I Finally got around to testing the code. I wired up a matrix keypad to a Leonardo.
I used this cheat sheet of Mach3 keyboard shortcuts.
I mapped the X Y Z axis jog keys and tried it on Mach3. It seemed to work fine. Now I just have to decide what other keys I want. I’ll finish the 15 key pendant soon. UI haven’t been in a rush since using the keyboard really hasn’t been to much trouble.
I put the updated code here:
https://github.com/rjkorn/CNC_Pendant
It still needs some work but I may just use a baby joystick instead and mount it on the corner of the machine near the E-Stop button. I know I have a couple of these lying around somewhere…

Then I could add a momentary center off toggle switch on the Z axis to raise and lower the spindle quickly.