KAIRUHS Manual

Hardware v2.2 · Firmware v2.144

Built in the US

Introduction
Kit Overview (Hardware v2.2)
Power & Flight Controller Integration
Installation (Displays • LoRa • Sensors)
Startup Behavior
Assignable Display Roles
Configuration (Wi‑Fi Access Point Mode)
LoRa and FastLink Radar Summary
Standalone Mode
Troubleshooting
Support & Community

1. Introduction

The Kairuhs Kit is a modular telemetry, HUD, and radar system for RC air and ground vehicles. It supports up to four simultaneous displays, each independently assigned to roles like PFD, MFD, HUD, radar, or ground dashboards.

What’s included in this manual

Hardware v2.2 controller
LoRa module and Wi-Fi radio behavior
Light and temperature sensor connections and behavior
GPS input for standalone mode
IMU port for factory-installed standalone mode
PWM input for throttle position
Firmware v2.144 features and configuration (Wi‑Fi AP UI)

Key capabilities

Four display outputs with per‑screen role and rotation
Dedicated LoRa port for peer‑to‑peer radar tracking
Light sensor for automatic brightness/dimming
Temperature sensor for ambient or component temps (motor/ESC/engine)
GPS input port for standalone operation
IMU port for factory-installed standalone units
PWM input for throttle position sensing
MSP and MAVLink protocol support
Wi‑Fi configuration for all settings; no button module menus

System Modes

Hardware v2.2 supports three operational modes:

MAVLink Mode: Connect to flight controller via UART for full telemetry
MSP Mode: Connect to flight controller via UART using MSP protocol
Standalone Mode: Use GPS, IMU, and PWM inputs without a flight controller (available on factory-configured units)

2. Kit Overview (Hardware v2.2)

Features

5V display drive for high outdoor brightness
Quad display output; assign any role to any of the 4 ports
Dedicated LoRa port for LoRa radar real-time tracking
Labeled solder pads: 5V • GND • TX • RX for FC UART hookup
Legacy button menus removed; all setup via Wi‑Fi config
Light sensor port (4‑pin) for auto‑dimming
Temperature sensor port (2‑pin) for ambient or component temps
GPS input port for standalone mode
IMU port for factory-installed standalone operation
PWM input port for throttle position
External Wi‑Fi antenna support (v2.2) for extended range

New in Hardware v2.2

GPS Port: Accepts GPS input for standalone mode operation
IMU Port: Factory-installed IMU for standalone attitude reference
PWM Port: Direct throttle position input via PWM signal
Reversed Port Orientation: Ports may be reversed compared to previous board versions

Sensors behavior

Light sensor: Detects ambient light and auto‑dims screens for dusk/night operations
Temperature sensor: Place on motor, ESC, nitro/gas engine, or use as ambient probe

⚠️ CRITICAL PORT WARNING

This warning applies only when mixing different board revisions (v2.0, v2.1, v2.2). All kits come wired and ready to plug and play.

Board v2.2 has reversed port orientation compared to previous versions. Plugging components from older boards into v2.2 with incorrect polarity can result in permanent component damage.

When mixing board revisions:

Verify the correct port for your component
Check polarity (VCC and GND positions may be swapped left-to-right)
PWM and GPS ports are not labeled on v2.2 headers — verify pinout before connecting
When in doubt, contact support for pinout verification specific to your board revision

Common risks when mixing revisions:

GPS plugged in with reversed polarity will burn out immediately
LoRa module in a display port risks damage
Sensors in wrong ports will not function

If your kit came together in one package, everything is already properly wired and will plug and play.

Caution

Do not mix ports. LoRa must plug into the LoRa port only. Do not insert the LoRa module into a display port. Do not connect FC wiring into sensor ports, or sensors into display/radio ports.

3. Power & Flight Controller Integration

Power sources

The board can be powered through multiple methods. Important: Only use ONE power source at a time.

