Re: [NTLK] Technical: GPS, the Newton 120, RS-422 and NMEA 0183 protocols

From: Victor Rehorst (
Date: Tue Nov 16 2004 - 06:16:52 PST

RAParker wrote:
> How successful am I going to be, trying to get my Newton 120 (v1.3 or
> v2.0) to communicate with the current crop of high tech, miniature GPS
> devices?

Probably pretty successful if you stay with OS 2.0. Probably the only other
GPS software running on 1.3 is Teletype GPS.

> Specifically:
> 1) I've seen (relatively) cheap, mini GPS receivers on eBay, which
> utilize PS/2 ports for RS-232 communications and 5v-9v power. The link
> to the PDF manual for the device is here:
> I want to build a small project box with 4 AA NiMH batteries, to supply
> power to the PS/2 connector, plus provide a Newton compatible DIN 8
> RS-422 serial cable for the RS-232 signals from the device.

Cool. Sounds like a fun and easy enough project.

> 2) GPS Map Lite v1.2 (freeware) looks pretty impressive and runs on my
> MP120 so my questions are about using GPS Map Lite this type device.
> a) From the GPS Map Lite manual: The Newton compatible PDA has a mini
> DIN 8 female connector with RS422 levels. For making it RS232
> compatible normally pin 8 must be connected to pin 4.
> I imagine this applies in the case of this receiver mentioned above
> because the receiver does provides both, RS232 and TTL on PS/2 pin
> outs, I would simply ignore the TTL outputs.


> b) GPS Map Lite is aware of four NMEA 0183 message combinations:
> or $GPRMC alone.
> The Polstar receiver says it provides NMEA 0183 GGA, GSV, GSA, RMC,
> (optional VTG, GLL)
> Sounds like it should work, no? Does anyone have any experience with
> GPS Map Lite on their Newton using an external GPS device?

I'm sure lots of people have. The Delorme Tripmate used to be a popular
low-cost external GPS receiver. It was basicially a large-ish yellow box with
a serial cable sticking out of it. It was powered by internal batteries but
could be modifed to use an external power source.

Me personally, I have a PCMCIA card, but functionally it's all the same...

Good luck with GPS!

Victor Rehorst - -
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