Bill & Pookie wrote:
> Thinking of multiplexing the UART.  Connecting the Tx and Rx pins  of
> the pic's UART to a input pin and a output pin on the same pic.  With
> this you can read the state of the UART's Tx output and the other pic
> output pin can work the UART's Rx input.  All under program control.
>
> Now use two more pairs of the same pic's pins as input and output
> hooked to the proper receiver/transmit drivers for the units you are
> interfacing. Software must set a flag for which device communicates is
> to take place. Then often, but not at a precise time, read the input
> pic pin for the selected device and set the UART's Rx pin accordingly.
> Same for transmit except read the pic pin connected to the UART's Tx
> pin and set the proper device's output pin accordingly.  Let the UART
> do all the time critical bit banging.

Or if this is a low volume or hobby product, just use a 18F6520 with dual
UARTs and be done with it.  Microchip is coming out with a 40 pin PIC with
dual UARTs, but I don't think it's available yet.

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