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author | Eric S. Raymond <esr@thyrsus.com> | 2015-02-22 10:44:04 -0500 |
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committer | Eric S. Raymond <esr@thyrsus.com> | 2015-02-22 10:44:04 -0500 |
commit | 9087ef9f3d930fb26861d042e8906120799954a6 (patch) | |
tree | c69ae83b59db6dbc1e536ee67f704bef29ca0314 /www/upstream-bugs.html | |
parent | 6cb7062e7ccb2a24ffbdd74662c021275b0df259 (diff) | |
download | gpsd-9087ef9f3d930fb26861d042e8906120799954a6.tar.gz |
Document the Bluetooth troubleshooting procedure.
Diffstat (limited to 'www/upstream-bugs.html')
-rw-r--r-- | www/upstream-bugs.html | 47 |
1 files changed, 34 insertions, 13 deletions
diff --git a/www/upstream-bugs.html b/www/upstream-bugs.html index 0fd47883..886280d5 100644 --- a/www/upstream-bugs.html +++ b/www/upstream-bugs.html @@ -126,19 +126,40 @@ baud rate so tcsetattr is never called.</p> <h2 id="bluetooth">Firmware problems in some Bluetooth and USB devices can hang them</h2> <p>The baudrate-hunting code in <code>gpsd</code> tickles a serious -firmware bug on some some Bluetooth devices, notably those shipped by -Holux and including the GPSlim-236. This bug may render these GPSes -catatonic. The problem seems to be that buggy firmware inside these -receivers doesn't necessarily keep the Bluetooth serial-port emulation -and the GPS chip talking at the same baud rate. This problem is not -unique to <code>gpsd</code> — Windows users are warned against using -SiRFdemo's "Synchronize Protocol/Baud Rate" option on Bluetooth devices.</p> +firmware bug on some some Bluetooth devices; these are flagged on our +<a href="hardware.html">Hardware</a> page. This bug may render these +GPSes catatonic. The problem seems to be that buggy firmware inside +these receivers doesn't necessarily keep the Bluetooth serial-port +emulation and the GPS chip talking at the same baud rate. This problem +is not unique to <code>gpsd</code> — Windows users are warned +against using SiRFdemo's "Synchronize Protocol/Baud Rate" option on +Bluetooth devices.</p> <p>If this happens, you can sometimes recover by repeatedly sending -reset messages using <code>gpsctl</code>. The only guaranteed fix is to -drain the battery backing up the GPS's settings; in extreme cases, you -may have to open the case and unsolder the backup battery so the chip -forgets its configuration settings.</p> +reset messages using <code>gpsctl</code>. Otherwise, power-cycling the +GPS The only guaranteed fix is to drain the battery backing up the +GPS's settings; in extreme cases, you may have to open the case and +unsolder the backup battery so the chip forgets its configuration +settings.</p> + +<p>To check whether you have this bug:</p> + +<ol> +<li><p>Reset your GPS to a usable state.</p></li> + +<li><p>Launch gpsd with the Bluetooth device on the command line and +the -b option to prevent autobauding.</p></li> + +<li><p>Observe it operating.</p></li> + +<li><p>Power down the device and terminate gpsd.</p></li> + +<li><p>Launch with -b again and see if it still works.</p></li> +</ol> + +<p>If you find the device comes up on the last step, then you know +that -b is an effective workaround and can finger bad Bluetooth +firmware as the cause of the problem.</p> <p>A separate bug with less severe symptoms afflicts some USB devices. The probe strings <tt>gpsd</tt> sends in order to determine device @@ -148,8 +169,8 @@ break up the probe writes into smaller pieces, interleaving them with the first few packet reads, so they are far less likely to trigger this bug.</p> -<p>Use the -b option of gpsd to prevent it from trying to reconfigure -your GPS; this will avoid both problems.</p> +<p>You can use the -b option of gpsd to prevent it from trying to +reconfigure your GPS; this will avoid both problems.</p> <h2 id="pl2303">Linux pl2303 driver on openwrt 2.4 kernel can hang when device is read at unexpected speed</h2> |