Power input options (in order of preference):

FC-IN port (main power input – UART connector with 5V pin)
Solder pads on the rear of the board (5V and GND)
PWM port (can be used for standalone mode power)
USB Port on the main board

⚠️ Power Safety:

Never power through multiple inputs simultaneously
Example: If powering through PWM port, do NOT also connect power via solder pads or FC-IN port
If powering via a source other than PWM port, remove the 5V pin from the PWM connector to prevent conflicts

UART wiring (MAVLink or MSP)

Pin assignments:

Green → FC RX (connects to FC TX)
Yellow → FC TX (connects to FC RX)
Red → +5V
Black → GND

Protocol settings:

MAVLink: Baud rate 115200
MSP: Baud rate 115200
Make sure ground (GND) is connected along with RX and TX

SpeedyBee F405 Wing / F405 Wing Mini

Plugs directly via the 6‑pin JST UART (TX/RX/5V/GND). No adapters required.

Configuration tip: Confirm the correct UART and set the appropriate protocol (MAVLink 115200 or MSP 115200) under Ports in your flight controller configurator.

INAV Compatibility Note:

INAV 7.x is the most stable with MAVLink
MSP works with INAV 7.x and newer

Tested Flight Controllers:

SpeedyBee F405 Wing / Mini Wing
ATOMRC NAVI F405
Skystars F405HD

4. Installation (Displays • LoRa • Sensors)

Displays

Insert 8‑pin cables fully until seated; do not force
Match orientation: Red = 5V, Black = GND
Available display types: 1.14″ (ST7789) and 1.44″ (ST7735)
Display type is configured in the Advanced tab

LoRa Module

Plug into the LoRa port only
Never plug into a screen port — this may damage the module

Sensors

Temp sensor: uses a 2‑pin connector
Light sensor: uses a 4‑pin connector
Headers may not be labeled; verify pinout before powering on
Contact support if uncertain about pin assignments

GPS Input (Standalone Mode)

Connect GPS module to the GPS port
Verify polarity before connecting — reversed connection will damage GPS
Used in standalone mode for position, speed, and heading data

IMU Port (Standalone Mode)

Factory-installed IMU for standalone attitude reference
Provides roll, pitch, and yaw data without flight controller
Only available on standalone-configured units

PWM Input (Throttle Position)

Connect a Y-splitter from your throttle servo cable
Provides direct throttle position to the system
Can power the board through this port
If powered differently, remove the 5V pin from the PWM connector

5. Startup Behavior

Boot splash shows firmware version (v2.144), followed by system checks.

Status indicators:

Green = OK, component functioning
Red = No data or fault detected

System checks (displayed on screen):

MAVLink/MSP (Flight Controller connection)
Radio (LoRa module)

6. Assignable Display Roles

Each display (1–4) can be assigned independently in the config. You can duplicate roles across screens and rotate each display individually.

6.1 Primary Flight Display (PFD)

Speed tape with 3‑second trend vector
Roll and pitch horizon
Altitude tape
Compass and heading (compact or full layout)
Return‑to‑home arrow and distance to home
Variometer
Satellite count; icon turns green at 7 or more satellites
Selectable units for speed and altitude

6.2 Multifunction Display (MFD)

Throttle position
Flight mode display (MAN • ACR • HOR)
Voltage or fuel‑style gauge
Current (A) and power (W)
Battery remaining
Battery voltage, per‑cell voltage, cell count
Flap and gear indicators
Attitude indicators: roll, pitch, yaw
RC channel mapping: throttle, flight mode, gear, flaps can be assigned to any channel 1–8 and inverted if needed

6.3 HUD Display

Speed, altitude, pitch, roll, heading
Distance to home
Satellite count turns red when no satellites are active
HUD vertical offset adjustable
Optional invert for reflective HUD glass alignment

6.4 Air Radar Display

Live tracking of real and simulated targets
Circular radar layout with adjustable range and compass ring
Labels: ID (vehicle or pilot), altitude, distance
Hostiles show up red
Top legend: two radio link blocks (LoRa & Wi-Fi) indicate status — green = active, red = inactive; node count shown directly beneath blocks
Bottom legend: vehicle ID, pilot ID
Range scaling via transmitter; assign any channel 1–8 and set min/max endpoints in feet

Note: More satellites yield better positional accuracy and visibility on others’ radars.

