>From memory I think this was done by using one of the other pins, like
RTS, CTS, DTR as the supply by driving them permanently high, but I am
not sure.
Best regards
			Luis


-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of Peter Feucht
Sent: 16 November 2007 12:39
To: 'Microcontroller discussion list - Public.'
Subject: [PIC]: RS232 to 5V interface without supply voltage

Dear Piccers,

I remember, that a long time ago I saw an application note for a
RS232-to-PIC(5V) interface which worked without any external power
supply,
but it took the needed voltages from some pins of the serial port. It
had
just a RS232 9 pole Dsub and 3 Pins (Rx,Tx,GND) on the PIC side.

I just googled but wasn't successful.

Does anybody remember such an application?

Thanks for any help and best regards

Peter


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