In 1983, Seiko released
the UC-2000 digital wristwatch.
It features a 40
character 5x7 dot alphanumeric LC display
(4 lines with 10
chars), 4 buttons and an inductive
transmission circuitry
that allows the communication
with a small keyboard
(UC-2100), a BASIC computer (UC-2200)
and an Apple-II computer
(UC-2301 Interface).
For it's time, it
was a technologically advanced and
very sophisticated
(and therefore expensive) design.
Compared to normal
watches, where all the electronics is
integrated in one
chip, the UC-2000 has 6 chips (5 CMOS
and 1 bipolar), 3
of them for the display alone.
I recently became
aware of this watch and was able to get
one, and I realized
that the UC-2000 may be the way to
make an old dream
of mine come true - building my own watch.
Since I am an electronics
engineer, I was not interested
in one of those expensive
mechanical marvels, I wanted my own
digital watch. But
you cannot go into a shop, buy standard
parts and build yourself
a wristwatch.
Then I found the
UC-2000.
I dissected one (see
here), and I think it is possible to
replace the computer
core while keeping case, display,
beeper, battery holder
and all the rest.
My goal is to build
a watch that does what I programmed
it to do when I push
the buttons, and that is as accurate
as can be achieved
with modern microcontroller technology.
I plan to replace
the 32kHz 4bit CPU with 7.5K ROM and
2K RAM with a modern
ultra low power microcontroller,
the MSP430F149
(16bit CPU, 60K FLASH, 2K RAM) made by TI.
This controller can
run on a 32kHz watch quartz, has internal
voltage and temperature
sensors and very sophisticated
clock and power management
systems. I will try to implement
software compensation
algorithms for temperature and
voltage drift to
improve accuracy.
First step: Find out how it works.
One watch has become
my object of study and experimentation:
a DATA-2000 that
was kindly donated to me by Foggy from the SCF.
A colleague, our company's specialist for
tricky soldering jobs,
completely 'wired' the watch (see
here) for me (Thanks Ulli!).
I then hooked it up to a logic analyzer
(see here).
After finding out where the display, the
buttons etc. are
connected, and how the communication works,
Ulli worked his
magic again, he removed the core module
(see here and here).
The empty 'mainboard' looks like
this.
Here is what I found out so far:
LCDisplay communication protocol
inductive communication protocol
I connected the 'brainless' watch to the
microcontroller
development system (see
here), and I mananged (after a few
days of experimentation) to talk to the
display (see here).
Next steps:
write the software
Final steps:
make a replacement core module with
the microcontroller,
put it in the watch
...and hope that it will work as
intended
