Common Features (Both Units)

The Aircraft Hardware Unit and GCS Hardware Unit are identical hardware. The distinction between roles is determined by the firmware loaded on the device. Firmware files ending in _default configure the unit for aircraft use; files ending in _gcs configure it for GCS use. Units can be converted between roles by flashing the appropriate firmware (see Firmware updates).

Callout Key

1. LOS1 / LOS2 antenna ports (915 MHz, SMA female, standard polarity)
2. SAT antenna port (Iridium / Inmarsat, SMA female)
3. I/O connector (12-pin Molex Nano-fit; power, UART, digital I/O, 5 V accessory)
4. USB-C port (computer interface; cannot supply unit power)
5. STATUS and LINK LED indicators
6. RESET button (also engages USB DFU mode)
7. Mounting flange and through-holes

Connectors

Port Label	Description
LOS1	868-928 MHz antenna, SMA
LOS2	868-928 MHz antenna, SMA
SAT	Iridium or Inmarsat satellite antenna, SMA
USB-C	Computer interface / firmware / configuration
Flight Controller Port	Aircraft telemetry interface (Aircraft Hardware Unit)
Power	2S/3S battery or regulated supply input

Caution

Pay careful attention to the gender and polarity of SMA connectors, cables, and adapters during installation. The LOS1, LOS2, and SAT ports on the Horizon Hardware Unit are standard-polarity SMA female jacks. Included antennas use RP-SMA connectors; use the provided adapters. Incorrect mating will prevent antenna connection and may damage connectors.

Caution

Maximum SMA mating torque is 5 in-lbs (0.57 N-m). Applying excessive torque may damage the connector. If additional vibration resistance is required, apply a bead of staking compound to the exterior of the connector after mating. Do not apply thread-locking or staking compound directly to the connector threads.

Horizon has two independent LED indicators. STATUS provides insight to overall device operation and LINK to LOS link connection.

STATUS LED

Pattern	Meaning
🟢 Solid Green	Power good (normal)
🔴 Blinking Red	Bootloader mode (abnormal during operation)
🟡 Flashing Amber	Firmware update in progress — do not unplug the device

LINK LED

Pattern	Meaning
🟢 Blinking Green	LOS link connected
🔴 Blinking Red	LOS link lost

I/O Connector (Flight Controller / Power Interface)

The I/O connector is a 12-pin, right-angle Molex Nano-fit header. It is the primary interface for power input, flight controller UART communication, hardware flow control, digital I/O, and 5V accessory power output.

Pin	Name	Type	Description
1	VSUPP	Power	Main power input (6–13V DC)
2	UART_RTS	Output	UART hardware flow control — RTS output from radio
3	UART_CTS	Input	UART hardware flow control — CTS input into radio
4	UART_TX	Output	UART TX data line
5	UART_RX	Input	UART RX data line
6	5V_ACC	Power	Switched 5V output (for low-power accessories; max 250 mA recommended)
7	GND	Power	Power/signal ground — recommended: VSUPP return lead
8	GND	Power	Power/signal ground — recommended: UART/IO ground
9	GND	Power	Power/signal ground — recommended: 5V_ACC return
10	NC	—	Electrically unconnected. Do not connect.
11	DIGITAL_IN	Input	Dedicated digital input pin. User-configurable functionality. Defaults to SBUS input when the device is configured for GCS operation.
12	DIGITAL_OUT	Output	Dedicated digital output pin. User-configurable functionality.

Caution

The USB-C connector cannot be used to power the Horizon Hardware Unit. Full power must be supplied via the VSUPP and GND pins of the I/O connector.

Connector Part Numbers

Item	Molex Part Number
I/O connector on Horizon Hardware Unit	1053141212
Recommended mating connector housing	1053081212
Recommended crimp terminals (select by wire gauge)	1053002100 or 1053001100

Caution

Use only official Molex crimp tooling when assembling wiring harnesses. Unofficial tooling may produce a substandard crimp, compromising reliability.

Reset Button

A small hole in the enclosure provides access to the device reset button. This button can also be used to engage USB Device Firmware Update (DFU) mode for firmware recovery.