Papabravo
Well-Known Member
Almost every 8051 has at least one onboard UART or Serial Port. If you need more there is the very capable MAX3100 family of SPI UARTs, or you can build one in software. I agree with Nigel, by the way, that you dont need to use interrupts for everything especially keypads. I also agree that multiple processors are not indicated for this straightforward application. You do not appear to have the slightest justification for using more than one processor.