This is for a tactile combination scroll wheel & pushbutton assembly. TSW Switch This switch includes a quadrature encoder for rotary as well as several buttons for up, down, left, right as well as a center Enter button.

enter image description hereenter image description here

I am making a pcb for the above schematic. S1,A,B go to COM A and S2,S3,S4,S5 go to COM B but all 7 each are going to have different functionalities when they are clicked but they are grouped in a set of 3 and a set of 4. As a thru hole pcb do I have 7 hole for each or just 2; one for COM A and one for COM B. having 2 seems to be what the schematic is showing.

My question is though, if I only have holes for COM A and COM B, how will it differentiate that S2,S3,S4,or S5 was clicked in COM B or S1,A,or B was click in COM A

But if there are thru holes for all seven then I can easily tell which one of the seven was clicked but that doesn't seem to follow the schematic.

Any insight is much appreciated. I'm am very new to electrical engineering and am a hobbyist so let me know if I didn't explain something correctly or if more information is needed to answer my question. Thanks - Jeff

  • \$\begingroup\$ Maybe I don't understand your question, but your holes in the pcb should match the pins on the parts you're using. Do you have 7 separate physical switches? Or do you have a multi-switch unit like a DIP switch, somehow with two common pins? \$\endgroup\$ Jan 9, 2017 at 21:44
  • \$\begingroup\$ It is a multi switch unit: digikey.com/product-detail/en/c-k/TSWB3NCB222LFS/CKN10345-ND/… \$\endgroup\$
    – jeff
    Jan 9, 2017 at 21:53
  • \$\begingroup\$ Can you close the switch one at a time? I am assuming you are going to have only one signal going from COM A through either A, B, or S1. Right? It seems like you are trying to use a master/slave type of system to communicate signals from one device to another. \$\endgroup\$
    – 12Lappie
    Jan 9, 2017 at 21:57
  • \$\begingroup\$ Ok, that's one strange switch. Yes, you want one hole for COM A and one hole for COM B on your PCB. If you're asking how your circuit can differentiate which button was pressed, do something like: Connect COM A and COM B to ground. Put a pull-up resistor on each switch output, and connect these 7 switch lines to your microcontroller. (Are you using a microcontroller? Some hints about what you're doing would help.) Each switch can be read as 1 when not pressed or 0 when pressed. A and B are quadrature signals indicating rotation of your switch - that's a separate issue. \$\endgroup\$ Jan 9, 2017 at 22:03
  • \$\begingroup\$ That's where I was confused because like you said there is only one signal coming from COM A which means I can't differentiate which one of the 3 its coming from and same goes for COM B \$\endgroup\$
    – jeff
    Jan 9, 2017 at 22:38

1 Answer 1


You could connect Com.A and Com.B to a common ground and then do your switch detection using pullups to the appropriate signals

The datasheet provides all the required information. You have 4 wires A, B, Com.A, Com.B (grounds I'd suggest) for the rotary function and the phase relationship of the signals tells you the angular position.
If you are using both Scroll, Jog and Push, then the connections are:

enter image description here

So Com.A and Com.B are your Grounds

Com.A --> A & B your quadrature scroll
Com.A --> S1 is Push
Com.B --> S2, S3, S4, S5 are your Jogs


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