1300 Henley Court
Pullman, WA 99163
509.334.6306
www.digilentinc.com
PmodGYRO™ Reference Manual
Revised April 12, 2016
This manual applies to the PmodGYRO rev. A
DOC#: 502-215
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 1 of 3
Overview
The PmodGYRO is a 3-axis gyroscope powered by the STMicroelectronics L3G4200D. By communicating with the
chip through SPI or I2C, users may configure the module to report angular momentum at a resolution of up to 2000
dps at an output rate up to 800Hz.
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:
The PmodGYRO.
Features include:
PmodGYRO™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 2 of 3
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
Slave
Start
Slave address and
Write bit
ACK
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.
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.
PmodGYRO™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 3 of 3
2.1 Pinout Description Table
Header J1
Header J2
Pin
Signal
Description
Pin
Signal
Description
Pin
Signal
Description
1
~CS
Chip Select
7
INT1
Interrupt 1
1,
5
SCL
Serial Clock
2
MOSI
Master-Out-Slave-
In
8
INT2
Interrupt 2
2,
6
SDA
Serial Data
3
MISO
Master-In-Slave-
Out
9
(NC)
Not Connected
3,
7
GND
Power Supply
Ground
4
SCLK
Serial Clock
10
(NC)
Not Connected
4,
8
VCC
Positive Power
Supply (3.3V)
5
GND
Power Supply
Ground
11
GND
Power Supply
Ground
6
VCC
Positive Power
Supply (3.3V)
12
VCC
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.