I'm using a 8051 with a single UART. I've got a max232 and a Microchip IRDA chip that both interface using serial. The software doesn't care which device is providing a link via IRDA or serial and it's just serial data all the same to the software.

I know that hooking up a PC via serial port and IRDA at the same time would cause havoc, so this is clearly marked so that the user won't do it.

But how would I connect both chips to the same TX and RX pins such that they won't be damaged? A diode?

For example, with no connection on the IRDA, I suspect that it's output (Tx) would be driving 0 or 5 volts. And at the same time the MAX232 may be driving as well.

Anyway to protect this and keep the two devices sharing the UART for software ease?

TIA
John Tyler