Page 270 - Making PIC Microcontroller Instruments and Controllers

AN ARTIFIGIAL HORIZON: A TABLE

SURFACE THAT STAYS LEVEL

Proiect 5

In this project, we will r€ad dle inputs fi]m a unique, inexpensive, nvo-axis gnvity sensor
and use them to control the horizontal posilion of a table.
we will use this very interesting and tiny electronic gravity serNor to build a table
that stays horizontal while the base of the table is disturbed (within about 20 degrees)
relative to the horizon. The sensor we will use is the Memsic 2125 dual-axis accelerom
eter This sensor is available ftom Parallax Inc. already mounted on a tiny boad with
6 pin. rhal are 0. I inche' on cenrers,
The following is Parallax Inc.'s infomation on this Memsic accelerometer:
"The
Memsic 2125 is a low cost, dultL-&ris themnl accelerometer cdpable of meas-
uriftB dJndmic acceleration (vibration) an l static accebrution (graitJJ) with a range
of !2 g. For i tegrution into existing appLicatians, the Memsic 2125 is electicall, com-
patible with other popular accelelomeers."
Key tearures of lhe Memsrc 2125 are.
Measues 0 to12 g on either axis;with a surpnsing rcsolution of less thai 7 mg. (This
means that if you weigh 200 lb, this sensor could detect a cbange of 0.5 lb in your weight
as affected by graviry.)

Fully temperature compensated over a 0"C to 70'C range

Simple pul(e ourpur ofg-force for \ and y axis
Analog output of temperaturc (T-Out pin)
Low cuffent operation: less than 4 mA al 5 volts dc

2G9