The MAX 233 is what we use--no external components--saves space, but costs a few bucks more... ---------- > From: Leon Heller > To: PICLIST@MITVMA.MIT.EDU > Subject: Re: UART levels > Date: Thursday, January 01, 1998 2:10 AM > > In message <199712312253.RAA18798@starbase.spd.louisville.edu>, "Jason > R. Williamson" writes > >I am using a PIC16C74A and the built-in UART feature. I am trying to > >interface to a PC Serial Port (standard RS232). However, I don't know > >if the PIC outputs are at RS232 or TTL levels. I suspect the latter, > >but I haven't seen anything in the data sheets definitively either way. > > > >Do I need a RS232 level-converting chip? What kinds are out there and > >what kind do you recommend? > > > >Thanks for your help, > > > >Jason Williamson > >- > > The outputs are TTL. You can get away without any level conversion, but > you will need to invert the signals, which you can't do very easily. The > best chip to use is a Maxim MAX202 - it's similar to the MAX232, but > uses .1 uF caps. > > Leon > -- > Leon Heller: leon@lfheller.demon.co.uk http://www.lfheller.demon.co.uk > Amateur Radio Callsign G1HSM Tel: +44 (0) 118 947 1424 > See http://www.lfheller.demon.co.uk/dds.htm for details of my AD9850 > DDS system - schematic and software.