http://www.piclist.com/techref/io/serial/ttl-rs232.htm Lists all the methods I know... did I miss any? James Newton, PICList Admin #3 mailto:jamesnewton@piclist.com 1-619-652-0593 phone http://www.piclist.com ----- Original Message ----- From: Byron A Jeff To: Sent: Sunday, January 21, 2001 09:17 Subject: [EE]: How can I put together a discrete RS-232 level translator? I'm current using Wouter's Wloader and Woj's linwload to program 16F877 parts. You can find the wloader homepage here: http://www.xs4all.nl/~wf/wouter/pic/wloader Wouter uses a discrete level translator to build a single pin interface between the PIC and the serial port. It consists of a 330 ohn and two 10k current limiting resistors, a 47k pullup and 5V zener that translates the -12/12V RS-232 to 5/0V for the PIC. Unfortunately it doesn't work with my serial port, which seems to require the standard +3/-3V thresholds. Wouter points out that a MAX-232 interface can be built to maintin proper RS-232 levels, but I'd prefer not to have to wire the entire chip to maintain proper RS-232 levels. So I'd like to get some advise about wiring a transistor switch to switch the -12V available on DTR instead of passing 0V. So that 5V will pass 5V but 0V will turn on the transistor and pass -12V. This question in general is how to switch a larger magnitude voltage with a smaller magnitude control signal. I need a simular circuit for switching Vpp with 5V. Any suggestions will be welcome. BAJ -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu