Make sure the core frequency is locked. To do this you can add the following lines to /boot/config.txt:
$ core_freq=250
$ core_freq_min=250
you can increase these frequencies if needed for 4k resolution on the pi 4
to compile use:
$ make
to compile with debug info use
$ make debug
to compile with lots of debug info use
$ make debug2
$ sudo ./dgtpicom "a message"
you can add a beep and icons/dots:
$ sudo ./dgtpicom "a message" 1 31 15
$ sudo ./dgtpicom r 0 10 0 0 10 0
you can run Left and Right up and down with L,R,l and r
$ sudo ./dgtpicom
lever will pause, off button wil stop te app