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| author | Eric S. Raymond <esr@thyrsus.com> | 2004-09-24 16:47:00 +0000 |
|---|---|---|
| committer | Eric S. Raymond <esr@thyrsus.com> | 2004-09-24 16:47:00 +0000 |
| commit | 3fee78971e43abc6e5009c524aecfa891be35304 (patch) | |
| tree | 6c73fce6b13878face63b86cafdb4a88ea22b254 /TODO | |
| parent | 13b10b5c81c470fe2d363ec89ff277c936d418da (diff) | |
| download | gpsd-3fee78971e43abc6e5009c524aecfa891be35304.tar.gz | |
Updated documentation.
Diffstat (limited to 'TODO')
| -rw-r--r-- | TODO | 34 |
1 files changed, 31 insertions, 3 deletions
@@ -1,4 +1,6 @@ -* Do the research to figure out just what the heck is going on with status bits +* Things to do: + +** Do the research to figure out just what the heck is going on with status bits NMEA actually has *three* kinds of validity bits. Mode, status, and the Active/Void bit (some sources interpret 'V' as 'Navigation receiver warning'). @@ -29,13 +31,39 @@ Which of these override which other bits? I don't think status is ever nonzero when mode is zero. So status overrides mode. What other such relationships are there? -* Mine the contrib directory for good ideas +** Mine the contrib directory for good ideas There is code in there that can do some interesting tricks with SiRF-II chipsets. Lonnie Mendez is working on this. -* gpsd.py is unsatisfactory +** gpsd.py is unsatisfactory It only handles straight NMEA devices. It should be replaced by a Python extension built around libgps.a. +* Things not to do: + +** Crank the update rate up past 1 per second + +At 50km/h (31mi/h) that's only 13.8 meters change in position between updates. +Faster refresh might make sense for aviation applications, but not on foot +or in a car. + +** Try to autodetect USB devices + +Sigh. USB scanning won't work. + +The fundamental problem is that there is no GPS device class in the +USB standard. When you get device information about a GPS from the +USB subsystem, all you get is info on the USB-to-serial chipset it's +using. + +This means that GPSes are not distinguishable from other USB-to-serial +devices, in particular USB-to-RS232C adaptors. This is a crash +landing. We could live with the scanning code failing to detect a +GPS that's there, but we can't live with having it mis-identify +another USB device as a GPS. The least bad result from that would +be that the daemon opens and locks up the other device. + +This cannot be fixed, short of USB 1.1 growing a USB device type +and vendor firmare advertising it. |