Adding more switches/buttons/sliders/pots to your X10/S(Express) !

Since OpenTX v2.3.x was released some internal hardware was made available for use.
On the X10 PCB there are 2 connectors CON11 & CON12

These 2 connectors contain 2 inputs, one potentiometer input and a toggle switch input.

As I like my Xlite Pro, that has 2 momentary push buttons, I was really exited to mod my X10S Express to add some pushbuttons.

Check my thingiverse page for STL files: https://www.thingiverse.com/thing:4791528

As you can see I have added 4 pushbuttons, 2 at the front and 2 at the back.

As I said there are 2 connectors on the PCB that makes all this possible.
CON11 and CON12

Below there is a picture of such connector.
(I used a 6 pin connector (left over from a G-RX6 receiver) and cut off the 6th pin.)

Cables:
https://aliexpress.com/item/1005001535723660.html

In the schematic below you can see how to wire up switches to CON11 and CON12
As pin 1,2 and 3 are normally used for a Potentiometer, I had to create a situation that behaves like a voltage divider like that of a potentiometer.
What I am doing here, Is pulling pin 2 up to VREF with the resistor. This will force the input to stay at +100 in OpenTX at all times when the button is not pressed.
When pressed Pin 2 is fully shorted to pin 1, GND and will be -100 in OpenTX.
Pin 4 and 5 are already prepared to connect a pushbutton or toggle switch.

 

You can also add other (Rotary) switch configurations, or (Rotary/Slider) Potentiometers.

Example: 2 position switch + Pushbutton/switch

Example: 4 Position Rotary switch + Pushbutton/switch

Example: Slider or Rotary potentiometer + pushbutton/switch


The Design

I was searching the web for the most smallest and clean to mount pushbuttons. But for all of them you have to use a nut to mount them.
The problem is that the button immediately sticks out too much.

To solve this problem I used tact switches, with sliding caps.
These are 6mm x 6mm x 10mm tact buttons. Available everywhere on Aliexpress or Ebay. Just search for tact switch.

Tact switches:

https://aliexpress.com/item/1058764733.html

Switch caps:

https://aliexpress.com/item/32763659857.html

I chose tact switches because then I could design a simple bracket in which they are recessed, and I can determine how far the caps of the tact switches protrude.

Only now I had to find a way for a bracket that could fix as much as possible without extra fixings.

For the front I could make perfect use of the switches that were already there. Coincidentally, these switches were already in a kind of bracket that prevents them from turning around. So I could perfectly draw a new bracket for this that fixes both the current switch and the new push button.

The images below show the brackets, with the position of the new push buttons relative to the current switches.

 

To be able to drill exactly the holes for the push buttons, I drew a drilling template, which you press into the 2 holes of the current switches. The hole gives the exact position of the push button.
Drill the hole through which the cap of the push button comes to 6.5mm, first start with a 3mm drill.

For pilots holding the transmitter, the push buttons are in a perfect place.

Same for the back. You slide the drilling template below internally against the external module bay. Then drill the button holes with 3mm and the hole for the mounting screws with 2mm

Then drill out the holes for the push buttons with 6.5mm and countersink the 2mm hole on the outside.

Drill the small holes that will be used to secure the bracket with 1.5mm (NOT WIDER!)

On the back of these push buttons I soldered a small printed circuit board with the resistor and capacitor. I have used SMD, but you can also use ordinary conventional components for this.


Clear photo of how to connect the wires to the PCB / push button. I have used appropriate wire colors.

RED = VREF

BLACK = AGND
WHITE = EX1 / EX2

When everything was ready, I sealed the soldering work.


OpenTX Configuration

To configure the new push buttons, go to the System menu, Hardware tab.
Set EX1 and EX2 to be “Multipurpose switches”.

And set for SI and SJ to be “2POS” switches.

Because EX1 and EX2 are not real switch (on / off) inputs. they must be configured in the model in such a way that they act like on / off switches.

In the logical switches menu I have created 2 logic functions that make this possible.
I used the last positions for that.

Simple method but works perfectly.

L63 is not active until EX1 is -100.
The same goes for L64 / EX2.

L63 and L64 are now available as switches throughout OpenTX.

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