View Single Post
  #111  
Old 06-02-2007, 12:50 PM
b3lha's Avatar
b3lha b3lha is offline
Phil & Belha
 
Join Date: Aug 2001
Location: Alcyone Limited, Buckinghamshire UK
Posts: 2,671
Quote:
Originally Posted by cdvs
Quote:
Originally Posted by b3lha
The guys on the Legacy forum are using a simpler interface made from a couple of resistors, a diode and a transistor. See http://www.graphics.cornell.edu/~v/b10scan/ under "Serial Port".
What this simple circuit adds are always on request to send and clear to send signals. These signal lines were incorporated to overcome a devices processing limitations. This became a non-issue around 1970 and are rarely, if ever, used today. Anyway, what this stuff does is defeat their purpose. Something akin to fingernail polish. It might look good and doesn't hurt anything, but serves no useful purpose.
Please have another look at their circuit diagram. I don't think the circuitry they have added is "fingernail polish".

There is no wire connected to pin 2 (receive data) or pin 8 (clear to send) of the PC serial port. It looks to me like they are not using the UART in the normal manner. They seem to be sending and receiving the data one bit at a time by directly accessing the handshaking lines.
__________________
Subaru ECU and TCU Website
1992 Alcyone SVX Version L
1992 Alcyone SVX Version L
1994 Alcyone SVX S40-II
2004 Subaru Legacy 2.5 SE Sports Tourer
1996 Subaru Legacy 2.2 GX Wagon
1988 Subaru Justy J12 SL-II
Reply With Quote