# Holybro Pixfalcon

:::warning This flight controller has been [discontinued](../autopilot_experimental) and is no longer commercially available. :::

:::warning PX4 does not manufacture this (or any) autopilot. Contact the [manufacturer](https://holybro.com/) for hardware support or compliance issues. :::

The Pixfalcon autopilot (designed by [Holybro®](https://holybro.com/)) is binary-compatible (FMUv2) derivative of the [Pixhawk 1](pixhawk) design that has been optimized for space-constrained applications such as FPV racers. It has less IO to allow for the reduction in size.

![Pixfalcon hero image](https://4155462212-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LArEa7z2SPawfl3HpCD%2Fuploads%2Fgit-blob-6e11e78efcc06fa415420d5c6fac9fa469c87ebb%2Fhardware-pixfalcon.png?alt=media)

## Quick Summary

* Main System-on-Chip: [STM32F427](http://www.st.com/web/en/catalog/mmc/FM141/SC1169/SS1577/LN1789)
  * CPU: 180 MHz ARM® Cortex® M4 with single-precision FPU
  * RAM: 256 KB SRAM (L1)
* Failsafe System-on-Chip: STM32F100
  * CPU: 24 MHz ARM Cortex M3
  * RAM: 8 KB SRAM
* GPS: u-blox® M8 (bundled)

### Connectivity

* 1x I2C
* 2x UART (one for Telemetry / OSD, no flow control)
* 8x PWM with manual override
* S.BUS / PPM input

## Availability:

From distributor [Hobbyking®](https://hobbyking.com/en_us/pixfalcon-micro-px4-autopilot-plus-micro-m8n-gps-and-mega-pbd-power-module.html)

Optional hardware:

* Optical flow: PX4 Flow unit from manufacturer [Holybro](https://holybro.com/products/px4flow)
* Digital Airspeed sensor from manufacturer [Holybro](https://holybro.com/products/digital-air-speed-sensor) or distributor [Hobbyking](https://hobbyking.com/en_us/hkpilot-32-digital-air-speed-sensor-and-pitot-tube-set.html)
* On screen display with integrated Telemetry:
  * [Hobbyking OSD + EU Telemetry (433 MHz)](https://hobbyking.com/en_us/micro-hkpilot-telemetry-radio-module-with-on-screen-display-osd-unit-433mhz.html)
* Pure Telemetry options:
  * [Hobbyking Wifi Telemetry](https://hobbyking.com/en_us/apm-pixhawk-wireless-wifi-radio-module.html)
  * [SIK Radios](../../peripherals/telemetry/sik_radio)

## Building Firmware

:::tip Most users will not need to build this firmware! It is pre-built and automatically installed by _QGroundControl_ when appropriate hardware is connected. :::

To [build PX4](../../../development/getting_started/building_px4) for this target:

```
make px4_fmu-v2_default
```

## Debug Port

This board does not have a debug port (i.e it does not have a port for accessing the [System Console](../../../development/debug/consoles/system_console) or the [SWD interface](../../../development/debug/gdb_debugging/swd_debug) (JTAG).

Developers will need to solder wires to the board test pads for SWD, and to the STM32F4 (IC) TX and RX to get a console.

## Serial Port Mapping

| UART   | Device     | Port                     |
| ------ | ---------- | ------------------------ |
| UART1  | /dev/ttyS0 | IO Debug                 |
| USART2 | /dev/ttyS1 | TELEM1 (No flow control) |
| UART4  | /dev/ttyS2 | GPS                      |
