Gumstix

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GPS

Using a USB GPS receiver

Your serial GPS unit *probably* uses a PL2303 usb-to-serial device. In which case, you need to get the PL2303 kernel module:

root@gumstix-custom-verdex:~$ ipkg install kernel-module-pl2303

If that goes okay, should should have a /dev/ttyUSB0 device after you plug in your USB gps. Then install gpsd:

root@gumstix-custom-verdex:~$ ipkg install gpsd

If that goes okay, gpsd will be started but will probably be trying to look at one of the other serial devices on the gumstix board. You need to stop gpsd:

root@gumstix-custom-verdex:~$ /etc/init.d/gpsd stop
Shutting down gpsd: Terminated

and then edit /etc/default/gpsd to point to /dev/ttyUSB0:

# If you must specify a non-NMEA driver, uncomment and modify the next line
#GPSD_OPTS=
GPS_DEV="/dev/ttyUSB0"

Now restart gpsd:

root@gumstix-custom-verdex:~$ /etc/init.d/gpsd start
Starting gpsd: success

If all is well, you should be able to use gpspipe to view the NMEA data from your GPS device:

root@gumstix-custom-verdex:~$ gpspipe -r
GPSD,R=1
$GPGGA,154319,1234.1234,N,12345.1234,W,1,06,1.40,124.5,M,123.123,M,,*5C
$GPRMC,154319,A,1234.1234,N,12345.1234,W,0.2414,96.218,060909,,*01

PROBLEMS!

Networking

Was having a problem where the network eth0 would not get a DHCP lease, and would come up as half duplex with TX transmit but no RX receive. Read this and decided to try the reccomendation of putting paper between the boards:

http://www.nabble.com/Re%3A-Networking-Problems-Cropping-Up-w--NetWiFiuSD-p18660920.html

It works now!

Audio Sampling

I found that I cannot sample at anything higher than 11khz without a buffer overrun. Some reading suggests that this is a result of the XScale processor not having a Floating Point Unit (FPU). Did a google search and found this, where someone suggests some intel libraries for non-FPU sampling:

http://osdir.com/ml/audio.mp3.encoders/2005-04/msg00024.html

Downloaded the said libraries from here (Non-commercial Linux version) and will be giving it a try:

http://www.intel.com/cd/software/products/asmo-na/eng/302910.htm

Maybe this will help? http://softwarecommunity.intel.com/isn/Community/en-US/forums/thread/5484107.aspx

Wireless

Was having this error:

Error for wireless request "Set ESSID" (8B1A) :

SET failed on device wlan0 ; Connection refused.

For some reason, it likes it better if you set the key first and then try to associate with the ESSID:

iwconfig wlan0 key [1] 1234-5678-90
iwconfig wlan0 key open
iwconfig wlan0 essid Shuttle

Found that fix here: http://moblin.org/pipermail/dev/2008-February/001407.html

Power Management

Use this to turn on the standard power management for the wifi interface. There are a lot of options for this in iwconfig:

iwconfig wlan0 power on

Bluetooh Serial Connection

I created a configuration file for Kermit and a script to do the rfcomm bind in order to open an Bluetooth serial session to the gumsitx.

Kermit configuration file

set line /dev/rfcomm0
set carrier-watch off
set speed 115200
set file type bin
set reliable
fast
set flow-control none
set rec pack 4096
set send pack 4096
set window 5
set prefixing all

Bind (and connect) Script

#!/bin/bash
rfcomm release /dev/rfcomm0
rfcomm bind 0 00:80:37:2F:08:0C 1
kermit gumstix-kermit.cfg

This done using these instructions: http://docwiki.gumstix.org/index.php/LinuxBluetooth

Storage

By default the fstab entry for the MMC slot on my netwifistixwhatchamacallit did not have sync, thus I would have to unmount the MMC before turning off the gumstix:

# mmc/microSD slot
/dev/mmcblk0p1       /media/card          auto       defaults              0  0

So I added it. Now I can turn off my gumstix without having to worry about non-commited file writes:

# mmc/microSD slot
/dev/mmcblk0p1       /media/card          auto       defaults,sync              0  0
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