Hi.

I have to build a small project in an 8051 kit with LCD and keyboard. The kit came with almost no documentation, and some (mostly non-functional) examples.

I'm having problems controlling the HD44780 LCD, because it is not connected to P1 and P3, as (almost?) all tutorials presume; it is connected directly to the data bus. From the examples, I found that writing to external ram address FF01 is like sending a command to LCD, while writing to FF11 prints a character on LCD.

Unfortunatelly, I can't use these addresses to read from the LCD (the LCD module catches reads from these addresses as bogus writes) and here is where all the examples fail. None of them verifies the busy status of the LCD, and I can't even implement it because reading these addresses messes up the display module.

After some tweaking with the kit, I found out that writing to FF21, FF41, FF61... has the same effect as writing to FF01, as for FF31, FF51, FF71... to FF11; but I still can't read from any of these addresses.

Does someone know how do I read the display's busy status from the data bus?

Thanks for any help.