Eric Vittoz - IEEE

TECHNICAL LITERATURE
sensors, pressure sensors, featuring atto Farad detection
level (10 -18 F) and full self-test capability including
the MEMS part and interface. Sensor interface technology
was used also in the Swatch Touch family; hitting
the glass with the tip of the finger would set off
some function such as light up the dial, stop an alarm
of play a small game.
VIII. From SIM-Cards to Flash-based RISC
Microcontrollers
A. Flash Memory and Time-to-Market
In 1997, EM Microelectronic was looking for semiconductor
projects to be realized in more advanced
silicon processes than the ones it had in-house.
Smartcards seemed to be a promising application,
both because of the level of integration required and
because of the fast evolution pace in this market. An
initial SIM card market analysis revealed that the
major market share relied on ROM-memory chip versions,
implying a new chip for every application evolution.
Considering the decreasing time-to-market of
such products, EM Microelectronic took the approach
of developing SIM-Card (fig. 9) circuits with Flash
program memory. Such technology represented a significant
competitive advantage and helped the company
to reach a leading position in the worldwide
SIM-Card IC market.
If watch-making was the cause for EM Microelectronic
to develop its EEPROM technology, giving the
company an advantage for non-watch applications,
we can say that the smartcard industry gave the company
the impulse to introduce Flash memory technology,
which now in turn paves the way for other innovations
in watch-making.
From the microcontroller point of view, multifunctional
quartz watches followed a path similar to many
other mass-market microelectronics applications.
Originally the products were based on ASIC circuits,
implying a new IC for every new product or even
product version. With the µPUS and PUNCH cores
and a set of interface building blocks, the watch makers
introduced a more modular approach; but these
circuits were all ROM-based versions, meaning that
every software change required a new metal mask,
i.e., a new chip. If original watch ASICs were considered
non-programmable devices, ROM-based microcontrollers
were qualified as fab-programmable (i.e.,
programmable by the wafer foundry) devices. The
next natural evolution step was then to offer fieldprogrammable
devices to the watchmakers (i.e., ETA).
B. RISC Microcontroller Architecture in a Watch
In 1998, EM Microelectronic initiated the development
of its latest watch microcontroller generation
based on CSEM’s CoolRISC 8-bit core with, besides
the required typical watch interface building
blocks, the addition of Flash memory. The original
SIM card Flash memory could not simply be transferred
to a watch circuit. Programming voltage and
power consumption common to cell phone applications
were much too high for a wristwatch. The
technology had to be adapted; current Flash memory
for watch applications operates at a programming
voltage of 1.8V.
The CoolRISC microcontroller family is now in use
in Tissot’s technical watch family (latest T-Touch,
Silent-T models, Navigator 3000 (fig. 10)). Swatch
also uses it in the Swatch Fun Scuba (fig. 9) and
Swatch Fun Boarder models. The Fun Scuba is the
first Swatch with an automatic depth-meter which is
automatically activated when the watch is one
meter below the water surface. The hour hand displays
depth down to a maximum of 40 meter. The
minute hand shows the total dive time. Information
about a dive can be stored and viewed/replayed by
the diver at any time. Once out of the water, the
watch automatically switches back to display the
time, just like any other watch. The Fun Boarder is
a variation on the same theme: instead of a depthmeter,
it features an altimeter; the minutes hand
shows the height up to 995m, while the hours hand
shows the height per 1,000m.
Fig. 9: Flash memory developed for SIM-cards now used in
watch applications (Swatch Fun Scuba)
38 IEEE SSCS NEWS Summer 2008