Now it's time to work on the shoulder buttons. The two buttons I used in this project are 2-terminal versions that come with extra long legs. The ones included in the kit have four legs. You only need to use two of them.
Measure Shoulder Button Wires
Layout the two buttons and plan out the lengths of each wire. The L and R shoulder buttons will need to be connected to the last two remaining pins on PiTFT (#20 and #21) and the remaining ground pins on the Gamepad PCBs.
Shoulder Button Wires
Once you've measured each wire, we'll prep them by striping and tinning the tips. You'll also want to tin the leads on each button.
Connect Wires to PiTFT
Connecting the left shoulder button to the PiTFT is a little tricky because it needs to be threaded through the PiTFT and Raspberry Pi. Using the similar method we did when connecting the gamepad PCB wires to the PiTFT, the tinned tip of the wire should be able to poke through pin #20. Once it is, solder it in place. The right shoulder button is much easier to connect since pin #21 is close to the edge.