On Sat, Mar 19, 2005 at 11:04:32AM -0500, Brian Perkins wrote: > So I've been having problems with my pl2303 adapter. > The symptom is that it will download data from my GPS only some of the > time. Upon closer examination, it appears that it will sometimes drop > the first character on a read. > > I have a bit more data on this now. > I got my hands on another pl2303 adapter, which does not exhibit this > problem. The problematic one is a "type 2" and the OK one is a "type 1" > > The good one works great with the GPS. > > For testing, I just shorted pins 2 and 3 on the adapter and ran a > testing procedure. > > I'm attaching a short script with he testing procedure. This procedure > causes the problem to occur _every_ time. The good adapter shows > foofoofoofoofoofoo > [pause] > foofoofoofoofoofoo > > and the bad one always shows > foofoofoofoofoofoo > [pause] > oofoofoofoofoofoo > > (note the dropped f) > > Also of note: I got an oops and looping vm messages when I didn't wait > one second after one of the fuser -k (see script below). > > You can see the results of these two scripts at > http://throb.netspace.org/~bperk/pl2303-type2.log (bad one) > http://throb.netspace.org/~bperk/pl2303-type1.log (good one) > > You can also see the diff -u good bad > http://throb.netspace.org/~bperk/diffgoodbad.log > > The testing script is at > http://throb.netspace.org/~bperk/serialtest > > but here it is also, with a few extra comments. > > > #!/bin/bash > > fuser -k /dev/ttyUSB0 > rm /tmp/tmplog # special log file for testing > service syslog restart > rmmod pl2303 > modprobe pl2303 debug=1 > > echo Please insert bad adapter, the hit enter > read foo > stty -F /dev/ttyUSB0 -echo -echoe -echok -echoctl -echoke -onlcr 57600 > > cat /dev/ttyUSB0 & > sleep 1; > echo 'foofoofoofoofoofoo' > /dev/ttyUSB0
_never_ use cat and echo with serial tty devices. They don't always work, as you have found out. Please use a tty based program, like minicom. If you can duplicate the problem with a .c program, or minicom, please let us know. thanks, greg k-h ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
