I'm currently wiring the signal of 16 potentiometers into a CD74HC4067 16 Channel Analog Multiplexer. The circuit is powered by the 3.3V signal on the Teensy 4. P0 (the first potentiometer) is wired to C0 (channel 0), but its value is read as the output to C0 and C1. P1->C1 has no effect, P2->C2 is read by C2 and C3. P3 has no effect and so on through all 16 pots.

Does this have something to do with the mux not receiving enough power? I didn't see anything on the datasheet about the signal splitting like this. On the Teensy forums I was told to not use the 5V signal as it could damage the T4.

Any help would be much appreciated! Thanks

Also, not an issue with code I don't think because the same channel reading works fine when I use 16 buttons

  • 2
    \$\begingroup\$ Schematic and potentiometer values? And it's too bad that the TI datasheet I looked at doesn't say much about \$3.3\:\text{V}\$ operation. In fact, they stay entirely at \$4.5^+\:\text{V}\$. \$\endgroup\$
    – jonk
    Sep 15, 2020 at 2:24
  • 3
    \$\begingroup\$ Have you checked the selection pins are actually receiving the signals they should? if S0 was stuck low it would explain the behaviour you are observing. \$\endgroup\$ Sep 15, 2020 at 2:32
  • \$\begingroup\$ @PeterGreen, yep, this setup works for my other mux with buttons, all selector pins are receiving signals ok \$\endgroup\$ Sep 15, 2020 at 3:15
  • \$\begingroup\$ Perhaps a damaged chip could cause this but I'd do more probing and try to figure things out before replacing it. The close connection to fingers and such like makes that a bit more likely. \$\endgroup\$ Sep 15, 2020 at 4:02
  • \$\begingroup\$ If you can read every other channel, the most likely explanation is that the mux select bit S0 is not working correctly. Either bad hardware connection, broken input or output pin, or just plain software issue, like wrong pin or pin not set to output. \$\endgroup\$
    – Justme
    Sep 15, 2020 at 4:41


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