Free · interactive lesson
FPV build workshop: assemble and set up a 5" drone step by step
Build a real FPV drone in your browser: pick the parts, mount them on the frame, solder every wire to its pad, set up Betaflight and run the checks before the first flight. If you connect something wrong, it tells you what would have happened, from “it would not work” to “it would have burnt”.
The lesson drone is the AIRLAB FPV Mario 5, built and flown for real. The flight controller pads are shown as a simplified diagram (not to scale): before soldering yours, always check your board’s manual.
What you learn in the workshop
Choosing parts
Why a 3–6S stack and not a 4S one, what KV a 5" needs on 6S, which receiver talks to your ELRS radio and which video unit handles battery voltage.
Assembly and soldering
Motors in their corners in Betaflight order, capacitor with the right polarity, XT60, receiver and GPS with TX and RX crossed, DJI connector and buzzer.
Betaflight setup
Ports, CRSF receiver, DShot600 bidirectional and RPM filter, props out, modes, failsafe with GPS Rescue, HD OSD for the O4 and calibration.
Testing before flight
Magnifier and multimeter, smoke stopper, motor test with props off, arming disable flags and props on the right way round.
The lesson drone: Mario 5
| Part | Model | What matters |
|---|---|---|
| Frame | SpeedyBee Mario 5 | True-X 5", 30×30 and 20×20 stack |
| FC + ESC | SpeedyBee F405 V4 + BLS 60A | 3–6S, 60 A per motor (80 A burst for 10 s), 1000 µF 35 V capacitor |
| Motors | T-Motor Velox V3 2207 1750KV | ~1.35 kg thrust per motor on 6S (official thrust report) |
| Video | DJI O4 Air Unit Pro | 7.4–26.4 V, two antennas; on the FC’s DJI connector (9 V and UART1) |
| Receiver | Radiomaster RP1 V2 (ELRS 2.4 GHz) | CRSF on UART2 (T2/R2) |
| GPS | HGLRC M100-5883 (M10 + compass) | UART6 (T6/R6), 4V5 and compass on SDA/SCL |
| Buzzer | Vifly Finder 2 | BZ+ / BZ−, with its own battery |
| Battery | Tattu R-Line V3 6S 1300 mAh | ~210 g; 695 g ready to fly, TWR 7.9:1 |
SpeedyBee F405 V4 port map
| UART | Pads | On the Mario 5 | In Betaflight (Ports) |
|---|---|---|---|
| UART1 | T1/R1 and 6-pin DJI connector | DJI O4 Air Unit Pro | Peripherals: VTX (MSP + DisplayPort) |
| UART2 | T2/R2 (and the SBUS pin) | ELRS receiver RP1 V2 | Serial RX (CRSF provider) |
| UART3 | T3/R3 | Free | — |
| UART4 | No pads | Onboard Bluetooth | MSP at 115200 (SpeedyBee app) |
| UART5 | R5 (RX only) | ESC telemetry | — |
| UART6 | T6/R6, next to 4V5, SDA and SCL | M10 GPS with compass | Sensor input: GPS |
With an external receiver, the stack manual says to remove, or cut and insulate, the SBUS wire in the DJI cable: that pin goes to R2, the same pad the receiver uses.
The mistakes that burn the most electronics
Reversed polarity
A reversed XT60 or capacitor burns the ESC the moment you plug in the battery. Check with a multimeter before plugging anything in.
Wrong voltage
A 4S stack on 6S, or a standard O4 (3.7–13.2 V) on battery voltage. Always check each part’s voltage range.
Shorts from solder or screws
A solder bridge between two phases, or a motor screw that is too long and touches the windings. Magnifier and smoke stopper on first power-up.
TX to TX
Nothing burns, but it does not work: on a UART one side’s TX goes to the other’s RX. The compass is the opposite: SDA to SDA and SCL to SCL.
Sources
Questions
Is the workshop free?
Yes. It runs in your browser, with no sign-up, and saves your progress in your own browser so you can carry on another day.
Does it work for a drone other than the Mario 5?
The lesson uses the Mario 5, but what it teaches applies to almost any 5" on Betaflight: crossing UARTs, powering each part at its voltage, the Ports tab, CRSF, DShot, props out, failsafe and the checks before first power-up. Pads and UARTs change from board to board: always check your board’s manual.
Which UART do I use for the GPS on the SpeedyBee F405 V4?
UART6 (T6/R6). The Betaflight wiki groups it with 4V5, SDA and SCL precisely for a GPS with compass, and 4V5 also works with USB plugged in, so you can see satellites without a battery.
How do I connect a DJI O4 Air Unit Pro to the F405 V4?
With the 6-pin cable to the FC’s DJI connector: it carries 9 V, ground and UART1. In Betaflight, under Ports, set UART1 to “VTX (MSP + DisplayPort)” and the OSD video format to HD. If you use an ELRS receiver, remove the SBUS wire from the cable.
Why won’t my drone arm in Betaflight?
Betaflight shows the reasons: MSP (configurator connected over USB), THROTTLE (throttle above minimum), ANGLE (quad tilted), ARMSWITCH (arm switch on at power-up), RXLOSS (no receiver signal)… In the workshop you clear them one by one.
Can I then fly the drone I built?
Yes: at the end, the “Fly the Mario 5 in the simulator” button opens the AIRLAB FPV simulator with the same drone, with its weight, motors and battery.