Build the drone, stage by stage

Safety, tools and LiPo handling

A 450 mm drone with 10-inch propellers and a 60C LiPo can cause serious injury and fire. Set these habits before you touch a part.

You need

Safety glasses, fire-safe LiPo bag, balance charger, LiPo voltage alarm, multimeter, soldering station, thread lock, ST-Link programmer, oscilloscope if you can borrow one

Steps

1. Read the whole tutorial once before buying anything.
2. Agree one rule for the team: propellers stay off unless the drone is on a rig or in an open flying area.
3. Charge only with a balance charger, attended, in a fire-safe bag. Never charge or fly a swollen or damaged pack.
4. Keep a separate power switch or a clear way to unplug the battery fast.
5. Check your national drone rules before any outdoor test.

Check before moving on

• Everyone on the team knows the propeller rule
• LiPo charging setup is ready and fire-safe
• Tools are on hand, including a multimeter and ST-Link

Parts list and sourcing

Parts must suit each other. The motor, propeller, ESC and battery are one system. Our list came from talking to experienced builders.

You need

See the full parts list and costs

Steps

1. Buy the airframe and propulsion set: F450 frame, 4 × EMAX XA2212 980 KV motors, 4 × Hobbywing Skywalker 30A ESCs, 1045 propellers (2 CW, 2 CCW, plus spares), and a 3S 5200 mAh 60C LiPo.
2. Buy the avionics: STM32H743VIT6 board, MPU6500, BMP280, QMC5883L, NEO-M8N GPS, ESP32-WROOM-32, nRF24L01+PA+LNA.
3. Buy the transmitter set: ESP32 Devkit V1, 2 joysticks, ADS1115, 0.96-inch SSD1306 OLED, a second nRF24L01+PA+LNA, an 18650 cell and its charging and regulator parts.
4. Buy power parts: MP1584 buck converter, a power distribution board, ceramic and electrolytic capacitors, and silicone wire.
5. Test what you can on arrival. Read each sensor's ID register, because identical-looking boards can contain different chips.

Check before moving on

• Propulsion parts are all branded and matching, with no mixed batches
• Spare propellers are on hand
• Sensor boards have been checked for clones
• You have budgeted for breakage

Common failures

• Starting with no drone experience
• Parts we could not buy locally
• Clone chips under the same name
• Uneven thrust from budget motors

Frame and propulsion assembly

Do the mechanical work first, so that faults show up before electronics are involved.

You need

F450 frame, motors, ESCs, screwdrivers, thread lock, soldering iron, heat shrink

Steps

1. Fasten the arms to the centre plates using thread-locked screws, keeping the frame square.
2. Bolt a motor to the end of each arm.
3. Mount an ESC on the middle of each arm, where propeller airflow will cool it.
4. Solder the three motor leads to the ESC and insulate every joint. You can fix spin direction later by swapping any two.
5. Route the ESC power leads to the power distribution board, keeping them away from where sensors will sit.

Check before moving on

• All screws are thread-locked and arms do not flex
• Every solder joint is insulated and pull-tested
• Propellers are not fitted

Common failures

• I2C bus freezing as motors spin up

Motor and ESC test using a spare ESP32

Prove the motors and ESCs on their own, before your flight controller and its firmware can be blamed for anything.

You need

A spare ESP32, a simple test sketch that outputs 1000 to 2000 µs PWM, multimeter

Steps

1. Connect each ESC signal line and a common ground to the ESP32.
2. Calibrate the ESCs so that all four recognise the same minimum and maximum. Follow the ESC manual for the sequence.
3. Drive one motor at a time at a low signal and check the direction. Swap two motor wires if it is wrong.
4. Set the directions to match the firmware: rear left and front right CCW, rear right and front left CW.
5. Run all four at several throttle levels and feel for heat at the ESCs, motors and power board.
6. Optional but useful: measure RPM on each motor with a magnet and Hall sensor at the same PWM. All four should match closely.

Check before moving on

• All four ESCs are calibrated to the same range
• Motor directions match the table
• No overheating at any test level
• All four motors spin at about the same speed at the same signal

Common failures

• Uneven thrust from budget motors

Flight controller board and power rails

A clean power rail is what stops sensors freezing when the motors spin up.

You need

Base PCB or breadboard for early tests, STM32H743VIT6 board, buck converter, capacitors, multimeter. See the schematics and pin tables

Steps

1. Set the MP1584 output to 5 V with a multimeter before connecting anything to it.
2. Feed the 5 V rail to the STM32 board and ESP32. Their onboard regulators supply 3.3 V to logic.
3. Solder ceramic and electrolytic capacitors right across VCC and GND at each sensitive sensor and at the STM32 rail.
4. Give the radio a stable 3.3 V supply, because it needs clean power at full transmit strength.
5. Wire the battery voltage divider to the ADC (4:1 in the firmware).
6. Wire the peripherals using the pin tables. Keep power leads away from the signal lines.
7. Power up without sensors first, and measure each rail.

