HOBBYEAGLE A3 PRO V2 User manual

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User Manual
V1.0 Jun, 2021 Revision
Thank you for purchasing our products. A3 Pro V2 is a high-performance and functional 6-axis gyro
and stabilizer designed for R/C airplanes. In order for you to make the best use of your gyro and to
fly safely, please read this instruction manual carefully and set up the device as described below.
IMPORTANT NOTES
Radio controlled (R/C) models are not toys! The propellers rotate at high speed and pose
potential risk. They may cause severe injury due to improper usage. It is necessary to observe
common safety rules for R/C models and the local law. Read the following instructions
thoroughly before the first use of your gyros and setup the gyro carefully according to this
manual. We also recommend that you seek the assistance of an experienced pilot before
attempting to fly with our gyros for the first time.
After power on, A3 Pro V2 needs to perform an accurate gyroscope calibration, keep the
airplane stationary after power on and wait while the LED flashes blue. The LED will stay solid
blue if a slight movement is detected and the calibration will not start until you stop moving the
airplane, however, making the airplane level is NOT required during the initialization.
A stick centering is also required following the gyroscope calibration. Always put all the sticks
center (the throttle stick in the lowest position) before power on the airplane, and do not move
the sticks until the initialization is done.
Make sure to check the gyro direction of Aileron, Elevator and Rudder channels after installation
and always perform a test of them before each flight. An opposite reaction of the gyro could
lead to losing control or even crash!
It is recommended to use the supplied 3300uF/16V capacitor to get a more stable and secure
working voltage for the gyro. The capacitor can be plugged onto any one of the free connectors
of the gyro or receiver.

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INSTALLATION
NOTES
Never use the hot-melt glue or nylon ties to fix the gyro onto the airplane!
You need only one piece of the tapes each time, a soft or thick mounting may probably impact
the performance of the gyro.
The gyro is a sensing device, please make enough space around it and keep as far away from
other electronic devices or wires as possible.
Mounting Orientation
Use one of the supplied double-sided tape to attach the gyro to your airplane firmly. For best performance,
the gyro should be mounted as close to the C.G. as possible, and the housing edges must be aligned
exactly parallel to all three rotation axes of the plane. The gyro can be attached flat or upright, and even
upside down, however, you have to ensure the arrow on the sticker always point to the heading direction,
otherwise the gyro will not work normally in ANGLE, LEVEL and HOVER modes.
① Flat, face up ② Flat, face down
③ Upright, button up ④ Upright Inverted, button down

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CONNECTION
Standard PWM Receiver connection
NOTES
[MODE] is used for flight mode switching of the gyro, connect it to a 3-way switch channel of
the receiver to switch the flight mode in flight.
[Serial RX/G] is used for remote master gain adjusting, connect it to a proportional channel of
a volume or slide lever of the transmitter to tune the master gain in flight.
The ESC or throttle servo is connected to the throttle channel of the receiver directly without
passing through the gyro.
Pay attention to the polarity of the plugs. The orange signal line must always be on the top and
the brown on the bottom.
Single-line Receiver Connection
A3 Pro V2 supports PPM and multi-protocol digital serial receivers which allows you to connect the gyro
to the receiver with one single wire. When using a specific type of these receivers the appropriate type of
receiver channel allocation will be preset in the A3 Pro V2. Please refer to the table below and check if

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your radio transmits the channels in the correct order. If this is not the case, you have to change the
channel mapping in the Receiver Menu. If you use a standard PWM receiver with standard wiring layout
the channel mapping does not apply. When A3 Pro V2 is operating in single line receiver mode, the [THR
Out/AIL] can be used as the throttle output channel for the ESC or the throttle servo if a mini receiver is
being used which has no additional output connectors.
Serial Receiver Protocols Supported: Default Channel Mapping
 PPM Receiver
Futaba S.Bus (compatible with FrSky SBUS, RadioLink
SBUS and WFLY WBUS)
Spektrum DSM/DSMX 1024 Satellite Receiver
Spektrum DSM/DSMX 2048 Satellite Receiver
Spektrum SRXL
Multiplex SRXL / JR XBUS Mode B
Graupner SUMD
FlySky iBus
NOTES
Please note that the remote master gain channel is disabled in single line mode as default.
Assign a channel number for gain channel in Receiver Menu to activate this feature if needed.
Pay attention to the polarity of the plugs. The orange signal line must always be on the top and
the brown on the bottom.
You will need to purchase an optional adapter if you are using a Spektrum satellite receiver.
Function
Channel Assignment
Aileron
Channel 1
Elevator
Channel 2
Throttle
Channel 3
Rudder
Channel 4
Flight Mode
Channel 5
Master Gain
None

