Dynon SkyView / SkyView HDX

The Dynon SkyView is the most common EFIS used with OnSpeed. It provides comprehensive flight data including IAS, pitch, roll, G-loads, OAT, altitude, fuel, and even its own Percent Lift (AOA) reading.

What Dynon Provides

When connected, OnSpeed receives from the SkyView:

Data	Field	Units
Indicated Airspeed	efisIAS	knots
Pitch Angle	efisPitch	degrees
Roll Angle	efisRoll	degrees
Lateral G	efisLateralG	G
Vertical G	efisVerticalG	G
Percent Lift	efisPercentLift	0–99%
Pressure Altitude	efisPalt	feet
Vertical Speed	efisVSI	fpm
True Airspeed	efisTAS	knots
Outside Air Temp	efisOAT	°C
Fuel Remaining	efisFuelRemaining	gallons
Fuel Flow	efisFuelFlow	gph
Manifold Pressure	efisMAP	inHg
Engine RPM	efisRPM	rpm
Percent Power	efisPercentPower	%
Magnetic Heading	efisMagHeading	degrees

All of this data is logged to the SD card for post-flight analysis.

Dynon Serial Protocol

The SkyView outputs two message types:

• !1 message — ADAHRS data (74 bytes): attitude, airspeed, altitude, G-loads, heading, time
• !3 message — EMS data (225 bytes): engine parameters, fuel, OAT, percent lift

Both messages must be enabled for full functionality.

Dynon Configuration

Step 1: Identify the Serial Port

The SkyView has multiple serial ports on the rear connector. Choose one that isn't already assigned to autopilot, transponder, or other devices.

Step 2: Configure Serial Output

On the SkyView:

1. Go to SETUP menu
2. Navigate to SERIAL PORT SETUP
3. Select the serial port you'll use for OnSpeed
4. Set the following:
   • Protocol: ADAHRS + EMS output
   • Baud Rate: 115200
   • Output: Enabled

Baud rate must be 115200

The Dynon defaults to 9600 baud. OnSpeed requires 115200 baud. If you leave the default, OnSpeed will receive garbled data. This is the #1 most common configuration mistake.

Step 3: Wire the Connection

Connect the Dynon serial TX pin to the OnSpeed RX pin (GPIO 11):

• Find the TX pin for your chosen serial port on the SkyView rear connector
• Run a wire from Dynon TX to OnSpeed RX
• Connect grounds between the two devices
• The Dynon uses RS-232 levels; the OnSpeed board has an ADM3202 RS-232 level shifter

Step 4: Configure OnSpeed

1. Connect to OnSpeed WiFi (OnSpeed / angleofattack)
2. Open the configuration page at 192.168.0.1
3. Set EFIS Type to ADVANCED (this is the SkyView/HDX setting)
4. Save and reboot

Step 5: Verify

1. Power on both the Dynon and OnSpeed
2. Use the SENSORS console command — you should see EFIS data fields populated
3. Check efisAge — should be a small number (< 500 ms), meaning data is arriving regularly

Common Mistakes

Problem	Cause	Fix
No EFIS data at all	Wrong baud rate	Set Dynon to 115200 baud
No EFIS data at all	TX/RX swapped	Swap the serial wire connection
No EFIS data at all	Wrong serial port	Verify which Dynon serial port you wired to
Partial data (IAS but no OAT)	EMS output not enabled	Enable both ADAHRS + EMS output on the Dynon
Wrong EFIS type	EFIS Type not set to ADVANCED	Change EFIS Type in OnSpeed config
Garbled data	Baud mismatch	Both must be 115200

Dynon Percent Lift

The Dynon SkyView has its own built-in AOA system that outputs a Percent Lift value (0–99%). OnSpeed logs this as efisPercentLift. The Dynon uses a linear model: AOA% = gain × pressure_ratio + offset, configured per flap setting.

This is useful for cross-calibration — you can compare OnSpeed's AOA computation against the Dynon's to validate both systems.

Dynon V-speeds are in meters/second

If you ever look at V-speed values in the Dynon configuration file, they're stored in meters per second (multiply by 1.94384 to convert to knots). This doesn't affect the OnSpeed serial interface — IAS comes across in knots.

Dynon SkyView Configuration File

The Dynon stores its configuration in a .dfg file that can be saved to and loaded from USB. This file contains serial port settings, V-speeds, AOA model parameters, and all other system configuration. If you need to verify your serial port settings, you can inspect this file on a computer.