FeiYu Tech FY-21AP User Manual

Page 2

GuiLin FeiYu Electronic Technology Co., Ltd http://www.feiyudz.cn E-mail:

Initialization / Reset Process

Install the jumper as shown in this picture:
Power-ON the FY-21AP and keep it stationary for at least 20 seconds. You will notice the red light
blink with two different rates.
After 20 seconds the re-setting / initialization is complete. Disconnect the power, unplug the
jumper & remove it (keep safe for future use).
NOTE: Carry out this re-setting procedure only if the above occur. We do not recommend

regular re-setting. It is not necessary and not recommended.

The stabilizer unit does not need to be in a horizontal position during initialization. However, you
must ensure there is no vibration during this process. If you suspect shaking occurred, just restart
the initialization / resetting process.

FLIGHT INDICATOR (Red and Blue Light)
Red LED

The red LED indicator will light up when the FY-21AP is ON. The flight mode of your autopilot is
indicated by how this LED flashes or stays solid.

By observing this red LED, you can easily re-confirm your Flight Mode switch settings of your
radio:

Flight
mode

MODE 1:
Stabilization
not active

MODE 2:
Stabilization
active

Autopilot Mode
3: (circling mode)

Autopilot
Mode 2:
RTL

MODE 3:
Fixed-
Altitude
Flight

Red LED
light
indicator

Continuous
uniform
flashing

Stay ON
solid

Continuous, single
flash each loop

Continuous,
double flash
each loop

Continuous
flashing.
3 times each
loop

Blue LED

The Blue LED light indicates the GPS status & vibration level experienced by the FY-21AP:

Status

Too much vibration

(flight stabilization

will not function)

No GPS

GPS data

received

GPS location fixed

(> 5 satelites)

Blue LED
light
Indicator

Stay ON solid

Stay OFF

solid

Continuous

Single flash each

loop

Continuous double flash

each loop

The interface and features of the GPS circuit board

TX0：Data transmission. Connect to the FY-21AP RX pin.
RX0：Data receive. Connect to FY-21AP TX pin.
Interface Features: TTL level
Baud rate: 38400
Data bits: 8
Stop bits: 1
Parity: None
GPS Data refresh rate: 10Hz

If GPS cannot fix the aircraft location
(minimum 5 satellites), only Mode 1 (Deactivated) and Mode 2 (Stabilized Mode) will
function. Mode 3 and Autopilot will not be functional.

Install the GPS Module with the antenna face up (see above). DO NOT install next to metal or
carbon fiber and other shielding material, which may block satellite signal.

Install the GPS Module away from electromagnetic sources such as ESC‟s, power wires,
servo wires and video transmitters.

GPS – Satellite Signal Lost During Autonomous Flight



GPS provides the aircraft geographic positioning, altitude, speed and flight direction.



With this data the FY-21AP can perform the Autopilot Modes.



In case GPS signal is lost during flight – e.g. in very cloudy weather - the autopilot will be
switched off automatically. The FY-21AP will go into Mode 3: Fixed Altitude Stabilized
Flight Mode until GPS position is regained.



After GPS signal is regained the plane will resume the Autopilot Mode.

FY-21AP Version II - Schematic diagram of balance control:

Schematic diagram of navigation control:

The Interface of FY-21AP

Panel for Pin Interface:

①Channel 8is optional. It will output throttle control signal only if the FY-21AP is linked to the FY-606
Data Radio

FY-21AP Electrical Connection and Diagram
Power supply



The FY-21AP operates between 4 to 6 volts input.



FY-21A is powered via the Receiver connection.



If your plane is Electric powered, the Receiver power supply is normally from the ESC built-in
Battery Elimination Circuit (BEC).



Alternately, you can supply the Receiver and FY-21AP via a separate BEC.



For Gas or Nitro powered planes, you will require a battery to power the Receiver and FY-21AP.

Connection to RC Receiver

a) Connection between the FY-21AP and Receiver output is via the supplied wire:

FY-21AP requires a minimum of 6-channel RC receiver.
b) 3 Receiver channels are used for aileron, elevator and rudder signal output. Connect these 3 receiver

output signals to the FY-21AP with the supplied wires.

2 free Receiver channels are required to control the FY-21AP Flight Modes (3-position switch) and
Autopilot Mode (3-position switch).

d) Example of 6 channel receiver utilization (refer page 16 ):

Channel 1 = Aileron Signal Output
Channel 2 = Elevator Signal Output
Channel 3 = Throttle Signal Output
Channel 4 = Rudder Signal Output,
Channel 5 = Switch IN1 controlled by radio 3-position switch for FY-21AP Flight Modes.
Channel 6 = Switch IN2 controlled by radio 3-position switch for FY21AP Autopilot Modes.

SWITCH DEFAULT MODES
Switch IN1

If the FY-21AP does not detect any incoming signal to the Switch IN1 Channel Input, it will
automatically engage Mode2: Stabilized Mode.

b) However, we DO NOT recommend flying the unit with no signal input to the FY21AP Switch

Channel. It is possible that the auto balance will not function properly if the Switch channel is left
open.

If you do not have a 3 position switch available on your radio, you can set the flight Modes using a
two position switch. However you need to omit one of the flight modes.
For example, you may choose to set Mode 1 (Stabilization Deactivated) and Mode 3: (Fixed
Altitude Flight Mode) on your two-position switch, therefore omiting Mode 2 (stabilized flight).

Red LED

Blue LED