Board Layout
Form Factor
The 305ap uses a 30.5 mm × 30.5 mm mounting pattern, matching standard 30.5 mm stack flight controllers. It is compatible with most 5" and larger freestyle/racing frames as well as custom mounts.
Connector Placement
The 305ap connector layout is designed for clean wire routing in a typical FPV stack:
| Connector | Location | Function |
|---|---|---|
| USB-C | Side edge | USB 2.0 FS programming and GCS connection |
| Motors | Bottom | 8× PWM/DSHOT outputs + ESC telemetry + current sense |
| TELEM1 | Side/top | 6-pin JST-GH, UART4 with CTS/RTS |
| TELEM2 | Side/top | 6-pin JST-GH, UART7 with CTS/RTS |
| GPS | Side | 6-pin JST-GH, USART6 + I2C4 |
| CAN1 | Side | 4-pin JST-GH, FDCAN1 |
| CAN2 | Side | 4-pin JST-GH, FDCAN2 |
| RC IN | Side | 3-pin, single-wire (SBUS/CRSF/PPM) |
| VTX | Side | 6-pin JST-GH, 9 V + UART2 + SBUS out |
| External I2C | Side | 4-pin JST-GH |
| External SPI | Side | 7-pin JST-GH |
| microSD | Bottom | Push-push slot, card detect supported |
Top Side
- STM32H743VIH6 MCU (TFBGA100)
- 2× IMU slots (SPI2, SPI3) — ST LSM6DSV or TDK InvenSense ICM-45686, auto-detected at boot
- BMP581 barometer (SPI)
- MMC5983MA magnetometer (I2C, internal)
- SIT1044T CAN transceivers
- Status LEDs (red, green, blue)
- BOOT and RESET buttons
Bottom Side
- Power components (AP63357 buck converters, LM74700-Q1, TPS2116, RT9193 LDO)
- RGB LED
- Motor output connector (U21)
- Voltage/current sense frontend (TLV9002)
- SMAJ30CA TVS, AON7246E FET
- microSD slot
Mounting
The 305ap uses the standard 30.5 mm × 30.5 mm M3 hole pattern. Mounting holes have a 3 mm clearance diameter and accept fasteners with heads up to 6 mm across. The mounting holes are electrically connected to GND — use nylon standoffs or insulating washers if GND continuity to the frame is not desired.
The board is a single-MCU architecture with no FMU/I/O split. All outputs and peripherals are driven directly by the STM32H743.
Fastener selection
Connectors are densely packed near the board edges, leaving little room to access or torque fasteners from above. Hex-socket bolt heads (like M3 cap screws) are awkward to reach with an Allen key in this layout. Preferred options:
- Screw-style fastener heads (slotted or Phillips M3 screws) — a screwdriver accesses the head from above without needing the lateral clearance that an Allen key requires
- Rubber anti-vibration standoffs — the raised profile lifts a bolt head above the board surface and clear of the surrounding connectors, providing enough room to tighten
Soft-mount the FC using rubber standoffs (M3 anti-vibration grommets) for best IMU performance. Both supported IMU parts have good vibration immunity, but excessive airframe resonance will still degrade EKF2 estimation.
Buttons
| Button | Function |
|---|---|
| BOOT | Hold at power-on to enter DFU bootloader mode |
| RESET | Hard reset the MCU |
To enter DFU mode for flashing: hold BOOT, apply power (or press RESET while powered), then release BOOT. The board will enumerate as a DFU device over USB.
LEDs
See Troubleshooting → LED Status for a full LED code reference.
| LED | GPIO | PX4 Function |
|---|---|---|
| Red | PD9 | Errors, boot state |
| Green | PB12 | GPS lock, armed state |
| Blue | PE12 | Flight mode indicator |
| RGB | — | Full status (arming, modes, errors) |
Active-low: GPIO LOW = LED on.