PowerBook 100/CM4 - Convert Analog Brightness/Contrast wheels to Digital Inputs?

[Trash80toHP_Mini]

Need help on this one gang. I'd like to develop a circuit to use the OEM board's potentiometers to act as the four Menu Buttons on the LCD Controller's input board if possible. Don't need power switch, when system powers up the screen turns on, power down and it's off.

- rotation of wheel to minimum setting blips one momentary switch input for SOURCE
- rotation to maximum setting blips momentary switch input for MENU
- right side pot would be + - inputs
- repeated rotations from neutral to max or min would be same as hitting momentary switch on control board repeatedly
- any setting between max/min ignored as neutral (near max/near min?)



I've probably got cubic to install or solder a hat down to the CM4 I/O board for the purpose. CM4 won't be doing anything else while I may be adjusting the LCD. If not I can add another RPi Pico or Arduino into the mix for a total of four CPUs on board.



So much of this project is above my pay grade, but plugging away one bit at a time. Any help much appreciated.

 

[Trash80toHP_Mini]

Been looking into this a bit further:

Feed power to the OEM pot card
GPIO measures resistance of current induced by potentiometer
GIVEN: mid-range resistance = NEUTRAL
IF: resistance level drops to X
THEN: blip 1
IF: resistance level rises to Y
THEN: blip 2

Might be time to learn MicroPython . . . unless there's a Basic interpreter for Micropython?


edit: yay!

https://blog.adafruit.com/2021/11/12/a-basic-interpreter-written-in-python-runs-on-microcontrollers-python-basic-vintagecomputing-hackaday/

 

[twelvetone12]

I think you could just read the two pots with two ADC channels, it will read a min and max value and then you can convert that in whatever you need.
What is PowerBook 100/CM4? Is it replacing the logic board with a RpI?

 

[Trash80toHP_Mini]

I think you could just read the two pots with two ADC channels, it will read a min and max value and then you can convert that in whatever you need.

Still need the NEUTRAL position, is that doable under your setup?

Yep, replacing all the guts of the PowerBook 100. But it's the Compute Module version that came out a few years ago. CM5's out, but sticking with the original concept for dream machine.

PowerBook 100/RPi-CM4-Lite

PowerBook 100/2300c LCD/Logic board upgrade has been in process for well over a decade. This revision has been on the back burner since the Compute Module 4 first came out. The I/O board makes it perfect for this upgrade of my beloved BabyPB, very first laptop, bought new and maxed out in the...

tinkerdifferent.com

Pi Pico above battery bay converts Keyboard switch matrix to USB.
Arduino Micro above TrackBall converts its ADB output to USB.
Arduino next to it will run the pot board that replaces LCD controller board above it in the pic.
PicoPSU (connector removed/hardwired) provides regulated power for everything

Keeping battery bay open, wondering the 6V of new build cell can be upped to 12V for use untethered?


edit: the I/O board for CM4 is relatively inexpensive, so I can get another one for the Duo attempt. Just swap the CM4 between hacks and custom case.