CarBytes

[Ludis Langens]

Toby Corkindale wrote:
> 
> Is that convertor suitable for the '808 with the 160 bps (not 8192 bps)
> transfer rate?

Not on the '808.  But it should work for 160 bps output from a '165. 
Doing so would require pulling tricks with your UART though.

I've breadboarded an optoisolator based circuit that interfaces ALDL to
a Macintosh RS422 serial port.  It steals power from the computer's
serial port.  It doesn't use a MAX232, any discrete transistors, or
extra logic chips.  The hardware's been tested with simulated ALDL data.
 Software to receive 160 bps data has been proven.  But, I've never used
the circuit to monitor real ALDL communications.  It also hasn't been
tested with a P4 ECM with the 64606 chip.

Parts count for receive only 160 bps:
  1 specialty optoisolator
  5 signal diodes
  1 capacitor
  2 resistors

Add for receive only 8192 bps:
  1 resistor

Add for bidirectional 8192 bps:
  1 generic optoisolator
  2 resistors

Add for computer control of the ALDL mode (10K and open modes):
  1 generic optoisolator
  2 LEDs (status indicators)
  2 resistors

Add for fuel pump circuit (ALDL pin G) monitoring:
  1 generic optoisolator
  1 zener diode
  3 resistors

This circuit could be adapted to an IBM PC's RS232 port with minimal
modifications.  This'll work with any computer except one which requires
negative voltage RS232 inputs but doesn't drive it's outputs negative. 
Is there any interest in this circuit?

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/