ADIS16201 Analog Devices, Inc., ADIS16201 Datasheet - Page 29

• Manufacturer Part Number: ADIS16201
• Description: Programmable Dual-axis Inclinometer/accelerometer
• Manufacturer: Analog Devices, Inc.

APPLICATIONS
SERIAL PERIPHERAL INTERFACE (SPI)
The ADIS16201 integrates a hardware SPI on-chip. SPI is an
industry-standard synchronous serial interface that allows data
to be transmitted and received simultaneously, that is, full duplex
up to a maximum bit rate of 2.5 Mbps depending upon the
sample period selection. The SPI port is configured for slave
operation and consists of four pins.
DOUT
The data out pin (DOUT) is an output pin used to transmit
data out of the ADIS16201. The data is transmitted in a 16-bit
(2–byte) format, MSB first.
DIN
The data-in pin (DIN) is an input pin that is used for the
reception of data from the master. The data is received in a
16-bit (2-byte) format with the W/ R control bit and address
contained in the first data byte and the data contained within
the second data byte, MSB first.
SCLK
The serial clock pin (SCLK) is used to synchronize the data
being transmitted and received through the SCLK period.
Therefore, a 16-bit (2-byte) word is transmitted/received after
16 SCLK periods. The SCLK pin is configured as an input.
CS
In the ADIS16201 a transfer is initiated by the assertion of the
chip select pin ( CS ), which is an active-low signal. The SPI port
then transmits and receives data in 16-bit blocks until the
transfer is concluded by de-assertion of CS .
The control registers within the ADIS16201 are based upon a
16-bit (2-byte) format. Data is loaded in from the DIN pin of
the ADIS16201 on the rising edge of SCLK. This requires 16
serial clocks for every data transfer framed by the low period of
the CS line. The part operates in full duplex mode with the data
clocked out of the DOUT pin, likewise on the rising edge of the
SCLK. For each read command received, the corresponding
output data is clocked out of the DOUT pin during the
following cycle, as defined by the CS line.
OUTPUT RESPONSE
Figure 39 displays the typical output response for the
ADIS16201 for several gravitational measurement orientations.
This is a convenient plot for understanding the basic orientation
of the inertial sensor measurement axes.
Rev. A | Page 29 of 32
HARDWARE CONSIDERATIONS
The ADIS16201 can be operated from a single 3.3 V (3.0 V to
3.6 V) power supply. The ADIS16201 integrates two decoupling
capacitors that are 1 μF and 0.1 μF in value. For the local
operation of the ADIS16201, no additional power supply
decoupling capacitance is required.
However, if the system power supply presents a substantial
amount of noise, additional filtering can be required. If
additional capacitors are required, connect the ground terminal
of each of these capacitors directly to the underlying ground
plane. Finally, note that all analog and digital grounds should be
referenced to the same system ground reference point.
GROUNDING AND BOARD LAYOUT RECOMENDATIONS
Maintaining low impedance signal return paths can be very
critical in managing system-level noise effects. For best results,
use a single, continuous ground plane that is tied to each
ADIS16201 ground pin via short via and trace lengths. In
addition to maintaining a low-impedance ground structure,
routing the SPI signals away from any sensitive analog circuits,
such as the ADC and DACs (if they are in use), can help
mitigate system-level noise risks.
X_ACCL
Y_ACCL
NOTES
1. DATA SHOWN IN TWOS COMPLEMENT FORMAT.
1
OUT
OUT
= 0LSB
= –2162LSB
Figure 39. Output Response vs. Orientation
X_ACCL
Y_ACCL
X_ACCL
Y_ACCL
1
(Not to Scale)
BOTTOM
OUT
OUT
OUT
OUT
VIEW
= –2162LSB
= 0LSB
= +2162LSB
= 0LSB
1
X_ACCL
Y_ACCL
EARTH’S SURFACE
ADIS16201
OUT
OUT
= 0LSB
= +2162LSB
1