| KY Office for the Blind | |||
 |
|||
| KY Office for the Blind | |||
| |
|||
The Kentucky LCD Interface Project
This page contains the following sections:
Consumer Products Adapted with the LCD Interface
General Description of the LCD Interface
Installation and Operating Instructions for Telephones adapted with the LCD Interface
Click here to download the entire project documentation in a zipped file lcd.zip
Consumer Products Adapted with the LCD Interface
Below is a current listing of all consumer devices known to have been successfully accessed by the LCD Interface.
This list is continuously updated as additional products are
accessed. If you successfully interface to a product not on this list, please contact us
so we can add it to the list and inform others. Call, write, or email:
Kentucky Office for the Blind
P.O. Box 757
Frankfort, KY 40602
Phone 502-564-4754 or 800-321-6668
FAX 502-564-2951
(Last revised 11-18-98)
1) Yamaha QY10 Music Sequencer (16x1 LCD)
2) Yamaha MDF2 MIDI Data Filer (16x1 LCD)
3) Northern Telecom Meridian model M7324 telephone (16x2 LCD)
4) Yamaha Diskclavier DKW10 player piano control unit (16x2 LCD)
5) Furuno Global Positioning System Marine Navigation device GP-50 (16x4 LCD)
6) Kawaii K4 Music Synthesizer Keyboard
7) Tadiran EKT-321 Electronic Key Telephone (16x2 LCD)
8) Yamaha Diskclavier DKC100R player piano control unit (24x2 LCD)
9) Brother P-Touch Model PT-20/25 label making device (15x1 LCD)
10) NEC Telephone Model ETE-16D-2 (16x2 LCD)
11) AT&T Telephone Model 7406 (24x2 LCD)
12) Hitachi Telephone Model DT-5054A (40x2 LCD)
13) Executone Telephone Model N/D29K/D 82600 (16x4 LCD)
14) Rolm Telephone Model RP624SL (24x2 LCD)
The following devices have been examined and found not to be compatible with the LCD Interface.
1) Northern Telecom Meridian Model M2616 Telephone
2) Some newer models of the Meridian M7324 Telephone use a different LCD driver chip
and are not compatible
General Description of the LCD Interface
"LCD Interface" -- An access device for
individuals who are blind or visually impaired -- June 1993
INTRODUCTION
The trend in consumer and commercial electronics seems to be
one of increasing sophistication. Every year more and more
devices include text LCD's (Liquid Crystal Display) built
into their products. Devices such as telephones, fax
machines, photocopiers, bar code readers, music keyboards
and synthesizers, test instruments, modems, laser printers,
and probably tommorow's toasters use LCD's to convey
information to the user. This kind of user friendliness is
a tremendous advantage, if you can see it.
The LCD Interface shown on the attached schematic provides a
convenient and standardized means of accessing LCD's to
accomodate users who are blind or visually impaired. This
circuit applies to all products using a liquid crystal
character display module compatible with the Hitachi HD44780
LCD controller. This pervasive LCD controller has become
somewhat of a de facto standard found in many electronic
devices with text based LCD's. The LCD Interface described
here greatly enhances the feasibility of connecting existing
speech, braille, and character enlargement devices to LCD
based consumer products to provide access for users with
visual impairments.
GENERAL DESCRIPTION
The basic approach of this access method is to connect the
LCD Interface circuit specified on the attached schematic to
the consumer product's 14-pin bus used by the HD44780
compatible LCD controller. The LCD Interface can then
capture copies of all information written to the LCD. This
capture process occurs automatically in real time and does
not interrupt or in any way interfere with normal LCD
operation. The entire capture process is totally
transparent to the consumer product's normal operation.
