2010-002 Silicon Designs, Inc., 2010-002 Datasheet - Page 3

• Manufacturer Part Number: 2010-002
• Description: DIGITAL ACCELEROMETER MODULE
• Manufacturer: Silicon Designs, Inc.

SIGNAL DESCRIPTIONS
CLK (input): Reference clock input. This hysteresis threshold input must be driven by a 50% duty cycle square wave
CNT (output): Count output. A return-to-zero type digital pulse stream whose pulse width is equal to the input CLK logic
Pulses from the CNT output are meant to be accumulated in a hardware counter. Each pulse accumulation or sample,
reflects the average acceleration (change in velocity) over that interval. The sample period or “gate time” over which these
pulses are accumulated determines both the bandwidth and quantization of the measurement.
The first equation above shows that as the sample rate is reduced (i.e. a longer sample period), the quantization becomes
finer but bandwidth is reduced. Conversely, as the sample rate is increased, quantization becomes coarser but the
bandwidth of the measurement is increased. The second and third equations show how the CNT pulse frequency equates
to the applied g-force. When using a frequency counter to monitor the CNT output pulse rate, a counter with a DC coupled
input must be used. The CNT output is a return-to-zero signal whose duty cycle varies from zero to fifty percent, from minus
full scale to positive full scale acceleration. A frequency counter with an AC coupled input will provide an erroneous
reading as the duty cycle varies appreciably from fifty percent.
CABLE LENGTH CONSIDERATIONS
Cable lengths of up to 45 meters (150 feet) can be added to the model 2010's standard 1 meter cable when it is connected
to a Model 3901 Adapter Cable and is being used with a Model 3320 G G G G -L
be a longer version of the G G G G -L
between the CNT and CLK signals. 15 meter (50 foot) cable lengths of DB9 male to DB9 female flat extension cable are
available on special order.
web site:
Silicon Designs, Inc. ! 1445-NW Mall Street, Issaquah, WA 98027-5344 ! Phone: [phone] ! Fax: [phone]
signal. Factory Calibration is performed at 250 kHz but the 2210 will operate at frequencies as low as 100 kHz or as
high as 1 MHz.
high time. The CNT pulse rate increases with positive acceleration. The device experiences positive (+1g)
acceleration with its lid facing up in the earth’s gravitational field. This signal is meant to drive an up-counter directly.
www.silicondesigns.com
Quantization (g' s)
g
FORCE
f
CNT
=
=
g
f
CLK
SPAN
-L
-L
-L
=
OGGER






1
2
g
f
f
SPAN
+
CLK
CNT
f
g
TM
CLK
g
FORCE
•
SPAN
−
9 conductor flat cable instead of the 2010's round cable to reduce crosstalk
f
2
1
SR






Model
[page 3]
2010
-L
-L
-L
Where:
Digital Accelerometer Module
g
g
OGGER
FORCE
SPAN
f
f
1 g
f
CLK
CNT
SR
TM
=
=
=
=
=
=
. The extension cable must however,
2 * (
accelerometer clock rate in Hertz
9.807 m / s
acceleration in gravity units
full scale acceleration in g' s
pulse rate in pulses / sec
sample rate in Hertz
2
or 32.175ft / s
2
Sep 07
)