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FLIGHT MODES
A3 Pro V2 provides 6 flight modes which can be switched by a 3-position switch of the transmitter during
flight. The factory default mode allocation of the switch is OFF - NORMAL - LEVEL. You can change the
settings in the Setup Menu according to your needs. The color of the LED shows the current flight mode
of the gyro while in use.
Colors of the LED for flight modes
Solid Red
GYRO OFF Mode
Solid Blue
NORMAL Mode
Blue, Flashing
LOCK Mode
Solid Violet
ANGLE Mode
Violet, Flashing
LEVEL Mode
Violet, Fast Flashing
HOVER Mode
1. GYRO OFF Mode
When operating in GYRO OFF mode the gyro will be deactivated completely, and the airplane will be
completely under the control of your transmitter as it was before installing the gyro. This mode is usually
used for testing purpose only.
2. NORMAL Mode
The NORMAL mode, also known as the ‘Rate mode’, is the most basic function of the gyro. It works
based on the rotation rate control of each axis of the airplane. When operating in this mode, the gyro will
only correct currently occurring rotational movements, a momentary reaction will be applied to the servos
when the airplane rotating on corresponding axis, after rotation the servos will move back to their neutral
position as soon as the airplane standing still immediately. The NORMAL mode can be used with nearly
any size and type of airplanes. It can effectively improve the stability and precision of the airplane and
reduce the stall point specially.
3. LOCK Mode
The LOCK mode is also known as the ‘Attitude Lock mode’, ‘3D mode’ or ‘AVCS mode’. Different from
NORMAL mode, the gyro will perform a permanent correction for rotational movements on each axis
constantly. That is when you release the sticks the airplane will stop and lock its current position
immediately. This mode is well suited for practicing basic 3D maneuvers such as hovering or knife edge.
Since it can help you to lock the attitude of the airplane, it is also helpful for landing.
4. ANGLE Mode (Former Trainer Mode)
.
.

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The ANGLE mode, also known as the ‘Trainer mode’ or ‘Attitude mode’, will limit the maximum angle of
the airplane on both roll and pitch axes. Roll and loop are not allowed in this mode, the airplane will be
stabilized all the time, independent of any stick input. This prevents the airplane from being tilted into a
larger angle that may cause a danger. As soon as the sticks are released, the airplane will be brought
back to horizontal position automatically. You can use this mode as emergency rescue, or in other
applications, e.g., to have a training for new beginners or to use for FPV. The maximum allowed angle
can be set in the Setup Menu. In addition, changing the stick rate can also affect the max tilt angle.
5. LEVEL Mode
The LEVEL mode is also known as the ‘Auto-Level mode’, ‘Auto-Balance mode’ or ‘Horizon mode’. When
operating in this mode, the airplane will be brought to horizontal position automatically when releasing
the sticks. Different from the ANGLE mode, there is no maximum angle limitation in this mode and the
airplane will be stabilized only when there is no specific control input from aileron and elevator sticks.
This mode can be used if the pilot becomes disoriented and would like to save the airplane from crashing.
6. HOVER Mode
The HOVER mode, also known as the ‘Auto-Hover mode’, provides the same functionality as the LEVEL
mode. The only difference is that when you release the sticks, the airplane will be brought to vertical
position (nose up) and keeps hovering. This mode is designed to help you to learn hovering maneuver
and reduce the probability of crashing.
GAIN ADJUSTMENT
Basic Gain
There are 3 trimming potentiometers on the front of the A3 Pro V2. They are used to adjust the basic gain
of the gyro for Aileron, Elevator and Rudder separately. Clockwise for increase, anticlockwise for
decrease. Basic gain determines the momentary reaction strength of the gyro. In general, the higher the
gain the harder the airplane will stop after rotation and the more stable and precise the airplane will fly.
But if the gain is too high the airplane will tend to oscillate at high frequency on the corresponding axis. If
too small, the operation and stability will not be so good and the airplane does not stop precisely and
overshoots. The gyro will be deactivated completely if you turn the basic gain to 0%.
For the first flight test it is recommended to start with a lower basic gain setting (e.g. 30%) and switch the
gyro to NORMAL mode. In case the airplane starts to oscillate in flight then reduce the gain of the
corresponding axis. If the control feels weak and imprecise and does not hold position when stopping
then increase the gain, according to this approach, fine tune the basic gain until you get the best
performance.
Remote Master Gain