The LCD Interface circuit would be a user owned device which
connects to consumer products. The complexity of this
connecting process could range from requiring a technician
to make a soldered connection inside the consumer product to
simply having the user plug a cable onto a built-in
externally accessible connector. The exact requirements
depend upon the level to which the consumer product
manufacturer has complied with the proposed LCD Interface
standard currently under consideration by the National
Federation of the Blind. The objective of that proposal is
to secure the voluntary cooperation of industry in adhering
to a standard during the design and manufacture of all LCD
text based consumer products. Such a commitment would be a
tremendous aid in providing access for users with visual
impairments.
Once captured, the LCD data can be processed by the
interface and sent to the on-board parallel or serial output
ports. From there, many existing speech, braille, and
character enlargement devices could be employed to present
the LCD information to the user. By customizing the
controlling program on the LCD Interface, each consumer
product could have its LCD contents uniquely interpreted and
then output under efficient user control to commonly
available speech, braille, or screen enlargement
peripherals.
TYPICAL APPLICATIONS
A common application of the LCD Interface would be to use
the serial or parallel ports to directly drive any one of
several speech synthesizers currently on the market. One or
more user pushbuttons are monitored by the LCD Interface
firmware to allow user control of speech output, such as
"speak line one" or "speak line two". The LCD Interface
firmware would be designed to fit the consumer product's
operation in whatever way necessary to maximize the
efficiency of using speech output.
Two such cases recently implemented involve a totally blind
person working as an emergency dispatch officer and another
partially sighted person working as a telephone
receptionist. The LCD Interface provides access to the LCD
of their Northern Telecom Meridian Telephone model M7324.
It supports connection of a speech synthesizer to it's
parallel port, or connection of a personal computer running
screen enlargement and communications software to it's
serial port.
Basically, the interface watches for one of two user
pushbutton requests to speak the captured display. It also
watches for any change in the LCD text and if detected,
sends both LCD text lines to the serial port for display on
a computer running screen enlargement software. This
results in two means of access, speech for a totally blind
individual and screen enlargement for a partially sighted
person. Other unique methods of control are possible and
need only to be coded into this controlling program to best
serve the user's needs.
A similar application would be to use the LCD Interface to
drive a refreshable braille display device or braille
printer. The LCD Interface firmware could be programmed to
cause an update whenever the LCD text changed. This would
result in an automatic real time braille copy of the LCD
contents without the need for user intervention. Again, the
LCD Interface firmware can be tailored to best fit the
consumer product and the user's needs.
Another recent case aided a professional musician who is
blind by connecting an LCD Interface to a Yamaha QY10 Music
Sequencer to allow speaking of its one-line 16 character
LCD. Also the Yamaha MDF2 MIDI diskette data filer was
similarly adapted. Many musicians who are blind or visually
impaired are finding it increasingly difficult to use
today's sophisticated music gear. Much of the music
production and recording equipment contain text LCD's.
Musicians and composers who are sight impaired may find
themselves becoming less competitive with their sighted
peers who can take immediate advantage of the latest
electronic music equipment. This LCD Interface should allow
visually impaired individuals in the music business a more
equal access to music technology.
One of the most universal applications is to use the LCD
interface to simply pass on to a personal computer via the
serial port all captured LCD instructions unprocessed. A
user written program on the personal computer could then
process those instructions and send the resulting text to
speech, braille, or screen enlargement devices likely to be
already installed on their computer. This approach has the
advantage of allowing users to add and modify their own
support for additional LCD based consumer products without
the need for burning new firmware into the LCD Interface.
These support programs could be written and shared by users
within the blind community to support a wide variety of
consumer products. The LCD Interface would simply be a
means of capturing all LCD instructions and data into the
personal computer for processing.
HARDWARE DESCRIPTION AND OPTIONS
Connection is made to the consumer product's LCD by either
J5 or J6 depending on whether the LCD Interface is embedded
into the consumer product or housed externally. (J5 also
doubles as a connection point to a logic analyzer for
testing). This connection allows the FIFO memory buffers U3
and U4 to capture copies of all instructions sent to the
LCD. This capture process happens automatically in real
time without interrupting or interferring in any way with
normal operation of the consumer product's LCD.