6.5 Track Dash 1 (Ground)

Throttle bar segment
Speed
Temperature
Tachometer derived from throttle
Voltage and arm time
Shift-light bar LEDs (green → yellow → red) with flashing limiter at the top

Corner LEDs:

Top-left: Temperature (green, yellow, red, flashing red at critical)
Bottom-left: Battery (green, red, flashing red at critical)
Top-right: GPS satellite count (red <7, yellow 7–17, green 19+)
Bottom-right: MAVLink/MSP activity (green if active, dim if stale)

6.6 Gauges (Ground)

Voltage gauge
Temperature gauge
Fuel level gauge (derived from voltage)

Temperature LED (top-center):

Dim red = idle
Solid red ≥ 75 °C
Flashing red ≥ 85 °C (critical)

6.7 Street Dash (Ground)

Center: RPM gauge (derived from throttle)
Right: Speed gauge
Left: Fuel gauge (derived from voltage), Temperature gauge
Selectable speed units (MPH / KMH / Knots)
Theme color applied to all gauge elements

6.8 Radio (Ground)

Touchscreen-style radio with on-timer roll

6.9 Track Dash 2 (Ground)

Voltage display
Fuel level (derived from voltage)
Temperature display with LED indicator
Satellite count
Left bar-segment gauge: RPM (derived from throttle)
Right bar-segment gauge: Speed (up to 55 mph)
Selectable speed units (MPH / KMH / Knots)
Theme color applied to gauge elements

6.10 License Plate (Ground)

Plate styles with custom plate text (up to 10 characters)

6.11 Inclinometer (Ground)

Two large gauges:

Left: Compass
Right: Attitude (roll and pitch, limited to ±40°)
Voltage displayed at top
Speed displayed at bottom
Theme color applied

6.12 Radar (Ground)

Landscape square-grid layout with theme-colored grid
Larger fonts in key areas for readability
Labels: ID, altitude, distance (same as Air Radar)
Hostiles show up red
Same functionality as the circular Air Radar, adapted for ground use

6.13 Double DIN GPS (Ground)

Modern car-style GPS navigation display

Metrics:

Top right: On time
Right side (below on time): Speed
Right side (below speed): Temperature
Bottom: Satellite count and heading

7. Configuration (Wi‑Fi Access Point Mode)

7.1 Enter AP Mode

Power on or reset the device and immediately hold BOOT button
AP instructions will appear on screen
Connect to the WiFi network shown (default: KAIRUHS_Config, password: kairuhs123)
Open a browser and go to http://192.168.4.1

7.2 Tabs and Settings

Available tabs: Basics, Gauges, Radio, Ground, Advanced, Manual

BASICS Tab

Warnings

Enable/disable individual warnings and set thresholds:

Stall
Overspeed
Overcurrent
Low Altitude
Altitude Ceiling
Low Voltage

Behavior: Bold red box centered on screen with uppercase label (e.g., VOLTAGE, STALL, ALTITUDE)

Per-screen behavior: Choose which displays show the overlay

Supported on: PFD, MFD, HUD (Air), Radar (Air)
Not supported on: Gauges Pages (Air), or any Ground roles

Flash options:

Select which displays flash during warnings
Option to flash Air Radar or Air HUD red with warnings, or independently

Units

Speed: mph, kph, or knots
Altitude and distance: feet, meters, or yards

Display customization

Brightness: 1–10
PFD compass layout: compact or full
MFD fuel gauge mode: voltage or fuel bar

Identity and labels

Vehicle ID: 4 characters
Pilot ID: 4 characters
Team selection: 1 or 2

Radar label and display toggles

Radar range
Show ID label
Label source: pilot or vehicle
Show altitude
Show distance
Visibility filter: Friends / Foes / All / None
Eject factor: 1.0 ejects at edge, 1.2 ejects slightly past

GAUGES Tab

Choose across air gauges on multiple screen pages. Tune positions, face size, and page locations.

Available gauge types:

