Program selection pins - Switching voltage values

quintosardo · Post by **quintosardo** » Tue Jul 15, 2014 3:16 am

Hi all! First post

I wonder what switching thresholds are for program selection pins.
This is because I'm driving them through some diodes, so "tie to ground" is still about +0.5V.

Should it work?

Why diodes: to be able to select combinations through a single deck 1x8 rotary switch.

ice-nine · Post by **ice-nine** » Tue Jul 15, 2014 3:55 am

Using a n 8 postion switch with a network of diodes to output 3 bit hex works just fine. I've tried that before.

quintosardo · Post by **quintosardo** » Tue Jul 15, 2014 4:03 am

Thanks!

You used, like I'm doing, pull-up Rs and diodes to gnd, right? (Not the opposite, pull-down Rs and contacts to V+, like now I can see on the dev-board schematics).

quintosardo · Post by **quintosardo** » Wed Jul 16, 2014 3:35 am

To close the thread, I got it working perfectly.

- Program selection pins connected through pull-up 20k resistors to V+
- A 1->8 rotary switch selects a program. Its input pin to ground.
- Each output pin is connected, through low-signal diodes, to a sub-group of program pins

Presence of a diode in a combination is "1"
Absence is "0"