External GPS Receiver
Contents |
GPS
A nanote GPS powered is interesting step for developing new features for this pocket computer.
This page provides information about the first approach of hooking up a closed source GPS module to the Nanonote, there is an ongoing work about a GPS_Free_Stack too.
Software
Graphical
TangoGPS is an application that allow show maps at location that the GPS gives, it requires internet connection at first but maps can also be cached and transfer for offline browsing.
I loaded just for see if runs, and runs, take about 30 seconds to load and seems some small but not too much due screen size, it was in the openwrt firmware which uses frame-buffer.
I tested TangoGPS in JLime firmware witch runs a X Sever and load speed improves to the half compared to openwrt, and also key bindings like i (zoom in), o (zoom out) and arrows keys are working.
Background Daemon
Gpsd is the daemon that could run in background. A good idea is add it boot time to improve responde in getting fix position.
Gpsd try to guess what gps is wired to the nano, it can be hacked in a good way (by configure script) and allow fix values like speed and support for the protocol that the device just need (seems not needed at all).
For a testing environment i recommend run gpsd from ssh like this:
gpsd -nNG -D 10 /dev/ttyS0
Note the -G will allow you to run software like xgpsd in the computer side to debug things as well.
And the -D allow debug if the gpsd is really understanding/receiving gps information.
All this is already ported in openwrt and Jlime :)
Nanomap is other app designed for the Nanone wich is pending to be tested and compiled with gpsd cliet support.
Textbased
There are other console clients very usefull like an starting point.
cgps <=== basic position not fancy maps gpxlogger <=== logger for traces, very usefull for helping osm and other tracking applications.
Debugging
cat /dev/ttyS0 <=== just look ;) stty <=== to fix port speed and more stuff
Hardware
Closed source
- So i have for testing a SIM548 Module (GPS/GSM) in a board
- For Ya there are ideas for a u-blox 5 AMY GPS module
- RXM-GPS-SR (from tuxbrain)
Free Stack
- some front-end GPS RF ICs have open datasheets, for example SE4120L
- there are also open stack/software development to correlate GNSS raw data and provide a fix point but there is a missing
- data acquisition module (with libre schmatics !!) for chips like SE4120L and others from SiGE
Requirements
- Serial port working on stable uboot branch (TP4/TP5)
- You need wire TP4/TP5 terminals fro the nano [1]
- Confirm that power module can drive GPS with no side effects
Issues
- Issue related with the SIM548 module confirmed in both openwrt and Jlime firmware, also in two Ben boards
GPS works just when the TX pin from it is wired to the Nanonote RX But if RX is wired the transmission stoped :/, seems not be a power issue after tested with separate 3V3 power Is not gpsd, it also happen with picocom terminal and cat ;).All using a SiRF protocol.
I swiched to a second uart port in the gps module, it uses NMEA protocol and then work now.
Possible solutions comments http://en.qi-hardware.com/pipermail/developer/2010-July/003298.html
- Cant open /dev/ttyS0 using openwrt firmware
Edit:
/etc/inittab
And comment the line about ttyS0 that will solve the problem after next reboot
#ttyS0::askfirst:/bin/ash --login
Pictures
Static Tests
jlime menu
jlime tangogps
jlime more tangogps
openwrt
gps antenna
ben and sim548 board1
ben and sim548 board2
TPS4/TP5 soldering
3v3 and GND from ben board
SIM548 board top
SIM548 board gps module
SIM548 board and ben board
zooming 1
zooming 2
zooming 3
zooming 4
zooming 5
zooming 6
zooming 6
zooming 6
Moving Tests and Out Door
- IMG 1896.JPG
Video
http://vimeo.com/13144803 {{vimeo>13144803?medium}}
Pending upload in ogg
To do
- Arrange all this wires/boards in a better way and try outside (done)
- Compile or install nanonomap and check how it works (WIP)
- Get gpsd utils in openwrt (just gpsd now)
- Get a tiny/portable GPS with tiny Antena SMA comptible (Ideas?)
References
- http://www.tuxbrain.org/downloads/nanonote/gps/ other ready to test module (from tuxbrain)
- http://wiki.opdevel.com/WRT54GL/WRT548 current board with gps/gsm sim548/
- http://www.compile-it.com/simcom/SIM548/SIM548_HD_V1.01.pdf SIM458 data sheet (current work in progress module)
- http://www.tangogps.org/gps/cat/Documentation tangogps key bindings
- http://gpsd.berlios.de/ gpsd website
- http://wiki.openstreetmap.org/wiki/Making_Tracks_with_Homebrew-ware#Software_2 making tracks