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The [Serial RX/G] is used to control the master gain remotely. You can make a linear adjustment by using
a volume or slide lever on your transmitter or make a 3-level gain selection using a 3-position switch. This
function is optional, the master gain will always default to 100% if you do not connect it.
SETTING METHOD
There are 2 menus provided for setting up the gyro which can be accessed by the following ways:
Setup Menu:
When the gyro is working, press and hold the button for 2 seconds, release the button when LED
starts flashing White quickly.
Receiver Menu:
Turn the gyro on while holding down the button, release the button when LED lights Violet.
Setup Menu
Menu Ac cessing
To get into the Setup Menu, press and hold the
button for about 2 seconds until the LED starts
flashing White quickly. The Setup Menu contains
10 setting functions which normally only need to
be setup once after installation.
Function Selection
In the Setup Menu, the LED will flash White several times every 3 seconds in a loop and the number of
times LED flashes shows at which function item you are currently. For example, one White flashing means
the first setting “Wing Type”, after waiting about 3 seconds, a twice White flashing means the second
setting “Mount Orientation”, and so on.
Option Switching
When you reach the function that you wish to operate in, short press the button to get into it. After entering
in, the current selected option is indicated by the color of the LED. Each short press of the button
advances the option to the next value. After you finish making your selection, just wait for 5 seconds until
the LED starts blink quickly which indicates that the modified is saved and then you will be brought back
to the Setup Menu level automatically. If you do not want to change anything, just wait for timeout without
any operation.
Exit of Menu
To exit the menu keep the button pressed for 2 seconds again until the LED starts flashing White quickly.

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Setup Menu Table (* is the default setting)
Functions LED Status
Solid
Red
Solid
Green
Solid
Blue
Solid
Yellow
Solid
White
Solid
Violet
1
Wing Type White, 1 flash
Standard *
Delta-wing
V-Tail
2
Mount Orientation White, 2 flashes
Flat *
Flat
Inverted
Upright
Upright
Inverted
3
Flight Mode White, 3 flashes
1
Position-1 Blue, 1 flash
OFF *
NORMAL
LOCK
ANGLE
LEVEL
HOVER
2
Position-2 Blue, 2 flashes
OFF
NORMAL *
LOCK
ANGLE
LEVEL
HOVER
3
Position-3 Blue, 3 flashes
OFF
NORMAL
LOCK
ANGLE
LEVEL *
HOVER
4
Gyro Direction White, 4 flashes
1
Aileron Blue, 1 flash
Normal *
Reversed
2
Elevator Blue, 2 flashes
Normal *
Reversed
3
Rudder Blue, 3 flashes
Normal *
Reversed
5
Level Calibration White, 5 flashes
6
Hover Calibration White, 6 flashes
7
Maximum Angle White, 7 flashes
±30°
±60°*
±90°
8
Servo Frequency White, 8 flashes
50Hz *
65Hz
165Hz
200Hz
270Hz
333Hz
9
Gain Level White, 9 flashes
Small
Medium *
Large
10
Factory Reset White, 10 flashes
1. Wing Type
A3 Pro V2 supports standard fixed-wing, flying-wing (delta-
wing) and V-tail. After entering in this function, the color of
LED shows you the wing type currently selected. The
default setting is Standard (Red), each short press of the
button will switch to the next type. After you finish making
your selection, just wait for 5 seconds until LED starts blink
quickly which indicates that the modified is saved and then
you will be brought back to the Setup Menu level automatically. If you do not want to change anything,
just wait for timeout without any operation.
NOTES
Make sure that there are no mixing functions active on your transmitter. Have a look at the
radio’s servo monitor and verify that each stick controls only one output channel.
If two aileron servos are being used, please connect a Y-extended lead to [OUT1].
Most flying-wings have no rudder, in this case, [RUD] is unnecessary to connect.
LED Color
Description
Solid Red
Standard (default)
Solid Green
Flying-wing (Delta-wing)
Solid Blue
V-Tail

