> If I use the USART of the PIC16F627 (or any other PIC with an USART) in
> async mode to communicate with a PC via a RS232 serial port, do I need
> to a transceiver chip such as the MAX232,

Yes.  This has been beat to death many times here.  See archives.

For a complete PIC project with host communication via RS-232, see my HOS
project at http://www.embedinc.com/pic/hos.htm.  Schematics included.


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Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

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