7. Thinking about interaction

Something I have to start thinking about at this point is how will I interact with these screens. All the ones I purchased for experimenting have touch capabilities. Some are capacitive, some are resistive. Both have their differences, so should I go in that direction? On one hand they all already come with it, but then there's about 4-5 more connections I need to solder on each screen for touch, and from the tests I've done... it's a bit finicky.

But what exactly do I want to interact with and how? For starters if I'm going to build a device that supports multiple instruments, I need a way to selecting which one I want to display. Is touch really a good choice for something like this? And, if we look at the instruments in a typical cockpit, most of them have knobs and buttons.

Alternatives

1. Touch:
   1. I'll be drawing a lot of stuff on tiny 3.2" screens, so I don't have a lot of room to add buttons. I played around with the idea of having the screen divided into 4 sections so I could use those as buttons, but for things like increasing/decreasing a heading bug on a Heading Indicator, a barometric pressure on an Altimeter, or an OBS on a VOR, it's unpractical.
   2. Pros:
      1. Already comes with the device
   3. Cons:
      1. Extra wiring
      2. Finicky and unpractical code
2. Push Buttons
   1. I tried adding two buttons to each screen for going back and forth along the screens, but that was about it. I even 3D printed an oval shape cap for the 2 buttons that pretty much looked like the buttons on a DVD player for fwd/back that looked really good but I felt was only solving half of the problem.
   2. Pros:
      1. They are pretty straightforward to add and implement
      2. They are more reliable than touch on these type of devices
   3. Cons:
      1. Only solved half of the problem
3. Rotary Encoders
   1. I messed around with the idea of a rotary encoder or two. Usually they come with an integrated push button so between two knobs and two buttons I would have more than enough inputs for the instruments I want to design
   2. Pros:
      1. With the rotary encoder, I could control different values that I could increment and decrement
      2. I also had available 2 buttons to assign to anything I needed
   3. Cons:
      1. There was really not a lot of room to put two rotary encoders on these small scale screens I'm designing, especially when everything is built and soldered by hand and with off shelf components.
4. Dual Rotary Encoder
   1. Pretty much the same as having two rotary encoders but in the space occupied by just one, but with the trade-off of only having one button instead of two.
   2. Pros:
      1. Same as two rotary encoders plus one is easier to mount and solder than two.
   3. Cons:
      1. They are a bit more expensive than regular rotary encoders

The Choice

After a lot of experimentation and testing, I decided to go with the dual rotary encoders. The extra cost is worth the simplicity and reduced space. I went with this one from Digikey and did not disappoint.