GYRO 3 CLICK
PID: MIKROE-3449 Weight: 18 g
Gyro 3 click is a three-axis gyroscope Click board™ that can sense motion over three
perpendicular axes. It is equipped with the I3G4250, a three-axis digital gyroscope. This
IC incorporates microelectromechanical sensing elements (MEMS), produced using a
proprietary CMOS micromachining technology. This technology allows for excellent
stability and linearity over temperature. The angular data is available in a 16-bit format,
along with 8-bit temperature data. Gyro 3 click can be used for angular speed up to
2000 degrees per second (dps), it features a FIFO buffer, two dedicated interrupt lines,
and on-chip data processing for optimized firmware development.
Gyro 3 click is supported by a mikroSDK compliant library, which includes functions that
simplify software development. This Click board™ comes as a fully tested product,
ready to be used on a system equipped with the mikroBUS™ socket.
The I3G4250 IC supports both I2C and SPI interfaces, which allows Gyro 3 click to be
interfaced with a wide range of different MCUs. Although it is very sensitive (down to
0.008 dps/LSB) it is very resistant to shock and has a non-linearity of only 0.2% of the
full-scale value (FS). These features make Gyro 3 click a perfect solution for the
development and testing of a wide range of applications which rely on an accurate
angular rate sensing. This includes gyro-stabilization for various types of robots, drones,
UAVs and RC vehicles, game controllers, orientation sensing, gesture-based HMI
applications, VR glasses, and similar types of applications.
HOW DOES IT WORK?
Gyro 3 click is based on the I3G4250, a three-axis digital gyroscope sensor IC,
by STMicroelectronics. This device is produced using a proprietary CMOS
micromachining technology, which results in a high level of integration, allowing very
good linearity over temperature, and increased output stability when no motion applied
(referred to as a zero-rate level in the I3G4250 datasheet). It also makes it resistant to
shocks, allowing it to be used for speeds up to 2000 dps. It supports signal conditioning
including low and high-pass filtering, as well as the threshold detection on each axis.
Typically, higher dps range results in lower sensitivity. Therefore, the I3G4250 allows to
dynamically select the full-scale range (FSR) value in several discrete steps: ±245,
±500, and ±2000 dps. This allows optimized performance for a given usage scenario.
For example, if used in applications with faster angle rates such as sports equipment
monitoring (golf club or tennis racket), a higher FSR might be required, at a cost of
lower sensitivity.
The MEMS output voltage is sampled by a high-accuracy 16-bit A/D converter, allowing
the output in 2’s complement format. As mentioned above, different FS ranges have
different sensitivity per LSB. Therefore, raw output values of the sensor will have to be
multiplied with the sensitivity to obtain the values in degrees per second (dps). These
values can be obtained from the I3G4250 datasheet, for every FS range, respectively.
There are two filters available on the I3G4250 sensor: an external low-pass (LP) filter,
and a digital high-pass (HP) filter with user-selectable cutoff frequency. Both of these
signals can be digitally selected and applied to an angular speed measurement,
allowing the developer to reduce the noise or fine-tune the sensitivity within a desired
bandwidth.
The I3G4250 device features a FIFO buffer, which in combination with a dedicated
interrupt line, allows firmware optimizations while reducing the power consumption of
the application as a result. The FIFO buffer has 32 slots, each 16-bit wide, used to store
output values. The I3G4250 device can be configured to use the FIFO buffer in three
different modes: Bypass mode, FIFO mode, and Stream mode. While the first mode
allows the developer to read the values directly from the output registers, two other
modes allow the utilization of the buffer. The FIFO mode will collect the data and stop
collecting until its read (or reset), while the Streaming mode will continuously fill the
buffer, discarding the oldest value.
One of the two interrupt lines is labeled as DRDY/INT2 on the schematic, and it is
routed to the mikroBUS™ AN pin (labeled as DI2). This line is used to report one of the
programmable FIFO events: watermark level is reached, FIFO buffer is empty, and
there is an overrun event on the FIFO buffer (FIFO is full). The pin can also be used to
report when there is a new data available at the output after the conversion period (data
ready). To find out which event exactly has occurred, the host MCU should read the
status of the respective flag bits from the STATUS register.
The second interrupt line is used to report when the programmed threshold is reached.
It is possible to detect events which are above or below a programmable threshold, and
trigger an interrupt on the INT1 pin, routed to the mikroBUS™ INT pin. By directing the
I3G4250 device to wait for a built-in timer to expire, a false triggering can be prevented.
To detect an interrupt source, the MCU can should read the status of the respective flag
bits from the INT1_SRC register.
Gyro 3 click offers two communication interfaces. It can be used with either I2C or SPI.
