AlexPGP's Corner

I went to check on Galina last night soon after hearing the ker-thunk of falling wood (this morning, I discovered a rather largish branch had been blown off a tree, landing about 20 feet from the bedroom corner) and found her sound asleep (I started to say "sawing wood," but somehow that would've been inappropriate, don't you think?). As she is a light sleeper, I felt I dared not risk trying to climb into bed while she was so occupied, so I retired back to my office and prepared to sleep on the couch there.

And somehow, got interested in seeing if my DeLorme Earthmate LT-20 USB GPS "puck" would work with some of the fairly sophisticated GPS software that's been developed for Linux. Ultimately, it'd be a match made in kernel-space if I could use the unit with the Eee for the long trip to Colorado.

My, but was that a big mistake.

Basically, after setting everyting up on proust, nothing happened when everything was set in motion (so to speak). So, I started to look around on the 'net to see what I could see...

From the Ubuntu forum on launchpad.net:

The GPS LT-20 (USB-id 1163:0200 DeLorme Publishing, Inc.) sends standard NMEA commands over the USB. After connecting the device, a node is created as expected:

( A well-presented summary of output from diagnostic programs... )

Because of this communication bug, neither gpsd nor gpsdrive can communicate with the Earthmate.

User SqRt7744 replied:

To get it to work I did the following:

( A pretty good description of how to solve the problem... )

all good -> lots out NMEA output.

For some reason, the suggested makefile didn't work. I kept getting a message to the effect that nothing could be done for 'default'. So, I noodled around for information about make, and found the following, which provided the keys to the kingdom:

( Explanatory material I found helpful... )

The command line I actually ended up using to compile the module in my setup on the Eee is this (invoked from the /usr/src/modules subdirectory):

make -C /usr/src/linux-source-2.6.22 \
    O=/lib/modules/2.6.22-14-generic/build \
    M=$PWD

Although for this to actually work, I needed to create a 'makefile' in the /usr/src/modules directory with the single line

obj-m := cypress_m8.o

Finally, by 1:30 am, everything compiled and installed properly. However, I was too tired to test this out last, um, night, so (um, later) this morning, while on a shopping run, I took the hardware with me and gave the whole shebang a whirl. The software worked like a champ. (Now - and I use the term figuratively, as I must finish the translation due tomorrow - I need to figure out how to use GpsDrive. All in good time.)

Other lessons learned from this solitary orgy of under-the-hood computer goodness:

• lsusb will show the device, among others
• lsmod will show the module is loaded, among others
• dmesg will show where the device is
  ([###] usb 1-1: De...ate USB converter now attached to ttyUSB0)
• If everything is working cat /dev/ttyUSB0 will start filling the screen with lines of data starting with, typically, $GPxxx.... Get out of this by typing Ctrl-C.
• GpsDrive isn't too smart (or I am as yet too dumb).
  Run gpsd /dev/ttyUSB0 before invoking it
• Once the daemon has been launched, you can telnet localhost 2947
  Then type 'r' and see what the daemon is receiving
• You can get a lot of detail from: cat /proc/bus/usb/devices:
  T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 6 Spd=12 MxCh= 0
  D: Ver= 1.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
  P: Vendor=1163 ProdID=0200 Rev= 0.01
  S: Manufacturer=DeLorme Publishing
  S: Product=DeLorme USB Earthmate
  C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=100mA
  I: If#= 0 Alt= 0 #EPs= 2 Cls=03(HID ) Sub=00 Prot=00 Driver=cypress
  E: Ad=81(I) Atr=03(Int.) MxPS= 32 Ivl=6ms
  E: Ad=02(O) Atr=03(Int.) MxPS= 32 Ivl=6ms
  (But frankly, I don't know what to do with it.)

That's about all. This had better now be well and truly out of my system. Now, on to finish the translation!

Cheers...