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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 01:17:31 -0500 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Alexander Carver <address@hidden>:
> Is it possible to send any SiRF command to a GPS via gpsd or can you
> only send certain commands already in the source code? I see the -x
> in gpsctl but it's not clear how to send SiRF messages (SiRF isn't
> one of the listed examples).
It's not possible to send general control messages from an ordinary
gpsd client. It is possible to do it via the gpsctl utility; you should
look into that.
The reason for this restriction is that the devices gosd manages are shared
resources. The capability to send unrestricyed control messages from a
client could be a tool with which to DOS other users.
> I specifically want to send message 133 (0x85) which toggles the
> DGPS source of the receiver. I've discovered that my receiver
> occasionally loses the SBAS satellite and won't recover it on its
> own. However, toggling the source from SBAS to NONE and then back
> to SBAS causes it to lock onto the satellite again.
>
> The message is seven bytes long:
>
> MsgID (1 byte unsigned), Source (1 byte unsigned), internal beacon
> frequency (4 bytes unsigned), internal beacon bitrate (1 byte
> unsigned)
>
> The last two are unused when selecting SBAS and are set to zero so
> turning off DGPS should use this message payload (hex spaced out to
> show message divisions):
>
> 85 00 00000000 00
>
> And turning it back on set to SBAS is:
>
> 85 01 00000000 00
Which SiRF is this? I could make this sequence part of the configuration
string set at device wakeup time; that way, if the device had lost the
satellite during a session, it would be re-acquired whenever the device
is reopened by another WATCH.
--
<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
- [gpsd-users] Sending SiRF commands to GPS receiver, Alexander Carver, 2012/02/23
- Re: [gpsd-users] Sending SiRF commands to GPS receiver,
Eric S. Raymond <=
- Re: [gpsd-users] Sending SiRF commands to GPS receiver, Alexander Carver, 2012/02/26
- Re: [gpsd-users] Sending SiRF commands to GPS receiver, Eric S. Raymond, 2012/02/26
- Re: [gpsd-users] Sending SiRF commands to GPS receiver, Alexander Carver, 2012/02/26
- Re: [gpsd-users] Sending SiRF commands to GPS receiver, Eric S. Raymond, 2012/02/26
- Re: [gpsd-users] Sending SiRF commands to GPS receiver, Alexander Carver, 2012/02/26
- Re: [gpsd-users] Sending SiRF commands to GPS receiver, Eric S. Raymond, 2012/02/26
- Re: [gpsd-users] Sending SiRF commands to GPS receiver, Alexander Carver, 2012/02/26