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

From: Alexander Carver
Subject: Re: [gpsd-users] Sending SiRF commands to GPS receiver
Date: Sun, 26 Feb 2012 11:47:37 -0800
User-agent: Mozilla/5.0 (Windows NT 5.1; rv:10.0.2) Gecko/20120216 Thunderbird/10.0.2

On 2/26/2012 11:43, Eric S. Raymond wrote:
Alexander Carver<address@hidden>:
Right, I understand that much but what should the format of the
command be after -x because it's not documented for SiRF.  The
manpage for gpsctl lists UBX, Navcom NCT, Trimble TSIP, Zodiac, and
straight NMEA but it leaves out SiRF.

I don't see that the man page documents any formats at all.  What text
are you speaking of?  Would you quote it, please?  I want to make sure
we're not talking past each other.

Sure thing:


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.

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