Last updated
Last updated
:::warning This flight controller has been and is no longer commercially available. :::
:::warning PX4 does not manufacture this (or any) autopilot. Contact the manufacturer for support or compliance issues. :::
The Omnibus F4 SD is a controller board designed for racers. In contrast to a typical racer board it has some additional features, such as an SD card and a faster CPU.
These are the main differences compared to a :
Lower price
Fewer IO ports (though it's still possible to attach a GPS or a Flow sensor for example)
Requires external pull up resistor on the I2C bus for external GPS, see below.
Less RAM (192 KB vs. 256 KB) and FLASH (1 MB vs. 2 MB)
Same board dimensions as a Pixracer, but slightly smaller form factor (because it has less connectors)
Integrated OSD (not yet implemented in software)
:::tip All the usual PX4 features can still be used for your racer! :::
:::note This flight controller is . :::
Main System-on-Chip:
CPU: 168 MHz ARM Cortex M4 with single-precision FPU
RAM: 192 KB SRAM
FLASH: 1 MB
Standard racer form factor: 36x36 mm with standard 30.5 mm hole pattern
MPU6000 Accel / Gyro
BMP280 Baro (not all boards have it mounted)
microSD (for logging)
Futaba S.BUS and S.BUS2 / Spektrum DSM2 and DSMX / Graupner SUMD / PPM input / Yuneec ST24
OneShot PWM out (configurable)
Built-in current sensor
Built-in OSD chip (AB7456 via SPI)
The board is produced by different vendors, with some variations (e.g. with or without a barometer).
:::tip PX4 is compatible with boards that support the Betaflight OMNIBUSF4SD target (if OMNIBUSF4SD is present on the product page the board should work with PX4). :::
:::tip Any Omnibus F4 labeled derivative (e.g. clone) should work as well. However, power distribution on these boards is of varying quality. :::
These are the boards tested and known to work:
Purchase from:
Original Airbot Omnibus F4 SD
Purchase from:
Accessories include:
Boards from different vendors (based on this design) can have significantly different layout. Layouts/Silkscreens for various versions are shown below.
Below are silkscreens for the Airbot Omnibus F4 SD (V1), showing both top and bottom.
Below are silkscreens for the Hobbywing XRotor Flight Controller F4.
RC is connected to one of the following ports:
UART1
SBUS/PPM port (via inverter, internally goes to UART1)
:::note Some Omnibus F4 boards have a jumper connecting either or both the MCU SBUS and PPM to a single pin header. Set your jumper or solder bridge to the appropriate MCU pin before use. :::
UART6: GPS port
TX: MCU pin PC6
RX: MCU pin PC7
Airbot Omnibus F4 SD Pinout is on Port J10 (TX6/RX6):
UART4
TX: MCU pin PA0
RX: MCU pin PA1
57600 baud
This can be configured as the TELEM 2 port.
Airbot Omnibus F4 SD Pinout:
TX: RSSI pin
RX: PWM out 5
There is one I2C port available via:
SCL: MCU pin PB10 (might be labeled as TX3)
SDA: MCU pin PB11 (might be labeled as RX3)
:::note You will need external pullups on both signals (clock and data). You can use 2.2k pullups for example to attach an external mag. :::
Here is an example implementation. I used a Spektrum plug to get 3.3v from the DSM port, connecting only 3.3v + to each line via 2.2k resistor.
Only a single UART is needed for RC and telemetry.
The CRSF protocol is optimized for low latency.
150 Hz RC update rate.
The signals are uninverted and thus no (external) inverter logic is required.
:::note If you use CRSF Telemetry you will need to build custom PX4 firmware. By contrast, FrSky telemetry can use prebuilt firmware. :::
:::note The referenced links above contains the documentation for the TX/RX modules. :::
Connect the Nano RX and Omnibus pins as shown:
You can use either pre-built firmware or your own custom firmware.
The firmware can be installed in any of the normal ways:
Build and upload the source
:::note This board fits on top of the without soldering. This ESC board also provides power for the Omnibus board. :::
(getfpv)
for MAVLink telemetry. You need to connect these pins: GND, RX, TX, VCC and CH-PD (CH-PD to 3.3V). The baud rate is 921600.
Airbot Omnibus F4 SD Pinout is on Port J10 (SCL [clock] / SCA [data]):
The Omnibus supports telemetry to the RC Transmitter using or .
may be used to send telemetry data from the flight controller (the vehicle's attitude, battery, flight mode and GPS data) to an RC transmitter such as a Taranis.
Benefits over include:
For Omnibus we recommend the , since it is specifically designed for small Quads.
On the handheld controller (e.g. Taranis) you will also need a . This can be plugged into the back of the RC controller.
Next update the TX/RX modules to use the CRSF protocol and set up telemetry. Instructions for this are provided in the (search for 'Setting up radio for CRSF').
You will need to build custom firmware to use CRSF. For more information see .
The schematics are provided by : .
The board comes pre-installed with . Before PX4 firmware can be installed, the PX4 bootloader must be flashed. Download the bootloader binary and read for flashing instructions.
To for this target:
:::warning If you use in your radio system, as describe above, then you must use custom firmware. :::
using QGroundControl.
In addition to the , the following parameters are important:
provides a good overview with pinouts and setup instructions.
USART1
/dev/ttyS0
SerialRX
USART4
/dev/ttyS1
TELEM1
USART6
/dev/ttyS2
GPS
TX
Ch2
RX
Ch1
This should be disabled since the board does not have an internal mag. You can enable it if you attach an external mag.
Disable this if your board does not have a barometer.
