I've had a look at that hobbyrobotics project.

It uses µC Usart to receive serial data and convert it into parallel outputs / signals for the classical 16x2 or 20x4 LCD display ; and a PWM (not mandatoty) to drive backlight.

So I'm sure it can be done with an AtMega8.

I've build a serial (UART-TTL) display for my OSIMPLC (Open Simple Industrial Modular PLC), Open Hardware + Free Software project , see https://osimplc.com.

It works very well with PIC16F887 and ATmega1284P.

These are the microcontrollers implemented in OSIMPLC and can be programmed using LDmicro, Great Cow Basic (and the ATmega1284P using Arduino IDE and Mighty Core plugin).
I supose that any microcontroller that has at last one UART can drive this serial LCD, because it has few control codes, and can receive and send ASCII codes.

This serial LCD (OSIMPLC-HMI) is based on the old (and dead) LCD SMARTIE open project, and uses a subset of Matrix Orbital commands.

The HMI has a parallel 2x16 LCD display, and four buttons that sends 'A', 'B', 'C' and 'D' ASCIII characters over serial; it's controled by a PIC16F628A, two BC548 and a bunch of pasive components.
All components are THT, and PCB has two layer with metalized holes.

The HMI has five pins: Vdd (+5V), Rx, Tx, Reset and Ground. Driving Reset pin high resets the PIC16F628A, allowing to resume communications from the main microcontroller in case of an unexpected "hang".

It's based on x7jay7x open hardware, his project was available at http://www.freewebs.com/x7jay7x/ , but now this URL has no content...

The firmware is a slightly modified version of the original by x7jay7x, suited for my project.

You can download the OSIMPLC Kicad design files and Gerber files from https://github.com/osimplc/osi...iles/5699404/OSIMPLC-kicad.zip and https://github.com/osimplc/osi...es/5699403/OSIMPLC-gerbers.zip

The firmware can be dowloaded from https://osimplc.com/docs/es/downloads/OSIMPLC_HMI_firmware.zip

This design has been released under CC BY-SA license, you can freely use it in your projects, attributing my work and delivering modified versions with the same license.
Sadly, x7jay7x is not reacheable through LCD SMARTIE forum, and his colleagues has no contact with him from several years...

Best regards
DanielH

Everything you can make with a PIC can be made with an AVR, the question is who is going to do that?

Since I'm not using AVR's it won't be me ;)

You cannot convert that LCD program (in basic) to ladder.
Basic can do extensive string operations and LDmicro cannot.

Buy yourself a pair of 16F628a pic's and program them, there are plenty of easy programming solutions on the internet.
After that you can continue working with AVR controllers.