Flight Controller

The flight controller (FC) is the brain of your drone. It reads sensor data (gyroscope, accelerometer), processes your stick inputs, runs PID loops, and sends commands to the ESCs. Every other component connects to or through the FC.

Choosing an FC

Processor

Processor	Speed	Features	Price	Notes
F4	168MHz	Basic, limited UARTs	Budget	Adequate for simple builds, being phased out
F7	216MHz	More UARTs, faster processing	Mid	The current standard. Handles all modern features.
H7	480MHz	Maximum performance, most UARTs	Premium	Overkill for most pilots. Future-proof.

F7 is the recommendation for new builds. It handles everything modern Betaflight needs with room to spare.

Form Factor

• 30.5x30.5mm: Standard for 5” builds. Most options.
• 20x20mm: Compact. For sub-250g, 3” builds, and tight frames.
• AIO (All-in-One): FC + ESC on one board. For micro builds and whoops.

Key Features to Look For

• Barometer: For altitude hold (useful with GPS)
• Blackbox flash: On-board flash memory for flight logging. 16MB+ preferred.
• SD card slot: For extended Blackbox logging
• Current sensor: For battery monitoring (often on the 4-in-1 ESC instead)
• Number of UARTs: Each UART connects a serial device (receiver, GPS, VTX control, Bluetooth, etc.). 4+ UARTs is comfortable. F7/H7 typically have 5-7.

Popular FCs (2025-2026)

FC	Processor	Size	Notes
SpeedyBee F405 V4	F4	30.5mm	Budget, feature-rich for F4
SpeedyBee F7 V3	F7	30.5mm	Great value F7
Matek F722-SE	F7	30.5mm	Proven, reliable
Diatone Mamba F7	F7	30.5mm	Good feature set
BetaFPV F722 AIO	F7	25.5/20mm	Whoop and micro

Installation

Stack Mounting

The FC mounts on standoffs above the 4-in-1 ESC, forming a “stack”:

1. Bottom: Frame bottom plate
2. Standoffs (usually M3, 5-8mm tall)
3. 4-in-1 ESC: First board in the stack
4. More standoffs
5. Flight Controller: Second board
6. Optional: VTX on top (if stack-mounted)
7. Top standoffs + top plate

Use rubber grommets (soft-mounting) between the FC and the standoffs. This dampens vibration from reaching the gyro — critical for clean flight data and good PID performance.

Orientation

The FC has an arrow marking (or a labeled “front” direction). This must match the drone’s forward direction. If you mount it at a different angle (due to frame constraints), set the board alignment offset in Betaflight Configuration tab:

• 90° rotated clockwise: Set yaw offset to 90°
• 180° rotated: Set yaw offset to 180°
• etc.

Wiring

The FC is the central hub. Everything connects to it:

Connection	Pads	Notes
ESC	Usually via stack connector or solder pads	Motor signals + power
Receiver	UART TX/RX + 5V + GND	Serial receiver (CRSF, SBUS)
VTX	Video pad + UART (SmartAudio) + power	Analog: video wire. Digital: ribbon/coax.
Camera	Video in (analog) or N/A (digital)	Analog cameras wire to VTX, not FC
GPS	UART TX/RX + 5V + GND	If using GPS module
LED strip	LED pad + 5V + GND	Addressable LEDs
Buzzer	BZ+ and BZ-	For lost drone beeper
USB	USB-C port	Configuration and firmware flashing

Soldering the FC

1. Plan your wiring before soldering anything. Know which UART each peripheral uses.
2. Tin all pads first — apply a small dome of solder to each pad you’ll use.
3. Use flux on small pads (UARTs are tiny)
4. Keep signal wires short — longer wires pick up noise
5. Route wires cleanly — avoid crossing over the gyro chip (center of the FC)
6. Don’t bridge pads — UART pads are close together. Use a fine-tip iron and thin solder.

First-Time Setup

After mounting and wiring:

1. Connect USB (no battery, no props)
2. Open Betaflight Configurator
3. Flash the latest Betaflight firmware for your FC target
4. Configure Ports (which UART does what)
5. Configure receiver protocol
6. Configure motor protocol (DShot600)
7. Verify motor order and direction in the Motors tab (props off!)
8. Set up OSD
9. Configure failsafe
10. Set rates and modes

→ See Betaflight Setup for the full step-by-step walkthrough.

Troubleshooting

Problem	Likely Cause	Fix
FC not detected on USB	Driver issue	Install ImpulseRC Driver Fixer (Windows) or check cable
FC won’t flash firmware	Wrong target selected	Check FC documentation for exact target name
Gyro not working	Bad soft mount or gyro damage	Check connections, try removing grommets to test
Random reboot in flight	Power brownout	Add capacitor, check BEC capacity
Smoke on power-up	Wiring short	Disconnect immediately. Use a smoke stopper next time. Check all connections.