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2. Mount Orientation
A3 Pro V2 can be mounted flat or upright, and even upside
down, however, you have to ensure the arrow on the sticker
always point to the heading direction. After entering in this
function, the color of LED shows you the orientation currently
selected. The default setting is Flat, face up (Red), each short
press of the button will switch to the next type. After you finish
making your selection, just wait for 5 seconds until LED starts
blink quickly which indicates that the modified is saved and
then you will be brought back to the Setup Menu level automatically.
If you do not want to change anything, just wait for timeout without any operation.
The setting here should be the same as the mounting orientation of your unit installed in the airplane,
otherwise the gyro will not work normally.
3. Flight Mode
This function allows you preset the desired flight mode for each
position of the switch. Short press the button when LED is
flashing 3 times in the Setup Menu to get into the Position
Selection Menu. In this second-level menu, LED will flash Blue
several times every 3 seconds in a loop and the number of
times LED flashes shows at which position you are currently.
For example, one Blue flashing means “position-1”, after
waiting about 3 seconds, a twice Blue flashing means “position-
2”, and so on.
When you reach the position that you wish to set, short press the button to get into it. After entering in the
color of LED shows you the flight mode currently selected for this position. Each short press of the button
will switch to the next mode. After you finish making your selection, just wait for 5 seconds until LED starts
blink quickly which indicates that the modified is saved and then you will be brought back to the Position
Selection Menu level automatically.
LED Color
Description
Solid Red
Flat, Face up (default)
Solid Green
Flat, Face down
Solid Blue
Upright
Solid Yellow
Upright Inverted
LED Color
Description
Solid Red
GYRO OFF Mode
Solid Green
NORMAL Mode
Solid Blue
LOCK Mode
Solid Yellow
ANGLE Mode
Solid White
LEVEL Mode
Solid Violet
HOVER Mode

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To get out of the Position Selection Menu just keep the button pressed (2 seconds) again until LED starts
flashing Blue quickly, then you will be brought back to the Setup Menu.
4. Gyro Direction
Here you can reverse the gyro direction for Aileron, Elevator
and Rudder. Short press the button when LED is flashing 4
times in the Setup Menu to get into the Channel Selection
Menu. In this second-level menu, LED will flash Blue several
times every 3 seconds in a loop and the number of times LED
flashes shows at which channel you are currently. For example, one Blue flashing means “Aileron”, after
waiting about 3 seconds, a twice Blue flashing means “Elevator”, and so on.
When you reach the channel that you wish to set, short press the button to get into it. After entering in
the color of LED shows you the direction currently selected for this channel. Each short press of the
button will switch between Normal and Reversed. After you finish making your selection, just wait for 5
seconds until LED starts blink quickly which indicates that the modified is saved and then you will be
brought back to the Channel Selection Menu level automatically.
To get out of the Channel Selection Menu just keep the button pressed (2 seconds) again until LED starts
flashing Blue quickly, then you will be brought back to the Setup Menu.
VERY IMPORTANT!
It is extremely important to make sure that the gyro reacts in the correct direction for each channel
before flight. An opposite reaction of the gyro could lead to losing control or even crash!
Check the gyro direction for Aileron
Quickly move the right wing downward around the roll axis, the right aileron surface should flap down and
the left flap up as shown below.
Check the gyro direction for Elevator
Quickly move the nose of the airplane downward around the pitch axis, the elevator surface should flap
LED Color
Description
Solid Red
Normal (default)
Solid Green
Reversed

