[katopan]

I don't know that it's much of a problem, but yes my pedal avoided it. My stereo at home only have 64 steps on the volume control and you don't really notice the steps as you turn up and down. With 256 step resolution it is probably more than adequate. Depends what parameter you're controlling with it of course (not everything is just volume control).

I used a chip with 256 steps (AD5260) and because I was stepping in dB, so it was exponential. I worked out a spreadsheet for all the step values of 1-3dB in increments of 0.2dB and programmed them as array look-up tables in the Arduino.

[JazzGuitarGimp]

In my 40-some years of working in electronics, I have made a number of attempts to learn code. Every time was a complete failure. My brain just isn't wired that way. It makes my head fell like an explosion is eminent....

[Phil_S]

In my 40-some years of working in electronics, I have made a number of attempts to learn code. Every time was a complete failure. My brain just isn't wired that way. It makes my head fell like an explosion is eminent....

I'm good or at least passable at all sorts of things for which I never had any formal training. I'm with Lou on this one. It's not that I can't. I don't want to because I have a high failure rate. I glaze over at the thought of it. I have no sense that I can master it. Maybe I'm wrong about this?

My frame of reference is Visual Basic for Excel. A number of years ago, I authored an enormous (to me, LOL, I just looked, less than 400 rows of code) macro to take data from one accounting system and rearrange it so it could be read by another accounting system. Through sheer persistence, I got it to work consistently and to work well. However, it took far too many hours to get it to do what was needed and, in the end, I realized the code I wrote as far from elegant. It was in my view, embarrassingly poorly written and probably rather inefficient. I did not bill the client for this work. It is good that I did it for a non-profit organization that has a mission I support. I didn't feel bad about giving it away, but I felt that I had very little aptitude for that sort of thing.

Where does one learn to work with something like Arduino and achieve a reasonable level of competency? Consider that I couldn't gain any real mastery over VB. Maybe I should just spend my time on other things. Oh, never mind, really, I shouldn't. (glazed over)