Airspeed (IAS): Forward speed using 3D ground speed. Units follow Speed Units setting (MPH/KMH/Knots).
Altimeter: Altitude display. Units follow Alt/Dist Units setting (Feet/Meters/Yards).
VSI (Vertical Speed): Climb/sink rate. Units follow altitude units setting.
Turn Coordinator: Bank/roll indicator with realistic slip ball physics.
Heading: Compass heading indicator.
RPM: Derived from throttle position with smoothing for realistic behavior.
Manifold Pressure: Simulated from throttle position and current draw.
Oil Pressure: Simulated from throttle and amp draw with realistic dynamics.
Oil Temperature: Simulated from throttle, current draw, and airflow (3D ground speed). Scale: 0–300°F with green/yellow/red bands.
Fuel Quantity: Based on per-cell voltage (total V ÷ cell count). Maps ~3.30–4.20V to 0–100% with left/right mirror needles.
Coolant Temperature: Simulated from throttle, current draw, and airflow (3D ground speed). Scale: -50–150°C.
Attitude (AHI): Classic blue/brown artificial horizon with roll and pitch. Includes dim mode for lower brightness to match ambient lighting.
Mono AHI (Page 4): High-contrast monochrome artificial horizon for clean, low-glare layouts.
Gear Indicator (Page 4): Shows gear state with color logic (Green = Up, Red = Down). Gear channel assignment configured in Advanced tab.
Flaps Gauge (Page 4): Flap angle indicator with color logic (Green = 0°, Yellow = 20°, Red = 40°). Flaps channel assignment configured in Advanced tab.
Battery Voltage Gauge (Page 4): Segmented red/yellow/green arcs that flash when voltage crosses warning threshold (set in Basics tab).

Gauge Positioning:

X coordinate: Left to right (increasing X moves right)
Y coordinate: Up to down (increasing Y moves down)
Page: Set to 1, 2, 3, or 4 (only gauges matching active page render)
Face size: Diameter in pixels (typical range 30–120px)

Theme Color: All gauges follow your selected global Color Theme for needles, arcs, bands, and markings. Changing the theme updates every gauge instantly.

Artificial Horizon Dim Mode: The Attitude (AHI) gauge can be bright in low-light conditions. Enable Dim Mode to tone down the colors for better ambient matching.

RADIO Tab

The platform supports two radios: Wi-Fi (high-speed/mid-range) and LoRa (mid-speed/long-range). These may be used independently.

⚠️ Note: Hybrid mode is currently in development and not available in this firmware.

Master Radio Status

0 — Off: All radio systems disabled
1 — Wi-Fi: Wi-Fi telemetry only
2 — LoRa: LoRa telemetry only

Wi-Fi Settings

Channel: US: 1–11. Choose a quiet channel if interference appears.
TX Power: Adjustable output. High TX power may increase noise or cause SPI instability.
Long-Range (LR): Optional extended-range mode. Verify local regulations.

⚠️ Power Warning: High TX power can potentially cause SPI communication issues, especially when using multiple ST7789 panels. If experiencing screen corruption or instability, try reducing TX power.

LoRa Settings

Region: US (902–928 MHz), EU (863–870 MHz), or Custom
Center Frequency:
- US: 915.0 MHz
- EU: 869.5 MHz (common)
Bandwidth:
- EU: 125/250 kHz
- US: may use 500 kHz
TX Power: Adjustable. Antenna required before transmitting.

⚠️ Antenna Warning: Never transmit without a properly matched antenna.

Quick Band Hints

US (FCC): 902–928 MHz ISM. 500 kHz permitted.

EU (RED): 863–870 MHz:

868.0–868.6
868.7–869.2
869.4–869.65

Tip: 869.5 MHz is a common EU selection.

On-Screen Indicators

Two blocks show link status:

Green = active
Red = inactive

Node count appears below these indicators.

Compliance

Users are responsible for ensuring regulatory compliance in their region. Follow local laws regarding frequency, power, and duty cycle.

Troubleshooting

No targets shown: Verify radio mode, antenna connection, region/BW match, and visibility filters
Unstable behavior: Lower TX power, confirm antenna load, verify power supply stability
All devices must share identical LoRa parameters: region, frequency, bandwidth, spreading factor

GROUND Tab

Speed Units

MPH / KMH / Knots — applies to all ground screens showing speed

Dash Theme

Primary Theme Color: Sets accent color for gauges, bars, and legends
Text Color: Sets text color for ground dashboards
Ground Radar Theme Color: Sets grid and accent colors for Ground Radar

Roles

Assign what each screen shows while in Ground mode:

AIR pages: PFD, MFD, HUD, Air Radar, Gauges Page 1–3
GROUND pages: Street Dash, Track Dash 1, Track Dash 2, Ground Gauges, Radio, License Plate, Inclinometer, Radar (Ground), Double DIN GPS

Display/rotation constraints:

1.44″ screens can show AIR pages in any orientation
1.14″ screens can show AIR pages in portrait only
GROUND pages require landscape orientation

RC Mapping

RC Throttle Chan / Invert: Maps RC channel for throttle-derived features (RPM bars) with inversion option
Throttle Bottom (%): Trims low end so brake doesn’t register as throttle

License Plate (Ground)

Plate Text: Custom text up to 10 characters
Plate Type: Choose style (CA Classic Blue, Digital CA, Canada, etc.)

