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brltty - Braille display driver for Linux/Unix…  more info»


README for the Alva Driver

Version 2.2 (March 4, 2004)


This driver is copyrighted under the GNU Public License. It is free software.
See the file 'LICENSE-GPL' for more details.

Supported Hardware

This driver is supposed to work with any Alva braille display from the ABT3
(3nn), Delphi (4nn), and Satellite (5nn) series. It recognizes the 320, 340,
34d, 380, 382, 38D, 420, 440, 44d, 480, 544, 544t, 570p, and 584p; other models
can be easily added. The serial and USB ports are supported; the Parallel port
is not. This driver even supports the old (single byte) protocol for ABT3nn
models. Keypad and spacepad support are not implemented since I don't have them
and have no idea regarding their use.

Since I have an ABT340, I've personally tested the driver on that model only,
with both the old (single byte) and the new (double byte) protocols. The
instructions provided in this file might, therefore, not necessarily be
accurate for all supported models.

If you want any information about Alva B.V. and its products, you should look
at the web site of the Alva Access Group [].

ABT Connection

This driver supports serial and USB communication only. Some parallel port
communication was previously supported, but, since that support was based on a
non-GPL compatible and binary only library, it has been removed.  When/if
someone can help with providing us with the proper protocol information, we'll
be pleased to write an open source parallel port driver in conformance with
BRLTTY's license.

With serial communication, the ABT serial port must be set to alva-mode
(the default); see the description of 'Local Mode' in the ABT manual. The ABT
serial port has the same connections as the standard 9-pin serial port of
an IBM PC. Therefore, a cable connecting the ABT with a PC must have the
following wires: 

9 pin (ABT)        9 pin (PC)   or    25 pin (PC)

1                  1                  8 (CD)
2                  3                  2 (TD)
3                  2                  3 (RD)
4                  6                  6 (DSR)
5                  5                  7 (GND)
6                  4                  20 (DTR)
7                  8                  5 (CTS)
8                  7                  4 (RTS)
9                  9                  22 (RI)

This kind of cable is called a "null modem" (or "cross over") cable. All
connectors are female D connectors.

NOTE: I experienced some problems using the serial port while the computer was
connected to the parallel port on the ABT. If BRLTTY seems to work but exhibits
strange behaviour, just make sure there's nothing plugged into the parallel
port connector. At least give it a try ... it might help.

Before Compiling

Firmware Version 

Look in the file braille.h for a section identified as "User Settings".  You
have to define ABT3_OLD_FIRMWARE to 1 (0 by default) if your firmware version
is older than 010495. To get your firmware version, simply turn your ABT on
while not connected to your computer. The last digits that will appear on the
braille display are the firmware version. If the wrong firmware version support
is compiled in, you won't have access to your ABT control keys. If you have a
firmware version dated 010495 or later, you normally don't have to edit
braille.h since support for the new firmware is the default.

ABT Model

Because new firmware is assumed, the terminal model is set to "autodetect" by
default. Specific model selection is optional with the new firmware version. If
you have the old firmware version use the line "#define MODEL" with either
ABT320, ABT340, ABT380, ABT34D or ABT38D.  ABT_AUTO is for autodetection (use
only with the new firmware version).

Port Specification

There are a number of ways to specify the port on the PC to which the display
is connected. Here's a summary, although you should check BRLTTY's manual for
all of the details.

The default port is the primary serial port (/dev/ttyS0 on Linux). If you'd
like your brltty executable to have its own unique default port then use the
--with-braille-device= option of the configure script in BRLTTY's top-level
directory at build-time. If you'd like your system to have its own unique
default port regardless of which brltty executable is being used then use the
braille-device directive of BRLTTY's configuration file (usually
"/etc/brltty.conf"). If you'd like to specify a specific port when invoking
brltty then use the -d (or --braille-device=) command line option.

For a serial port, specify "serial:/path/to/device". The "serial:" qualifier is
optional (for backward compatibility). If a relative path is given then it's
anchored at "/dev" (the usual place that devices are found on a Unix-based
system). The following device specifications all refer to the primary serial
port on Linux:


For a USB port, specify "usb:". BRLTTY will search for the first USB device
which matches the braille display driver being used. If this is inadequate,
e.g. if you have more than one USB braille display which require the same
driver, then you can refine the device specification by appending the serial
number of the display to it, e.g. "usb:12345".

Serial Port Settings

The serial port configuration is defined in the braille.h header file.

By default, the ABT communicates at 9600 baud. Although I've run it at a higher
rate, the possibility of getting communication errors increases. If you change
the rate in braille.h, you must also change it in the local menu of your ABT.

Running the Driver

Please refer to BRLTTY's documentation for instructions on compiling and
selecting the Alva driver. When BRLTTY starts, the driver should display on the
computer screen some copyright stuff, its current configuration (model and
firmware version), and the port being used. This information may be helpful if
nothing happens with the braille terminal. Remember that the ABT keys won't
work if you have the wrong firmware version set up (although some braille
should be displayed anyway). You may run BRLTTY even if no ABT is plugged into
the appropriate port. BRLTTY will wait for it.

Key Bindings

All the key definitions are listed in the files help*.txt. Each file
corresponds to an ABT model. For more information on the functions listed, see
the BRLTTY manual. Basic keys are nearly the same as with the DOS software. For
a quick start, enter the help screen by:

   For 3nn and 4nn models, press the PROG key.
   For 5nn models, press the left outer key of the right satellite keypad.

On the 5nn models, you can also enter interactive command learn mode by
pressing the right outer key of the right satellite keypad.

Some keys found on the ABT34D, ABT380, and ABT38D are not currently bound to
any functions (because I don't have those keys). However, it is pretty easy to
add them in the code. See the function brl_readCommand() and/or send me your

Status Cells

The first three cells are used for status information as with the DOS software,
except for the third one which has the following meanings:

	t = cursor tracking active
	f = screen is frozen
	a = the display is in attribute mode

All three status cells display "hlp" when the help screen is active, "lrn" when
interactive command learn mode is active, "prf" when the preferences menu is
active, and "inf" when info mode is active.

Some models have five status cells rather than three. On these, the last two
cells are currently not used.

Nicolas Pitre <>
March 4, 2004
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