Three of U5's gates are used to inhibit capture of the
"read
busy flag" instruction which carries no useful information
and would only tend to fill up the FIFO memory buffer with
useless instructions. LCD instructions need buffering by
the FIFO memory because they occur much faster than they can
be processed for speech or braille output.
Signal -DAV indicates to the 8749 microcomputer chip U1 that
an LCD instruction is captured and awaiting processing.
Since the LCD instructions are ten bits each, U1 must read
the next location in both U3 (using signal -RDL) and U4
(using signal -RDH) into port P1 to retrieve the next LCD
instruction. (Reference the Hitachi data book for details
about each of the eleven instructions defined for the
HD44780 LCD controller driver.)
Instructions are then processed according to the algorithm
determined by the programmer of the LCD Interface.
Generally, this involves maintaining a real time copy of the
LCD's 80 character RAM bytes in the 8749's on-board RAM.
Depending on the algorithm and the state of the user
pushbuttons S2 and S3, the interface may then send ASCII
text out either or both the serial and parallel ports for
speaking, brailling, or displaying in large characters.
The parallel output port emulates a personal computer
parallel printer port including the 25-pin female D-sub
connector. Any speech or braille device that can be driven
by the parallel printer port of an IBM PC compatible
computer should be able to be driven equally as well by the
LCD Interface's parallel output port. Handshaking occurs
automatically as it normally would through the -STROBE and
BUSY lines of the parallel port. For applications where an
LCD Interface and speech board (such as the Walk 'n Talk)
can be embedded within the consumer product, J3 can connect
directly to the speech circuit's parallel port using a
ribbon cable with socket connectors thereby saving the cost
of D-sub connectors and external cables.
The serial output port emulates the output portion of a
personal computer RS232C serial port including the 9-pin
male D-sub connector. Any speech or braille device that can
be driven by the serial port of an IBM PC compatible
computer should be able to be driven equally as well by the
LCD Interface's serial output port. Normally, no
handshaking or receive data is supported by the LCD
Interface. The handshake output lines DTR and CTS from the
LCD Interface are held permanently active for those
peripherals that might require them. It is assumed that all
speech and braille peripherals can sufficiently buffer the
small amounts of text that will be sent from an LCD module
having a maximum possible display size of 80 characters.
Two spare RS232C receivers are available within U6 for
special applications that might need them. Bypassing U6
would allow TTL level serial communications if needed. By
making minor modifications to the LCD Interface board, some
degree of flexibility is available for receiving serial data
and implementing a user defined handshaking scheme.
Appropriate board modifications and connections to spare I/O
lines on U1 would have to be made and firmware installed to
support such a customization, but the flexibility is there.
Signal TXD carries serial data to the RS232 level converter
U6 at a preset baud rate of 9600, 8 data bits, and no
parity. (Stop bit length can be any value since there is an
inherent processing delay after every character transmitted
anyway). These serial parameters are fixed by the timing
inherent within the serial port firmware routines and the
crystal frequency value. Fixed parameters reduce hardware
costs, free users from having to set DIP switches (an
important consideration for users with visual impairments),
and should offer little restriction since most speech and
braille peripherals allow adjustment of these parameters.
For added flexibility, four spare input/output lines P20,
P21, P22, and P23 are available for use with a particular
consumer product that might need them. Possible uses
include additional user input switches, monitoring of
consumer product visual indicators like LED's or lamps,
activating external audio or tactile indicators, etc. If
more than four lines are needed, the optional 8243 I/O
Expander chip U7 is easily installed to instantly provide a
total of 16 input/output lines. Of course, the programmer
must write code into the 8749's firmware to support any such
additional I/O activity.
