usb problems

[Gene Heskett]

On Sunday 12 October 2014 02:41:15 Nils Kassube did opine
And Gene did reply:
> Gene Heskett wrote:
> > I am in need of a tool that will effectively do a ping against a
> > specified USB port, a port I know there is something on the other end
> > of the cable and hub as I just had a printer do a test page over the
> > same cabling. Basically I want to send a $55 down the cable once a
> > second to a specified port, in thgius case /dev/ttyUSB1, for
> > oscilloscope troubleshooting, at least as long as trouble doesn't
> > shoot back... ;-)
> 
> If that /dev/ttyUSB1 device is a USB->serial converter, you could treat
> it like any terminal device. Therefore, you can use stty to disable the
> handshaking lines and set the desired speed (e.g. 100 Baud). Then echo
> the desired characters to the device:
> 
> stty -F /dev/ttyUSB1 clocal ospeed 100
stty -F /dev/ttyUSB1 clocal ospeed 115200
stty -F /dev/ttyUSB1 clocal ispeed 115200
while true;do echo -n "e" >/dev/ttyUSB1;sleep 1;done
> 
> You can cancel the loop with CTRL-C.
> 
> 
> Nils

This works, I can see the once a second red led flicker.  But when 
measured with the scope, the baud rate seems to be about 55800 (not 57600) 
unless that "e" is a 2 bits high, 2 bits low etc character.

Cheers, Gene Heskett
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