Digilent 410-215P User Manual
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Revision: August 3, 2011
Note: This document applies to Rev. A of the board.
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Overview
The PmodGYRO is a peripheral module
featuring the STMicroelectronics® L3G4200D
MEMS motion sensor. The L3G4200D
provides a three-axis digital output gyroscope
with built in temperature sensor.
Features include:
• Standard SPI and I2C™ interface
• 250/500/2000dps Selectable
Resolutions
• Two customizable interrupt pins
• Power-down and Sleep Mode
• User configurable signal filtering
Functional Description
The PmodGYRO uses a standard 12-pin
connection and communicates via SPI or I2C,
defaulting to I2C communication. A pull-up
resistor on the CS line keeps the device in I2C
mode unless the CS line is driven low by the
master device
Interface
When communicating with the device the
master must provide a register address and a
flag specifying whether the subsequent action
is a read or write. The actual transfer of data
follows this command. Through this method,
the user can either configure the device by
writing to specific control registers within the
device, or read back data from separate readonly registers.
Two interrupts directly map to pins available to
the user on connector J1 of the PmodGYRO.
The configuration of INT1, present on pin 7 of
J1, is entirely user customizable. The main use
of INT1 stems from high and low events on the
three axes about which the gyroscope
measures angular speed. By default, the INT1
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is disabled. The second interrupt, INT2, is
primarily used for data ready and FIFO
interrupts and maps to pin 8 on J1.
For more information about the control
registers, data collection, and interrupt settings
available for user configuration, see the data
sheet for the L3G4200D on the
STMicroelectronics® website.
SPI Communication
The SPI interface uses three or four signal
lines for communication depending on the
current configuration of the device. These are
Chip Select (CS), Serial Data In (SDI) or
simply Serial Data (SDA) in 3-wire SPI mode,
Serial Data Out (SDO), and Serial Clock
(SCL). The PmodGYRO defaults to the 4-wire
operating mode. In order to use the 3-wire
mode, a control register must be written to. For
more detailed SPI communication, refer to the
device data sheet.
Doc: 502-215 page 1 of 2
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PmodGYRO™ Reference Manual
Connector J1
– SPI Commun
ications
Pin Signal
Description
Connector J2
– I2C Communication
Pin Signal
Description
I2C Communication
The I2C standard uses two signal lines, I2C
data (SDA) and serial clock (SCL). The
device supports both standard, 100 kHz, and
fast, 400 kHz, serial clocks. In accordance
with I2C protocol, the L3G4200D has a device
specific 7-bit address used by the serial
master to communicate with multiple devices
on a data bus. The device uses the address
110100xb, where pin 3 on J1 (SDO/SA0)
defines the least-significant-bit (LSB). By
default, the LSB of the address while be ‘1’
due to a pull-up resistor on JP1 as shown by
the schematic available on the Digilent
website. While the default value is ‘1’, by
simply connecting pin 3 on J1 to the ground
rail the user can change the LSB to a ‘0’. This
user selectable bit enables two PmodGYROs
to be used on the same I2C bus. The data
sheet for the L3G4200D contains further
device specific I2C information.
www.digilentinc.com
1 CS Chip Select
2 SDA/SDI/
Serial Data In
SDO
3 SDO/SA0 Serial Data
Out/LSB of I2C
Device
Address
4 SCL/SPC Serial Clock
5 GND Power Supply
Ground
6 VCC Power Supply
(3.3V)
7 INT1 Programmable
Interrupt
8 INT2 Data
Ready/FIFO
Interrupt
9 NC Not
Connected
10 NC Not
Connected
11 GND Power Supply
Ground
12 VCC Power Supply
(3.3V)
®
1 & 2 SCL/SPC Serial Clock
3 & 4 SDA/SDI/
Serial Data
SDO
5 & 6 GND Power
Supply
Ground
7 & 8 VCC Power
Supply
(3.3V)
www.digilentinc.com Copyright Digilent, Inc. page 2 of 2
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