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PmodGYRO™ Reference Manual
Revised April 12, 2016
This manual applies to the PmodGYRO rev. A
Overview
The PmodGYRO is a 3-axis gyroscope powered by the STMicroelectronics L3G4200D. By communicating with the
chip through SPI or I
2
C, users may configure the module to report angular momentum at a resolution of up to 2000
dps at an output rate up to 800Hz.
Features include:
The PmodGYRO.
3-axis MEMS digital gyroscope with high shock
survivability
Get angular momentum data with user selectable
resolution (250/500/2000dps)
Two customizable interrupt pins
User configurable signal filtering
Power-down and Sleep modes
Small PCB size for flexible designs 1.0 in × 0.8 in
(2.5 cm × 2.0 cm)
12-pin Pmod port with SPI interface and
additional I²C interface
Library and example code available in
resource
center
1
Functional Description
The PmodGYRO utilizes
ST L3G4200D gyroscope
to provide motion sensing data on each of the three Cartesian
axes. Users may configure both the resolution and filtering options for the measured data.
2
Interfacing with the Pmod
The PmodGYRO communicates with the host board via the SPI or I²C protocols. By driving the Chip Select (CS) line
to a logic low voltage state, SPI mode is enabled. The first byte sent over SPI informs the on-board chip if a read or
write command is going to be issued, if the register address should be incremented after a particular command has
been completed, and the 5 bit address of the register that is to be written to.
An example timing diagram for SPI read and writes from the L3G4200D datasheet is provided below:
DOC#: 502-215
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Other product and company names mentioned may be trademarks of their respective owners.
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PmodGYRO™ Reference Manual
Figure 1. Timing diagram.
Correspondingly, if the CS line is left at a high voltage state by an internal pull-up resistor, the I²C mode of the
PmodGYRO is enabled. The on-board chip has two possible slave address in the form of 110100x where x is the
voltage state of the Master-In-Slave-Out (MISO) pin on the SPI header. After the slave address and the read or
write bit has been transmitted and the message was acknowledged, a 7-bit register address can then be
transmitted. The most significant bit (the first bit of the 8-bit of the transfer) indicates if multiple bytes of
information are to be transferred.
An example transfer scheme for a master device reading multiple bytes of data from the PmodGYRO is provided
below:
Master
Start
Slave address and
Write bit
Multi-byte bit and
register address
ACK
Restart
Slave address and read
bit
ACK
Data
ACK
Data
ACK
Data
NACK
Stop
Table 1. Example transfer scheme.
Slave
ACK
Data is recorded and stored within the registers of the L3G4200D in degrees per second (dps). Correspondingly, a
measured value of 360 dps is equivalent to 60 rpm. Users can retrieve data from the PmodGYRO by following the
provided code example.
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
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PmodGYRO™ Reference Manual
2.1
Pin
1
2
3
4
5
6
Pinout Description Table
Signal
~CS
MOSI
MISO
SCLK
GND
VCC
Description
Chip Select
Master-Out-Slave-
In
Master-In-Slave-
Out
Serial Clock
Power Supply
Ground
Positive Power
Supply (3.3V)
Header J1
Pin
7
8
9
10
11
12
Signal
INT1
INT2
(NC)
(NC)
GND
VCC
Description
Interrupt 1
Interrupt 2
Not Connected
Not Connected
Power Supply
Ground
Positive Power
Supply (3.3V)
Pin
1,
5
2,
6
3,
7
4,
8
Header J2
Signal Description
SCL
SDA
GND
VCC
Serial Clock
Serial Data
Power Supply
Ground
Positive Power
Supply (3.3V)
Table 2. Pinout description table.
Any external power applied to the PmodGYRO must be within 2.4V and 3.6V; however, it is recommended that
Pmod is operated at 3.3V.
3
Physical Dimensions
The pins on the pin header are spaced 100 mil apart. The PCB is 1 inch long on the sides parallel to the pins on the
pin header and 0.8 inches long on the sides perpendicular to the pin header.
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
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