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up as shown below.
Check the gyro direction for Rudder
Quickly move the nose of the airplane to the left around the yaw axis, the rudder surface should flap right
as shown below.
5. Level Calibration
When flying in ANGLE mode or LEVEL mode, A3 Pro V2 needs to know the angle of the airplane in both
roll and pitch directions, this is achieved by calculating the attitude of its own. A small angle deviation
caused by installation can lead to an unexpected behavior when flying in ANGLE mode or LEVEL mode.
For this reason, a level calibration is recommended to offset the error caused by installation and to
establish a proper level reference of your airplane after installing the gyro.
Before calibrating, the airplane should be placed on the horizontal ground and make the wing parallel to
the ground. Make the airplane slightly nose-up because a certain elevation angle is usually required to
maintain level flight for most airplanes.
Short press the button when LED is flashing 5 times in the Setup Menu, then LED will start blink Blue
rapidly for several seconds, do not move the airplane and keep its attitude until the calibration is done.
6. Hover Calibration
As a same reason, a hover calibration is recommended to perform after installation if you want to fly with

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HOVER mode. The procedure is quite similar to that of level calibration. The only difference is in the first
step. Before calibrating, you need to lift the airplane and make it vertical to the ground instead of putting
it on the ground.
Short press the button when LED is flashing 6 times in the Setup Menu, then LED will start blink Blue
rapidly for several seconds, do not move the airplane and keep its attitude until the calibration is done.
7. MAXIMUM ANGLE
This function is used to setup the maximum allowed tilt angle
of the airplane for ANGLE mode.
After entering in this function, the color of LED shows you the
angle currently selected. The default setting is ±60deg
(Green), each short press of the button will switch to the next
value. After you finish making your selection, just wait for 5
seconds until LED starts blink quickly which indicates that the modified is saved and then you will be
brought back to the Setup Menu level automatically.
If you do not want to change anything, just wait for timeout without any operation.
8. Servo Frequency
This function is used to set the working frequency of the servos.
The analog servos can only work with 50Hz. If you do not know
what the maximum update rate that is tolerated by your servos
never use more that 50Hz. The higher the frequency the better
it is for the flight performance of the gyro but you must check
the servo specifications before increasing the setting.
Otherwise, the servos may get damaged!
After entering in this function, the color of LED shows you the
frequency currently selected. The default setting is 50Hz (Red),
each short press of the button will switch to the next value. After
you finish making your selection, just wait for 5 seconds until LED starts blink quickly which indicates that
the modified is saved and then you will be brought back to the Setup Menu level automatically.
If you do not want to change anything, just wait for timeout without any operation.
9. Gain Level
This function is used to change the level of the basic gain. After
entering in this function, the color of LED shows you the gain
level currently selected. The default setting is Medium (Green),
each short press of the button will switch between Small,
Medium and Large. After you finish making your selection, just
wait for 5 seconds until LED starts blink quickly which indicates
that the modified is saved and then you will be brought back to
LED Color
Description
Solid Red
±30°
Solid Green
±60°(default)
Solid Blue
±90°
LED Color
Description
Solid Red
50Hz (default)
Solid Green
65Hz
Solid Blue
165Hz
Solid Yellow
200Hz
Solid White
270Hz
Solid Violet
333Hz
LED Color
Description
Solid Red
Small
Solid Green
Medium (default)
Solid Blue
Large

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the Setup Menu level automatically.
If you do not want to change anything, just wait for timeout without any operation.
10. Factory Reset
This function is used to reset the gyro to factory settings. After entering in this function, the LED will
remain flashing Blue, press and hold the button for about 2 seconds until the LED starts flash Blue quickly,
release the button to confirm the reset. You will be brought back to the Setup Menu level automatically
after the restore is done.
Receiver Menu
Menu ACCESSING
To get into the Receiver Menu, press and hold
the button while turn on the power supply of the
gyro, release it when LED lights solid Violet. In
Receiver Menu you can change the receiver
type and program the channel mapping for
single line receivers.
Function Selection
In the Receiver Menu, LED will flash Violet several times every 3 seconds in a loop and the number of
times LED flashes shows at which function item you are currently. For example, one Violet flashing means
the first setting “Receiver Type”, after waiting about 3 seconds, a twice Violet flashing means the second
setting “Aileron channel”, and so on.
Option Switching
When you reach the function that you wish to operate in, short press the button to get into it. After entering
in, the current selected option is indicated by the color of the LED. Each short press of the button
advances the option to the next value. After you finish making your selection, just wait for 5 seconds until
LED starts blink quickly which indicates that the modified is saved and then you will be brought back to
the Receiver Menu level automatically. If you do not want to change anything, just wait for timeout without
any operation.
Exit of Menu
To exit the menu just keep the button pressed for 2 seconds again until the LED starts flashing Violet
quickly. After exiting the Receiver Menu, the gyro will start the initialization normally, so the new receiver
settings will take effect immediately without restarting the gyro.