ADVANCED Tab

System Mode

MAVLink: Connect to FC via UART for full telemetry (baud 115200)
MSP: Connect to FC via UART using MSP protocol
Standalone: Use GPS, IMU, and PWM without flight controller (factory-configured units only)

Display Speed and Screen Management

Disabling unused screens can increase CPU speed, reduce CPU load, and increase frame rate. Using only 1-2 screen ports can speed up the system by 2x-3x.

Display Refresh Rate:

16 MHz: Most stable, slowest refresh
20 MHz: Balance between speed and stability
27 MHz: Default setting
40 MHz: Advanced users, may cause issues on some setups
80 MHz: Maximum speed, use with caution

Stability Guidelines:

Lower speeds = more stable
Higher speeds = faster refresh but potential for screen tearing, corruption, black screens, or freezes
ST7789 (1.14″) displays are more sensitive to high speeds
ST7735 (1.44″) displays are more stable

Displays & Rotation

Display Type:

0 = ST7735 (1.44″, 128×128)
1 = ST7789 (1.14″, 135×240)

Screen Rotation: 8 modes: 0°, 90°, 180°, 270° and their mirrored variants

Display/rotation constraints:

1.44″ screens: AIR pages in any orientation
1.14″ screens: AIR pages in portrait only, GROUND pages require landscape

Roles

Assign what each screen renders in AIR or GROUND contexts. Roles saved per slot (Screen 1–4):

AIR roles:

PFD, MFD, Radar (Air), HUD, Gauges Page 1, Gauges Page 2, Gauges Page 3

GROUND roles:

Track Dash 1, Track Dash 2, Street Dash, Ground Gauges, Radio, License Plate, Inclinometer, Radar (Ground), Double DIN GPS

HUD Vertical Offset

Shifts the HUD up/down. Range: 0–112

RC Mapping (Chan/Invert)

Displays current RC channel mapping and inversion flags for:

Flaps
Gears
Flight Mode
Throttle

Use these to verify inputs used by dashes/gauges.

TX Adjustable Radar Range

Enable (0/1): Turn channel-based range control on/off
Channel (1–8): RC source used to scale range
Invert (0/1): Flips channel sense
Bottom/Top (ft): Min/max feet for mapping (values align to 25 ft steps)

When enabled, visible radar radius maps to selected RC channel between Bottom–Top.

TX Screen / Role Switching

Control how screens switch and cycle roles using transmitter.

Inputs:

Screen Select Channel: Chooses active screen
Role Cycle Channel: Cycles through enabled roles on selected screen
Default Screen: Used when no Screen Select channel assigned

Per-Screen Role Enable/Disable: Each screen includes checkboxes to disable roles you don’t want screens to switch into during operation. Only enabled roles included when cycling mid-flight or mid-drive.

Simulation

Sim Enabled (0/1): Master toggle
Spawn Chance %: Probability per tick for new sim target
Max Sims on Radar: Cap on concurrent simulated targets
Pursuers Enabled (0/1): Allow chase logic
Pursuer Chance %: Probability new sim is pursuer
Show Sims Mode: All / Friendly / Hostile / None
Friendly Pursuer %: Likelihood pursuer is friendly
Pursuit Aggressiveness (1–10): Higher = tighter turns/closing behavior
Follow Distance (ft): Nominal spacing for followers
Min/Max Chase Speed (ft/s): Speed band for pursuit logic
Vertical Gain (ft/s per ft): Climb/sink response to altitude error

Save Behavior

Use Save Settings at the bottom of the page to write changes. The device reboots into normal mode with the new configuration.

8. LoRa and Wi-Fi Radar Summary

Real-time peer-to-peer radar tracking for nearby targets in air and on ground. Supports up to about 15 pilots. Higher network congestion reduces update rate.

