For 1-32 on then 32-1 off, you need bi-directional shift registers and some steering logic.

I think the bar graph showing the charge of a capacitor will climb from bottom to top until all the bars are lit. When power is shut off the cap discharges and the graph falls from top to bottom. The only caveat is that the bar graph will need an independent source of power.

I'm not PUSHING to have my solution adopted, just think it will serve the stated purpose. The only difference is that the TS wants 32 LED's whereas three 10 LED bar graphs will give only 30. If 32 is necessary then another solution will be needed.

That's all the input I can offer. Unless I think of something else - I'll largely stay out of this.

 

It's always a tradeoff, the 3914 can directly drive LEDs but the registers "may" need drivers, and of course the regulator if needed for a shifter in a 12 volt circuit, so yea...it's always give and take.

The register suggested earlier can drive a good current from any output, but the total is limited to 50mA.

 

The TS mentioned only digital chips in his question, which steered most of us to a digital chip solution.

The bar graph display approach certainly will work. However, it needs a bi-directional linear ramp input for an even-stepping display. Not at all difficult, but probably not something anticipated by the TS.

I did a quick innergoogle swim for cascading more than two 3914's, and did not find much. Here is a link to another thread, but the diagram links are broken.

https://www.electro-tech-online.com...r-dot-displays-a-complete-explanation.126056/

ak