Hi Richard

In fact we are using P0 to access 2*16 lcd module data bus apart from lot of external periperals like 16c552, 2*128KB NVRAM, 82C55 etc in one of our projects.

BUT Port 0 has to have a pull up of 10K (8nos). Lcd enable should be from a port pin to avoid timing issues for LCD module.

If any ISR is accessing the external devices, be sure to disable ALL interrupts to avoid conflict while accessing LCD module.


Could you post your circuit diagram?


V.Nagarajan