Texas Instruments calculators as programmable LANC devices
Jukka Aho
All Sony camcorders have a 2.5mm LANC editing connector jack.
It can be used for synchronized editing, remote controlling
the camcorder or even accessing hidden service mode features.
It is possible to control practically all camera functions
via the LANC connector.
On the other hand, Texas Instruments manufactures
programmable graphing calculators which are very popular
amongst high-schoolers and college students. (Chances are
that you or your children already own one.)
Part of the reason for their popularity is that people have
found intelligent ways to run their own machine language
programs on the calculators (while they were not originally
intended to be used that way). Thus, people have been able
to create their own machine language games and other
programs for their calculators.
Some of the more popular TI models are TI-85 and TI-86,
which are both based on a 8-bit Z80 microprocessor (the
rival of 6502 and 6510; a familiar CPU for anyone who was
into home computing in the early 80's). Both TI-85 and
TI-86 feature a link connector that can be used for
transferring programs, equations and other information
between similar calculators or calculator and a PC.
Surprisingly, both the physical LANC connector and the
voltages seem to be the same as found in TI-85/86 link
cable. As a matter of fact, a standard TI-85 link cable
works fine as a LANC cable and vice versa.
This opens up interesting possibilities.
Numerous programs that control the TI link connector
have already been made. It seems to be technically
possible to program TI-85/86 (or any of the other TI
calculators which feature the same connector) to
function as a LANC device. The LANC bus operates at
9600 bps, which incidentally is the same rate as the
TI link cable normally works, so the calculator should
be able to handle this.
There would be many useful purposes for this kind of hack:
- The calculator could act as a replacement for Sony's
RM-95 service remote, thus enabling the DV-in, CVBS-in
and S-Video-in recording functions and other hidden
functionality on those cameras that have had these
features disabled in the factory.
- The calculator could control an ordinary consumer
video camera in advanced ways. One could e.g. program
the calculator to instruct the camera to shot individual
frames, say, once a minute (to produce nice clips of
fast-moving clouds, flowers that open in the morning,
sunsets etc).
- The calculator could be used as a way to access
obscure camera controls more straightforward way.
For example, one could control focus, zoom and white
balance functions more accurately than with the manual
controls. (Sometimes there even isn't manual white
balance control in the camera while it responds to the
white balance commands through the LANC connector.)
- The calculator could be used as a preset memory (or
macro storage and playback device) for different camera
settings and procedures.
- The calculator could function as a record button (that
is missing from some models - or more specifically, not
implemented in their IR remotes) for recording material
into the camera from an outside source via the A/V
connectors.
Having this kind of program available would really make
TI-85/TI-86 a valuable tool for many home video enthusiasts
and even semi-professionals.
LANC-related links:
<http://www.sel.sony.com/SEL/consumer/handycam/other/faq.html#33>
<http://home.t-online.de/home/mb.koenig/lanc.htm>
<http://www-users.york.ac.uk/~adv3/lanc/lanc.htm>
<http://www.geocities.com/CapeCanaveral/Hangar/1104/features5.html>
<http://perso.libertysurf.fr/dvin/>
<http://www.lynxdv.co.uk/sites/lynxdv/pc95.asp>
<http://www.cis.tu-graz.ac.at/wb/dvin/>
Texas Instruments calculators related links:
<http://www.ticalc.org/>
<http://www.ti.com/calc/docs/graph.htm>
<http://www.ti.com/calc/docs/85.htm>
<http://www.ti.com/calc/docs/86.htm>
The ticalc.org site contains lots of programs, source code,
programming information, tools and emulators for the TI
calculators. It also hosts mailing lists for discussion
about calculator programming. If you happen to have Z80
programming skills, own a TI calculator and a LANC video
camera and are interested in this kind of project, that
would be a good place to start.
-- znark