J1 can optionally provide power to a speech board (such as a
Walk 'n Talk) in an embedded environment thereby using one
power source and power switch to serve both the LCD
Interface and the speech synthesizer. Some cost savings can
be realized by omitting U6, C6, C7, C8, C9, and J7 in
embedded environments where serial data output is not
needed.
DISABILITY AWARENESS
The recently passed Americans with Disabilities Act (ADA)
has spawned a new era of public awareness of the many ways
in which individuals with disabilities are discriminated
against, often unintentionally. Projects like the one
described here are custom retrofits attempting to overcome
the information denial inherent in products designed without
regard for sight impaired users. Custom modifications are
expensive. Most individuals cannot afford the engineering
costs involved in creating such specialized access
interfaces. Often, their only recourse is rehabilitation
agencies who use public funds to provide technical services
to individuals who qualify for assistance. But many don't
qualify and funds are limited for those that do.
The LCD Interface Standard proposal currently under
consideration by the National Federation of the Blind issues
a challenge to the manufacturing industry. That is,
throughout the design phase of a new product, to maintain an
awareness of how that product might be used by individuals
with disabilities. Get external input. Get input from
persons who are blind and currently using similar products.
Contact disability advocacy groups and rehabilitation
agencies to avoid re-inventing the wheel. Obviously,
manufacturing considerations and cost will greatly restrict
what can be done to accommodate an admittedly small market.
But often times a little forethought during the design stage
can result in an extremely useful feature or access method
for users with disabilities at a minimal increase in cost.
No one wants to increase the cost of products for all people
just to accommodate a few. But often, it's a matter of
awareness, not cost. A little advance planning could make
future products much easier to adapt for users with
disabilities. Hopefully, the availability of standard
interface devices, like this LCD Interface, will foster a
greater awareness and support within industry for those
users with special needs.
Kentucky Office for the Blind
P.O. Box 757
Frankfort, Kentucky 40602-0757
800-321-6668, 502-564-4754, FAX 502-564-2951, TDD 502-564-2929
Installation and Operating Instructions
Adapting Telephones with the Kentucky LCD Interface
(using a Walk 'n Talk Speech Synthesizer or IEE Large Character Display)
Telephones adapted as of 11-18-98:
1) Northern Telecom Meridian Model M7324
2) AT&T Model 7406
3) Tadrian Model EKT-321
4) NEC Model ETE-16D-2
5) Hitachi Model DT-5054A
6) Executone Model N/D29K/D 82600
7) Rolm Model RP624SL
Your's could be next if it uses a Hitachi HD44780 type LCD driver chip.
The following telephones have been examined and found NOT
to be compatible with the LCD Interface.
1) Northern Telecom Meridian Model M2616 Telephone
2) Some newer models of the Meridian M7324 Telephone use a different LCD driver chip
and are not compatible
Installation Instructions
(These descriptions assume use of the standard firmware. Customized firmware will usually result in special instructions.)
1) Connect the AC/DC power adapters. The power adapters are labeled. Connect one adapter plug to the LCD Interface power jack. Connect the other adapter plug to the Walk 'n Talk Speech Synthesizer power jack. They are not interchangeable even though either plug will fit either jack. Plug both adapters into live 120VAC outlets. With the IEE Large Character Display configuration, there is only one power adapter.
2) Connect the parallel port ribbon cable. For the speech configuration, connect the LCD Interface 25-pin parallel output port to the Walk 'n Talk speech synthesizer using the 25-conductor wide ribbon cable. Each plug is unique and can only be inserted one way. Through this parallel port connection, text will only be spoken when the user requests it by pressing a push button on the LCD Interface. For the IEE Large Character Display configuration, skip this step.
