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Re: [gpsd-users] Sending SiRF commands to GPS receiver

From: Eric S. Raymond
Subject: Re: [gpsd-users] Sending SiRF commands to GPS receiver
Date: Sun, 26 Feb 2012 14:59:00 -0500
User-agent: Mutt/1.5.21 (2010-09-15)

Alexander Carver <address@hidden>:
> -x
>     Send a specified control string to the GPS; gpsctl will provide
> packet headers and trailers and checksum as appropriate for binary
> packet types, and whatever checksum and trailer is required for text
> packet types. (You must include the leading $ for NMEA packets.)
> When sending to a UBX device, the first two bytes of the string
> supplied will become the message class and type, and the remainder
> the payload. When sending to a Navcom NCT or Trimble TSIP device,
> the first byte is interpreted as the command ID and the rest as
> payload. When sending to a Zodiac device, the first two bytes are
> used as a message ID of type little-endian short, and the remainder
> as payload in byte pairs interpreted as little-endian short. C-style
> backslash escapes in the string, notably \xNN for hex, will be
> interpreted; additionally, \e will be replaced with ESC. This switch
> implies -f.
> While it doesn't lay out the format explicitly as a full command
> line example, it does document what bytes go where and what may be
> needed for each one including which bytes should appear first.  It
> just happens to leave out SiRF.

Yes, it does.  I'll fix that now.  How's this?

For all other supported binary GPSes (notably including SiRF) the
string is taken as the entire message payload and wrapped with
appropriate header, trailer and checksum bytes.
                <a href="";>Eric S. Raymond</a>

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