Check before moving on

• The 5 V and 3.3 V rails read correctly under load
• Capacitors are fitted at sensors and at the STM32 rail
• No part gets warm when idle
• You have fixed the battery reading, or have a LiPo alarm and timer in use

Common failures

• I2C bus freezing as motors spin up

Flash the firmware

Now the flight controller gets its brain. The firmware boots, tests its sensors and refuses to arm until it has calibrated.

You need

PC, STM32CubeIDE v1.13 or newer, ST-Link, USB cable

Steps

1. Clone the project repository.
2. Open Aeronexus firmware/ as a project in STM32CubeIDE. The pin setup is in UAV_main_program.ioc.
3. Build, then flash through ST-Link on the SWD pins.
4. Connect USB. The board should appear as a virtual COM port.
5. Use the ST-Link debugger to watch live sensor values if something looks wrong.

Boot order: clocks → motors held off (1100 µs) → IMU init + calibration → I2C scan for magnetometer (0x0D, 0x1E, 0x2C)
            → barometer zero → UART interrupts → radio → load gains from flash → DISARMED → 250 Hz timer

Check before moving on

• Firmware builds and flashes without errors
• The USB COM port appears
• Sensors detected at boot, with the magnetometer's type identified
• The drone stays disarmed after boot, with motors silent

Common failures

• An ESP32 cannot be a flight controller
• Clone chips under the same name

Mount the sensors

Where a sensor sits decides how noisy it is. These physical steps do more than filtering can.

You need

3M closed-cell foam tape, 3D-printed mast, open-cell foam, twisted wire

Steps

1. Mount the flight controller at the balance point of the frame, on layers of foam tape instead of rigid standoffs. This stops motor vibration reaching the IMU.
2. Bolt the 3D-printed mast to the top deck and mount the magnetometer on it, away from motors, ESCs and power wiring.
3. Twist the magnetometer's I2C wires together and route them around the frame's edge, away from high-current leads.
4. Place a small piece of open-cell foam over the barometer's opening, to block propeller wash without sealing it.
5. Mount the radio and telemetry ESP32 on the lower deck. Solder the UART connection between the ESP32 and STM32, crossing TX to RX.

Check before moving on

• Flight controller is on foam at the balance point, facing the correct way
• Magnetometer is raised on its mast with twisted wiring
• Barometer has its foam cover
• Live sensor values stay stable when the frame is tapped lightly

Common failures

• I2C bus freezing as motors spin up

Build and program the transmitter

Your hands are part of the control system. This stage builds the link between you and the drone.

You need

ESP32 Devkit V1, 2 joysticks, ADS1115, SSD1306 OLED, nRF24L01+PA+LNA, 18650 cell with charging and regulation, Arduino IDE 2

Steps

1. Wire the ADS1115 and OLED to I2C (SDA 21, SCL 22) and the radio to SPI (SCK 18, MISO 19, MOSI 23, CE 4, CSN 5). Power the joysticks from 3.3 V.
2. Connect the joysticks to the ADC: A0 yaw, A1 throttle, A2 roll, A3 pitch.
3. In Arduino IDE, install RF24, Adafruit_ADS1X15, Adafruit_SSD1306 and Adafruit_GFX.
4. Open AMD24 mini transmitter/ESP32_Remote/ESP32_Remote.ino and flash it.
5. Release the sticks and read the raw centre values. Update ADC_YAW_MID, ADC_PITCH_MID and ADC_ROLL_MID to match your own joysticks, along with ADC_MAX if needed.
6. Confirm the display reads 0 at centre and that throttle runs from 1000 to 2000.
7. Power the flight controller and check that the signal indicator shows a link.

Check before moving on

• Yaw, pitch and roll read 0 when released, and ±500 at full stick
• Throttle reads 1000 at the bottom
• Moving a stick changes the matching axis, in the correct direction
• Radio link confirmed on the bench

Common failures

• Holding a hover by hand
• Radio range of about 100 m

Telemetry ESP32 and dashboard

This gives you eyes on the drone: live attitude, PID sliders and magnetometer calibration.

