Teensy LC and 74HC4067 16 channel multiplexer wiring

[oddson]

GND. IIRC, the input/output switching with these MOSFET switches is basically floating (within the allowed limits) and only the control section refers to VSS. Even a very dirty GND could not "modulate" the switches' on resistance strong enough to see any effect.

Is that jibber-jabber for 'use GND' or 'it doesn't matter'?

If AGND isn't better then I suppose using it could be a source of noise for the voltage dividers so GND is preferred.

(edit. - lol - I thought IIRC was some electrical thing I didn't understand instead of a blog shorthand. Threw me off reading 'GND' full stop!)

 

[Theremingenieur]

Sorry if I weren't clear... GND is definitively preferable to connect the MUX VSS. See the first 3 letters of my previous post...

 

[umby68]

That diagram looks fine.

The 74HC4051 works the same way, except it is only 8 signals instead of 16, and it takes only 3 wires to control instead of 4.

There are many possible ways to use 8 of these to get 64 inputs. But the simplest way is to use 8 of the analog input pins on Teensy, where the output of each 74HC4051 connects to a different analog input pin. The 3 control signals are connected to the same pins on all 8 of the 74HC4051.

You can find a diagram on the MIDI page. Scroll down to "Connecting Many Buttons & Knobs/Sliders".

https://www.pjrc.com/teensy/td_midi.html

Good morning

I am looking to develop this project as per the mentioned scheme and with 74HC4067.
In the Sketch (File > Examples > Teensy > USB_MIDI > Buttons) I see that a pullup resistor is foreseen but on the scheme
https://www.pjrc.com/teensy/td_midi.html there isn't a resistor.

Can you help me to understand?
Thanks a lot

 

[umby68]

I try to understand this possibility to have 16+16+16....push buttons controls with CD74HC4067 and Teensy 2.0
Can somebody help me?
Is the following diagram correct?

Thanks a lot for your collaboration

 

[BriComp]

You could try one of these which will scan up to 64 keys. The IC does the scanning and reports to Teensy when key(s) pressed.