Anet A6 Firmware LCD Control

Hello!I have uploaded Marlin 1.1.9 to my Anet A6. After installing the u8glib library and Anet A6 configuration files, I uploaded Marlin to my printer. The LCD was blank. I changed the LCD display from ANET_FULL_GRAPHICS_LCD to ZONESTAR_LCD (it is like the standard Anet A6 LCD 2004 but with five buttons instead of a dial). The printer LCD started and all of the information came up. However, when I tried to use all the options (PREPARE, CONTROL, PRINT FROM SD, etc.), I was just sent back to the homescreen. Attached is an image with the directions on how to set up the ZONESTAR_LCD. It says it needs ADC_KEYPAD_PIN to be assigned to an analog pin. I searched throughout the Marlin files and couldn't find out how to assign it to something. I would really appreciate some direction on what to do! Thank you!

If you didn't find a solution, just load the example configuration files found in Marlinfolder for Anet A8.
It's the same mainboard and buildplate , you already have the Anet A8 display with the 5 buttons ( comes with Anet A6 autolevel to save flash memory) .

I have noted that Marlin 1.1.9 had problems and you should use Marlin 1.1.9BF

OR

You could choose to upgrade to Marlin 2 as I am using Marlin 2.0.6 on My Prusa Compatible 3D Printer with Arduino Mega 2560