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Receiver Menu Table (* is the default setting)
Functions
LED Status
Solid
Red
Solid
Green
Solid
Blue
Solid
Yellow
Solid
White
Solid
Violet
Red
Flashing
Green
Flashing
Blue
Flashing
1
Receiver Type
Violet, 1 flash
Standard*
PPM
SBUS
DSM2/X
1024
DSM2/X
2048
Spektrum
SRXL
MPX
SRXL
SUMD
IBUS
2
Aileron Channel
Violet, 2 flashes
None
CH1*
CH2
CH3
CH4
CH5
CH6
CH7
CH8
3
Elevator Channel
Violet, 3 flashes
None
CH1
CH2*
CH3
CH4
CH5
CH6
CH7
CH8
4
Rudder Channel
Violet, 4 flashes
None
CH1
CH2
CH3
CH4*
CH5
CH6
CH7
CH8
5
Mode Channel
Violet, 5 flashes
None
CH1
CH2
CH3
CH4
CH5*
CH6
CH7
CH8
6
Gain Channel
Violet, 6 flashes
None*
CH1
CH2
CH3
CH4
CH5
CH6
CH7
CH8
7
Throttle Channel
Violet, 7 flashes
None
CH1
CH2
CH3*
CH4
CH5
CH6
CH7
CH8
8
DSM Bind Option
Violet, 8 flashes
None*
DSM2
DSMX
ACCELEROMETER CALIBRATION
Before leaving the factory every unit has been carefully tested and calibrated. Usually you do not need
to perform a calibration of the accelerometer during use. However, in some specific cases, we would
suggest you re-calibrate the accelerometer to obtain better performance, these include temperature
changes those will probably cause the mechanical characteristics changes of the sensor, or replacement
of new sensor, etc. The calibration should be done on a horizontal desktop and the gyro needs to be
removed from the airplane.
Entering the Calibration Program
To access the accelerometer calibration program, press and hold the button while turn on the power of
the gyro, release it when LED starts flash Violet slowly. (FYA: Do not release the button when LED turns
solid Violet yet, or you will get into the Receiver Menu but not the accelerometer calibration program.)

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Calibration STEPS
A3 Pro V2 uses a quick approach for accelerometer calibration, there are only 2 steps corresponding to
both sides of Z axis of the unit required to be calibrated. Each step will take about 2 seconds. While
calibrating, the LED will flash Blue several seconds and then light up solid in Blue. Do not move the gyro
until the calibration is done.
Step 1 Put the gyro flat and face up on the table and make it parallel to
the desktop. short press the button, do not move the gyro while the LED is
flashing Blue quickly.
Step 2 Put the gyro flat and face down on the table and make it parallel
to the desktop, short press the button, do not move the gyro while the LED
is flashing Blue quickly.
Finish After you have finished the 2 steps above, the LED will flash Violet
once which indicates that the calibration is complete, after a successful
calibration the gyro will start the initialization automatically.
SPECIFICATIONS
Main Controller:
32-bit MCU
Sensors:
High-precision 3-axis gyroscope and 3-axis accelerometer
Gyroscope Scale Range:
±2000dps
Accelerometer Scale Range:
±4g
PWM:
920uS to 2120uS with 1520uS center length, 50Hz to 333Hz
Input Voltage:
4.8V to 8.4V
Operating Temperature:
-10℃ to 50℃
Size:
43×27×14mm
Weight:
10g (excluding wires)