At 04:53 PM 11/21/02 -0600, you wrote:
>Yes it can, many people use it. I don't have a schematic I can share
>though. Another chip to look at is the Maxim MAX485. Lower power
>consumption I believe. And, this may just be semantics (and I'm sure
>I'll get corrected if I'm wrong), but the PIC UART isn't RS232. It's
>TTL. Once you add a convertor circuit, it then becomes RS232.

CMOS (output) or TTL (input) levels, asychronous serial. To make it
into RS-232 you need to invert the signals and shift the level to
RS-232 levels. So, it's "almost" what we loosely call RS-232 but
not quite.

If you want to just put a connector on the board hooked to the PIC
for occasional RS-232 connections for setup or whatever, I think
James N. has a MAX-232 type circuit in a dongle for a reasonable
price.

With the RS-485, you can certainly use the chips mentioned, but
another port pin usually needs to be designated to control the driver
enable for the typical half-duplex communication.

Last I looked, the bipolar 75176 was cheaper than the CMOS alternatives,
so unless power consumption is important you might want to look at it
for that reason.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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