3) Connect the serial port ribbon cable (maybe). In addition to push button requests to speak, if you want the system to also speak automatically whenever any text changes on the telephone LCD panel, then also connect the 9-conductor narrow ribbon cable. It goes from the LCD Interface 9-pin serial output port to the Walk 'n Talk speech synthesizer 9-pin serial input port. The cable will only fit one way. Note that for many environments, this connection may result in too much unwanted talking. For example, if the phone LCD displays time, it will announce the date and time at every minute (or second) change. You can try it and then disconnect the cable later if desired. This "automatic" sending of text using the serial port is how the IEE Large Character Display configuration works, although no cables are needed since the IEE display and LCD interface are integrated into the same box. Other configurations using this serial port are possible, such as sending text to a pc running a terminal program (like ProComm) and screen enlargement software (like ZoomText) resulting in a real time automatic "mirror" of the telephone's display as large letters on the computer monitor. (Maybe we can find a use for those old pc’s…)
4) Connect the telephone ribbon cable. Connect the LCD Interface to the telephone using the 14-conductor ribbon cable with 15-pin male D-sub connectors on each end. Either end of the cable will plug onto either device.
5) Turn on the power switches. Turn on the LCD Interface by moving the toggle switch toward the power plug. For speech users, turn on the speech box volume/on/off thumbwheel control. The unit should say "ready". Both units may remain connected and powered on continuously, even overnight when not in use.
Operating Instructions
(These operating instructions apply only to speech users. Operation of the IEE Large Character Display is automatic.)
1) Push a button to speak the phone display. There are two push buttons on the LCD Interface. One push button speaks line #1 of the telephone LCD panel. The other push button speaks line #2. If a line is blank, no speech will occur. Simply push a button at any time to hear the text on that line. Holding a push button down for more than one-half second will cause the unit to spell out the text on the LCD panel. This is occasionally useful when the spoken text is unable to be understood. If you have the serial cable connected, the system will also speak automatically whenever the text on the telephone display changes. For phones with four lines on the LCD, the LCD interface will have four pushbuttons and customized software to speak each of the four lines.
2) Set the speech volume control. The Walk 'n Talk Speech Synthesizer has an on/off/volume thumbwheel control to set volume level. It also has a mono headphone jack which mutes the internal speaker when a headset is plugged in. If you use a stereo headset, you will need a stereo-to-mono adapter to have sound in both earpieces.
Troubleshooting
1) Is the telephone LCD panel displaying text? To hear speech, the text line selected must be actually displaying text when you press the corresponding push button. Blank lines and spaces are not spoken. Perform a function on the phone which results in text displayed on the LCD, then press a pushbutton to speak it. If text is never displayed on the telephone LCD, disconnect the LCD Interface ribbon cable from the phone. If there is still no text displayed, unplug the incoming phone line from the back of the phone, wait five seconds, then reconnect. This should reset the telephone within a couple of minutes. If you still cannot make text appear on the telephone’s LCD panel, contact your telephone support personnel. (Then, they may want to call us.)
2) Check all cables. They must be seated completely. Disconnect and reconnect if suspect.
3) Check power supplies. Make sure each device is getting power from the correct AC/DC adapter. No power to the LCD Interface may even prevent the LCD panel on the telephone from working properly. Verify that the telephone’s LCD panel is working properly.
4) Reset the LCD Interface. Turn the LCD Interface power toggle switch off for five seconds, then back on to reset the device. "On" is toward the power plug.
5) Reset the speech box. Turn the Walk 'n Talk thumbwheel control off, then on. It should say "ready".
6) If it still doesn't work, take the day off. Or, call the Kentucky Office for the Blind.
Kentucky
Office for the Blind
P.O. Box 757 209 St. Clair Street Frankfort,
Kentucky 40602-0757 USA
Phone (Toll Free): 800-321-6668 or 877-592-5463
Phone: 502-564-4754
Fax: 502-564-2951
TDD: 502-564-2929
Website Administrator -- blind@ky.gov
Home
| Administration
| Consumer Services
| Employer Services
| What's New
| Search
Disclaimer
Statement | Privacy Notice | Individuals
with Disabilities |
Comments
This page was last updated on April 4, 2006