*solved* Disable Shift Registers to direct buttons to different functions

[jrp]

Midibox LC uses 4 rows of 8 buttons/leds for track select, solo, mute and arm.

I would like to use 8 button/leds instead of 32 and -"how" is the question- flip between select, solo, mute and arm.

 

I am no programmer, so i am thinking about a different approach that doesn´t touch the code.

 

Is there a rude trick to wire the buttons/LEDs to all 4 DIn and DOut shift registers and always force 3 shift registers to be inactive?

A simple logic or a 4X4 Switch could be used to activate the registers. No idea if this is possible.

for a singe encoder i already did this using a simple toggle switch to select the pins it connects to, this can be useful for some custom applications...

 

 

 

EDIT: Instead of posting questions it is sometimes better to read a datasheet, pick up that old breadboard and do some testing.

 

For 74HC165 shift registers this exact behavior is possible by disconnecting Pin 1. This disables the parallel inputs, all other functionality of following chips is remained.

 

I know, you guys would do this with 3 lines of code anyhow...

But maybe this info is useful to some.

 

I´ll do some more testing, eg on how to parallel din chains. Possibly possible by or-ing one data line (?)

Could be useful if a user wants two (identical) control surfaces on his Midibox. One by the Computer, one by the mixing desk :)

Edited October 4, 2013 by jrp