Hello, my new Project allow you to connect a standard LCD and a lot of Push-Bottons via I²C to your Device.
Easy chance again normal LCD - Easy to use C-Code Samples.
Use like an EEPROM Slave. I2C Adress 0x54 or other(programmable).
Send 00 / xx / yy
00 : Adress 00
xx : Data or Command to Display
yy : 00 = nothing to do / 01 = xx=Data / 02 = xx=Commando / 04 = LED on / 08 = LED off
If Busy also communication to LCD, 0x54 will be NACK!
Set Adress: 0x54 0x02 (Pointer on adress 02)
Read 0x55 return Key-Code 1, 2 or 3 and delete Keybuffer.
You need Only 4 Wires and my little SMD Circuit.
Long distances to LCD allowed, short connection between MCU&LCD.
See the schematic, the C-all in one Code for AVR-Studio. Good SampleCode for Master in "Ansteuerung.zip"