In Marlin the display is configured by defining YHCB2004 and it resolves to HD44780 handled by marlinui_HD44780.cpp.
For Klipper I have it defined in the printer.cfg as:
[display] hd44780_protocol_init: True line_length: 20 lcd_type: hd44780 rs_pin: PD1 e_pin: PH0 d4_pin: PH1 d5_pin: PD0 d6_pin: PE3 d7_pin: PC1 encoder_pins: ^PL7, ^PG1 click_pin: ^!PD2
I have double checked with the schematic for the board that the pin-out is correct. The display is plugged in with a short ribbon cable that appears to work fine with Marlin. In Klipper the display back-light lights up and the display shows the first and third rows as just boxes with the second and fourth row just blank.
How can I diagnose what needs to be changed to get Klipper to init the display successfully? This is using the current stock v4.1b control board for the Geeetech A10x (and A20x) machines.
Thanks for any advise