The onboard SMD jumpers labeled as COMM SEL allow switching between the two
interfaces. Note that all the jumpers have to be positioned either I2C or to SPI position.
When I2C interface is selected, an additional SMD jumper labeled as ADDR SEL
becomes available, determining the least significant bit of the I3G4250 slave I2C
address. The Click board™ should be interfaced only with MCUs that use logic levels of
3.3V.
SPECIFICATIONS
Type
Motion
Applications
It can be used to develop applications for gyro-stabilization of
different types of robots, drones, UAVs and RC vehicles, game
controllers, orientation sensing, gesture-based HMI applications,
VR glasses, and similar types of applications.
On-board
modules
I3G4250, a three-axis digital gyroscope sensor IC, by
STMicroelectronics.
Key Features
Advanced interrupt engine allows simplified firmware development
and better system-wide power consumption, very good reliability,
precision, and zero-level stability, signal conditioning in a form of
low and high-pass filtering, both SPI and I2C interface…
Interface
I2C,SPI
Input Voltage
3.3V
Click board
size
M (42.9 x 25.4 mm)
PINOUT DIAGRAM
This table shows how the pinout on Gyro 3 click corresponds to the pinout on the
mikroBUS™ socket (the latter shown in the two middle columns).
Notes
Pin
Pin
DI2
1
AN
PWM
16
NC
NC
2
RST
INT
15
INT
CS
3
CS
RX
14
NC
SPI Clock
SCK
4
SCK
TX
13
NC
SPI Data OUT
SDO
5
MISO
SCL
12
SCL
INT / Data Ready
SPI Chip Select
Notes
Interrupt
I2C Clock
SPI Data IN
SDI
6
MOSI
SDA
11
SDA
Power Supply
3.3V
7
3.3V
5V
10
NC
Ground
GND
8
GND
GND
9
GND
I2C Data
Ground
ONBOARD SETTINGS AND INDICATORS
Label
Name
Default
Description
PWR
PWR
-
JP1JP4
SEL COMM
Right
Communication interface selection: left position
SPI, right position I2C
JP5
I2C ADD
Right
I2C address LSB selection: left position 0, right
position 1
Power LED indicator
SOFTWARE SUPPORT
We provide a library for the Gyro 3 click on our LibStock page, as well as a demo
application (example), developed using MikroElektronika compilers. The demo can run
on all the main MikroElektronika development boards.
Library Description
Library contains:
functions for getting INT and AN pin states.
function for setting CS pin states.
functions for getting and setting register values.
function for getting temperature register value.
function for getting XYZ-Axes values.
function for setting basic device parameters.
function for getting status register value.
function for getting FIFO data level.
function for interrupt threshold values and interrupt wait time.
Key functions:
void gyro3_config( void ) - sets basic settings to device.
void gyro3_getStatus( uint8_t * status_register ) - gets value of status register (27h).
void gyro3_getAxes( float * x_axis, float * y_axis, float * z_axis, uint8_t
measurement_range ) - reads values from XYZ-Axes registers and converts them to degrees per
second value based on measurement range setting.
Examples description
The application is composed of the three sections :
System Initialization - systemInit() - Initializes I2C interface, LOG interface and GPIO pins.
Application Initialization - applicationInit() - Initializes I2C driver and basic device configuratoin.
Application Task - applicationTask() - Checks if new data is available on all three axes, If yes then
reads and logs their values.
void applicationTask( )
{
gyro3_getStatus( &status_register );
if ((status_register & _GYRO3_ZYX_NEW_DATA_MASK) == _GYRO3_ZYX_NEW_DATA_MASK)
{
gyro3_getAxes( &x_axis, &y_axis, &z_axis, _GYRO3_MEAS_RANGE_2000 );
mikrobus_logWrite( "rn>>>>>>>>>>>>>>>>>>>", _LOG_LINE );
FloatToStr( x_axis, text );
mikrobus_logWrite( "x_axis : ", _LOG_TEXT );
mikrobus_logWrite( text, _LOG_TEXT );
mikrobus_logWrite( degrees_per_second, _LOG_LINE );
FloatToStr( y_axis, text );
mikrobus_logWrite( "y_axis : ", _LOG_TEXT );
mikrobus_logWrite( text, _LOG_TEXT );
mikrobus_logWrite( degrees_per_second, _LOG_LINE );
FloatToStr( z_axis, text );
mikrobus_logWrite( "z_axis : ", _LOG_TEXT );
mikrobus_logWrite( text, _LOG_TEXT );
mikrobus_logWrite( degrees_per_second, _LOG_LINE );
mikrobus_logWrite( "