Indicative range (HW v2.2 with external antennas):

Ground → air: ~1500 ft @ 20 Hz (typical)
Air → air: often farther

Display features:

Circular air radar and landscape square-grid ground radar
Target labels: ID, altitude, distance
Hostiles show up red
Top legend: radio status (green = active, red = inactive), satellite count, current radar range
Bottom legend: vehicle ID, pilot ID, radio node presence

Note: More satellites yield better positional accuracy and visibility on others’ radars.

9. Standalone Mode

Standalone mode is only available on factory-configured units with pre-installed IMU.

Requirements for Standalone Operation

With only the board, you get basic orientation data. For full functionality:

Required connections:

GPS module → GPS port (provides speed, heading, position)
PWM throttle cable → PWM port (provides throttle position)
Power → FC-IN, solder pads, or PWM port (choose ONE source only)

Setup and Safety

⚠️ Critical:

PWM and GPS ports are not labeled on v2.2 headers
Verify pinout before plugging in and powering
Board can be powered through PWM port
Never power through multiple ports simultaneously (e.g., solder pads AND PWM port)

10. Troubleshooting

No MAVLink/MSP Data

Verify TX and RX are not reversed
Check baud rate: 115200 for both MAVLink and MSP
Confirm correct UART in flight controller configurator
Ensure ground (GND) connection along with RX and TX
Try INAV 7.x if using INAV with MAVLink

No Radar Targets

Ensure radio module is connected and enabled in Radio tab
Verify radio settings match other pilots/drivers (channel, bandwidth, frequency)
Check visibility filters (Friends/Foes/All/None)
Confirm antenna is properly connected

Blank Display

Confirm correct display driver (ST7735 or ST7789) in Advanced tab

Display Issues: Screen Tearing, Corruption, Black Screens, Color Shifting

These issues particularly affect ST7789 (1.14″) displays and can be caused by:

Common causes:

High SPI speed
Radio transmitting
Insufficient power supply

Systematic Troubleshooting:

Start with minimal configuration:
- Disconnect all modular components: LoRa, temp sensor, light sensor
- Test with one screen only
- Test each display individually
- Test each port individually
- Swap cables and displays to identify weak components
Add components incrementally:
- Once one screen works, add another
- Continue adding until corruption appears
- Identify the threshold where problems begin
Firmware tuning:
- Lower SPI speed (most effective solution)
- Start at 16 MHz for maximum stability
- Gradually increase if needed
- 27 MHz is the default setting
- Disable unused screens to reduce CPU load
Hardware solutions:
- Extend TFT cables (may help reduce EMI)
- Keep cables away from antennas and 2.4 GHz receivers (ELRS, Spektrum)
- Add capacitor to power input pads (may help stabilize power)
- Try different flight controller if available
Radio considerations:
- Reduce TX power
- High TX power draws more current and can cause SPI issues
- Radio off = more stable displays
Power considerations:
- USB power with multiple displays almost always causes issues
- Use external 5V supply for best results
- Adequate power supply is critical with multiple screens
Display considerations:
- ST7735 (1.44″) displays are more stable and rarely show issues
- ST7789 (1.14″) displays are more sensitive to EMI and power issues
- Consider using ST7735 displays if experiencing persistent problems

If problems persist:

Contact support
Troubleshoot thoroughly first before requesting replacements
Provide detailed information about testing performed

Tested configurations:

Speedybee F405 Wing/Mini Wing: All 4 screens work with radio inactive
ATOMRC NAVI F405: Verified working
Skystars F405HD: Verified working
Extending screen wires helps reduce interference
Proper cable routing away from antennas is essential

11. Support & Community

Email: kairuhsconsole@gmail.com

Thingiverse: https://www.thingiverse.com/kairuhshq/designs

Facebook: https://www.facebook.com/groups/1231576258453632/

YouTube: https://www.youtube.com/@Kairuhshq

Instagram: https://www.instagram.com/kairuhshq/

Recommendations & Requests

Suggestions for new screen types or specific PFD/MFD layouts are always welcome. Share your ideas via email or social media — we consider all submissions for future updates.

We improve the platform through community feedback. Send build photos, flight footage, and notes; we may feature your work.

Thanks for flying KAIRUHS. Fly low. Fly fast. Fly smart.

Manual version: Hardware v2.2 · Firmware v2.144
Last updated: February 2026