You need

ESP32-WROOM-32, PC with Node.js 18 or newer, a 2.4 GHz Wi-Fi network or hotspot

Steps

1. In Arduino IDE, install FastLED and open Aeronexus telemetry/ESP32_Telemetry.ino. Flash it.
2. Run the dashboard server, shown below. It serves the site on port 3000 and listens for the drone on TCP port 5000.
3. Change the default fleet admin password and drone PINs in the server code, before using a shared network.
4. With no saved Wi-Fi, the ESP32 starts its own Aeronexus-Setup network. Connect to it, then follow the setup in the dashboard's fleet page to send your Wi-Fi details and PC's IP address.
5. When the ESP32 reconnects, assign the new connection a drone name in the fleet page.
6. Alternatively, connect over USB. The server auto-detects the STM32 as a direct connection.
7. Tilt the frame by hand and watch the attitude display respond.

cd "Aeronexus dashboard"
npm install
npm start
# then open http://localhost:3000

Check before moving on

• Default passwords and PINs have been changed
• The dashboard shows live data
• Tilting the frame moves the attitude display the right way
• Telemetry returns on its own after a Wi-Fi drop

Balance and calibrate

The firmware assumes a balanced drone and accurate sensors. These steps make that true.

You need

String, bubble level, dashboard running

Steps

1. Balance: with everything installed, including the battery, hang the drone from its centre with string. Move the battery and modules until it hangs level in both directions. Mark the battery position.
2. IMU: place the drone on a level surface and keep it still at boot. The firmware averages 500 samples to find its offsets.
3. Magnetometer: open the dashboard's calibration panel. Slowly rotate the drone through all axes until the points form a sphere. Accept the offsets, which are saved to flash.
4. Keep the battery plugged in and all parts in final position during calibration, and stay away from large metal objects.
5. Check the compass heading against a phone compass. The firmware includes a local declination value, so update it for your location.

Check before moving on

• Drone hangs level on the string
• Attitude reads about 0° on a level surface
• Magnetometer points form a centred sphere after calibration
• Heading matches a reference compass

Common failures

• I2C bus freezing as motors spin up

Rig tuning

Starting gains are only estimates. A rig lets you find the limits with no risk of a crash.

You need

A sturdy wooden pivot rig, heavy anchor weights, the dashboard, a person dedicated to the disarm control

Steps

1. Direction test, propellers off. Arm and give about 30% throttle. Tilt the drone by hand. The motors on the low side must speed up, pushing that side back up. If the high side speeds up, stop and fix it before fitting propellers.
2. Build a rig that holds the drone firmly but allows it to rotate on one axis. Secure the rig so it cannot tip.
3. Fit propellers, checking direction on each motor. Keep everyone clear of the propeller disc. Never hold a drone by hand with propellers on.
4. Tune one axis at a time, with small changes. Start from the firmware defaults for roll and pitch: P 1.2, I 0.5, D 0.012.
5. P first: raise it until fast oscillation starts, then lower it by 10 to 15%.
6. D second: add it gradually until overshoot is damped. Back off if motors get hot or noisy.
7. I last: raise it carefully until the drone holds its angle against a steady push or offset.
8. Repeat for the other axis, then disarm and send the save command. Power-cycle and confirm the gains persisted.

Suggested safe ranges for this hardware, from the repository's tuning guide.

Check before moving on

• The low side speeds up in the direction test, on both axes
• Rig is secure and can't tip
• Roll and pitch both recover without oscillating
• Tuned gains survive a power cycle

Common failures

• No budget for a test bench

First liftoff

This is the riskiest step. Keep it short, low and boring.

You need

Open flat area, charged battery, timer, LiPo alarm, spotter, pre-flight checklist

Steps

1. Complete the whole pre-flight checklist.
2. Test the radio failsafe on the ground with propellers off: switch off the transmitter and confirm the drone disarms.
3. Stand well back, in the open, in daylight with low wind. No one stands in the flight path.
4. Arm using throttle down and yaw right held for 1 second, or from the dashboard.
5. Raise the throttle slowly until the drone lifts off a short distance, then land. Do not chase it with big corrections.
6. Review: if it drifts, oscillates or fights you, return to the rig and to stages 3, 9 and 10. Disarm with throttle down and yaw left.
7. Land by your timer, leaving a margin. Our safe flight time was about 5 to 7 minutes.

Check before moving on

• Go or no-go review done with the whole team
• Failsafe tested today
• Liftoff is level, with no strong drift
• Land within your battery limit

Common failures

• Uneven thrust from budget motors
• Holding a hover by hand

Survey test

Use the magnetometer as a sensor, and see what it can and cannot find.

You need

Known metal test object, open ground, survey page on the dashboard, GPS fix

Steps

1. Start on the ground. Move the drone by hand, powered with propellers off, over a known metal object, and watch the magnetic reading respond.
2. Open survey.html and capture a baseline, using the auto baseline to reduce the effect of outliers.
3. Check the GPS quality badge. The survey rejects points with poor GPS quality or at the wrong speed.
4. Walk or fly a low, slow pattern over the area, with the metal in a position you know.
5. Compare the map with the known position, then export the CSV for your records.
6. Only try lawnmower missions after manual flight is reliable. Keep a pilot ready to take over.

Check before moving on

• Reading changes clearly over the test object
• Baseline captured away from metal
• Anomaly appears in the rough area of the object
• Results recorded in your test log

Common failures

• Rough metal location