[BRLTTY] usb to serial problems

[Dave Mielke]

[quoted lines by Daniel Dalton on 2008/04/26 at 14:08 +1000]

>When pluging my braille note into my box with a usb to serial (and an 
>adapter) (So it will connect since the port on the end of the cable is not 
>different so won't connect to the BN) I then plug the usb end into my usb 
>port.

One thing to watch for here is if you need a straight-through or a cross-over 
cable. These refer to how the data transmission and flow control wires are 
connected. A serial connection is designed around the concept of connecting a 
terminal to a modem. The terminal end uses some of the lines to transmit data 
and signal flow control to the modem, and the modem uses some other lines to 
transmit data and signal flow control to the terminal.

Usually (but not always) if the device has a male port then it's the terminal 
end and if it has a female port then it's the modem end. If, therefore, both 
your converter and your BrailleNote have the same type of port (probably both 
male) then you most likely need a cross-over cable.

Also, you should be sure that your cable has all nine lines rather than just 
five. The five-line cables don't support flow control.

>$ sudo dmesg | less
>
>The last two lines I see are:
>
>usb 1-1: new full speed USB device using uhci_hcd and address 13 usb 1-1: 
>configuration #1 chosen from 1 choice pl2303 1-1:1.0: ch341-uart converter 
>detected usb 1-1: ch341-uart converter now attached to ttyUSB1
>
>So I assume it is detected and run:
>brltty -b bn -d ttyUSB1

Yes, that's correct.

The fact that, as you reported within another post, you're getting "write 
error: no such device" is rather odd. My guess is that an error further back 
than what you posted might shed more light on what the underlying problem is. 
Please run brltty like this:

   brltty -b bn -d serial:ttyUSB1 -l debug -e 2>/path/to/brltty.log

Then post brltty.log so that we can have a look at it.

In case you're curious: "-l debug" means to log as much as posislb. "-e" means
to log to standard error rather than to syslog. "2>/path/to/brltty.log" means 
to redirect standard error to the specified file so that all the logs are 
isolated and all in one predictable place.

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