Re: BL2100 Expansion headers (LCD) to add extra IOs/Done

Group,

I have done this for years.  2-3 different designs.  One was a 4x20 LCD with keypad and a 8253 timer/counter interface.

Since you are missing the R/W line, some addresses are read, some are write.

Look at the schematics for the DIGI/Rabbit LCD/Keypad module, and it will show you how they did it.

A 74HC139 is the address decode and a 74HC245 to buffer the data lines.

Let me know and I send out a schematic of my design.  Is running right now commercially.

Dave