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Re: [gpsd-users] GPS on Qualcomm MSM7xxx and MSM6xxx devices

From: Eric S. Raymond
Subject: Re: [gpsd-users] GPS on Qualcomm MSM7xxx and MSM6xxx devices
Date: Sun, 19 Jul 2015 17:59:13 -0400
User-agent: Mutt/1.5.23 (2014-03-12)

Stanislas Bertrand <address@hidden>:
> Hi Eric,
> You are right, i'm looking for some notification that would indicate that
> the device has stopped emitting data.
> Is there a way to configure the timeout time or to get the time elapsed
> since the last gps data ?

>From gps.h:

    timestamp_t online;         /* NZ if GPS is on line, 0 if not.
                                 * Note: gpsd clears this time when sentences
                                 * fail to show up within the GPS's normal
                                 * send cycle time. If the host-to-GPS
                                 * link is lossy enough to drop entire
                                 * sentences, this field will be
                                 * prone to false zero values.

> I have setup a GPSd and taken a look at the JSON output but I don't see
> anything about my device going silent.

You won't, either.  Dead air is dead air; gpsd can't tell the
difference between a device that is choosing not to send data and a
device that has crashed. Your application has to deduce that by
knowing that the device has a cycle time.

> Furthermore, is there a easy shell GPSd JSON interface to  communicate
> easily.
> I have used gpspipe -w to get the JSON output and connected to GPSd via
> telnet. Is there other means ?
> Can you send request to GPSd with gpspipe ?

No. In general, the set of requests you can make over the socket interface
it restricted for security reasons - if it were possible to ship arbitrary
control strings it would be too easy to DOS many devices, which might screw
up other applications warching the device.

What request do you want to send?
                <a href="";>Eric S. Raymond</a>

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