Issue
140 March 2002
Spy-Size
Event Logger
byJeff
Bachiochi
Tiny
Dancer
Dallas
Semiconductor, now owned by Maxim Integrated Circuits,
is well known for its mixed-signal products. Dallas’s
expertise includes excellence in time keeping and data
logging just to mention two. It seems inevitable that
these would be combined into a single device at some point,
but an 8-pin real-time event recorder? This deserves some
attention.
| Figure
1—This is all that’s necessary for a working logger
circuit. J4 connects to the RS-232-to-I2C circuit. |
The
DS1678 contains all of the elements (except for a battery)
of a 1025 event recorder. Note that it is an event that
causes a time stamp to be saved. No data is actually saved!
The data itself is the event. The device communicates
using an I2C interface. The schematic in Figure 1 demonstrates
how the DS1678 is used in this project (also see Photo
1.)
|
(Click here to enlarge)
|
Photo
1—The DS1678 circuit with a battery (upper right)
fits into the 1² × 2² plastic shell for a spy-sized
event logger. The RS-232-to-I2C circuit is on the
left. |
