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ZL3AI > APRDIG 03.10.03 09:35l 59 Lines 3024 Bytes #999 (0) @ WW
BID : 2058-ZL3AI
Read: GUEST
Subj: TAPR Digest, Sep 30, 1/16
Path: DB0FHN<DB0RGB<OK0PPL<DB0RES<ON0AR<WB0TAX<N1UAN<ZL2BAU<ZL3VML
Sent: 031002/1334Z @:ZL3VML.#80.NZL.OC #:9555 [Chch-NZ] FBB7.00i $:2058-ZL3AI
From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
TAPR APRS Special Interest Group Digest for Tuesday, September 30, 2003.
1. Re: Take Control of your DIGI (3)
2. Cheap GPS receivers / RS232 / Digitraveller
3. Re: Cheap GPS receivers / RS232 / Digitraveller
4. Nice points Tim & some questions for the gang
5. Re: Cheap GPS receivers / RS232 / Digitraveller
6. UIDIGI and DWAIT setting
7Office CD ROM( ! ). It's not neccessary. Just
keep hitting CANCEL on a half dozen or so popups...]
For the initial tests, I made a DB9 serial cable assembly. I cut a
standard telephone cord with modular connectors on each end in half. The
standard RJ-11 JACK has 6 contacts in it but the standard phone cords
usually have only the 4 center conductors. Fortunately, the Digitraveller
only uses the center contacts. The pinout and wiring is ridiculously
simple. Hold the modular plug of the phone cord so the side with the
locking tab is facing down and the cable exit is facing you; i.e. you are
looking at the flat side, not the tabbed side of the plug. Peer into the
clear plastic connector body with a magnifier and inspect the colors of the
individual wires crimped inside the plug. Positions 1 and 6 probably won't
have any wire. Counting from the left, note the colors of positions 2, 3
and 5. At the other end, connect these same pin numbers to the
corresponding pins 2, 3 and 5 of a female DB9 connector. You are done!
The unit started up and ran perfectly as soon as I plugged it into a live
serial port on a PC. I had heard rumors that the pin 4 line of the
Digitraveller cable had to be pulled up to +volts before it would run but
this isn't true. You DO have to have a positive voltage on the incoming
(RXD) line however to make it turn on. In other words, you have to connect
both the TXD and RXD lines of the DB9 (i.e. full two-way serial hookup),
even though you don't need to send any initialization commands to the
device. This simple 3-wire serial hookup will work with most commercial
software as-is. See below for null modem simulated handshaking info, if
needed.
More importantly, the simple 3-wire hookup works with the TH-D7 / D700s. I
took a 2.5mm stereo miniplug with a 5' cable molded onto it, and crimped
the the flying leads at the far end into positions 2,3 and 5 of a modular
plug. I used this cable to connect the Digitraveller to a TH-D7's GPS port.
Again, works perfectly. As soon as you turn on the TH-D7 and the outgoing
side of the GPS serial port goes into quiescent +volts state, the
Digitraveller turns on automagically.
This simple 3-wire serial hookup will work with most commercial software
as-is.
Stephen H. Smith wa8lmf (at) aol.com
Home Page: http://wa8lmf.com
Ham Radio/Mobile SSTV page: http://members.aol.com/wa8lmf/ham
APRS Stuff
http://members.aol.com/wa8lmf/aprs
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