Date: Mon, 5 Dec 2005 00:26:00 -0600 (CST)
Subject: RS-232 to TTL serial level converter
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Not much interesting done this weekend - just a level converter between 
RS-232 (officially EIA-232) and TTL serial. I need this so the laptop can 
use the embedded radio and GPS modules I have that operate at 5 volt TTL 
(transistor transistor logic - approx 0 to 1.4 volts is logic low and 2 to 
5 volts logic high).

The RS-232 serial port is a standard female DB-9. This connects to the 
laptop. The TTL serial port is a RJ-45 jack. Two pins are for 5 volts and 
ground. The other two pins are for transmit and receive. I'll add RJ-45 
pigtails to the radios and GPS receivers.

Unfortunately, the wiring sticks out too far from the bottom of the board. 
It won't fit inside a Penguin Peppermints tin like I had planned. The 
enclosure isn't a priority, though.