Omnibus F4 Nano v6.1 pinout

A colleague has acquired a number of Omnibus F4 Nano v6.1 boards like this GetFPV page:

We were able to flash AP bootloaders on them with dfu-util, and install ArduCopter on them. We’ve run into some difficulty finding where the different serial ports come out, and Google turns up surprisingly little. (There are many threads about similar boards from the same vendor, but with different pinouts).

What works:

  • Connecting to Mission Planner over USB
  • Controlling all 4 ESCs
  • GPS
  • SBUS
  • Telemetry (only if configured on SERIAL3 instead of the GPS

What we need help with:

  • Finding SERIAL1 or SERAIL2 so we can have telemetry and GPS at the same time.

Who is selling them without pinout documentation? The one from is not completely accurate anyway. So far I’ve only confirmed power and ground pads but I’ve already found errors.

Note that the 5v in red seems to be the BEC while the others seem to be the normal 5V supply.
The pin marked GND near the F.Port pin is not a ground pin. It seems to be a driver, perhaps inverted TX6?


The pin marked GND that you crossed out shorts to RX3.


Can you clarify what you mean by “normal 5V supply?”


The Version 6 board had two 5 V supplies, one labeled 5V, and one higher current supply labeled 5VDC which, I believe was a separate 2A supply. The one I colored red is slightly higher voltage than the rest of the 5V pins so I think it is the separate supply.

Also, that pin is not supplied when powered only from USB

Any idea why they did that?

No, but the vendor confirmed that the documentation is wrong and they are updating it. They also pointed out that RX4 is one of the pins on the ESC connector and breaks out to a pad.


Yes, I noticed that as well. The Ardupilot hwdef.dat for the V6 board also documents ESC sensor as UART4_RX. It’s a nice layout in that it provides access to the pads for the current sensor and ESC telemetry pins even if you use the connector instead of the motor PWM pads.

So my problem is that I want two full serial ports, 9ne for GPS and one for telemetry radio. I have UART6 on the back that I can use for either, but I need another one. RX3/TX3 in the top row go to I2C for compass, so can’t use that.


Can’t you use RX/TX1 for Telemetry?

might be a good idea to add USART3 on PB10 / 11 as an alternative config option.

The V6 hwdef says those pins are already used for I2C2, which I’m guessing are used internally on the board.

Sorry. Ignore that. Of course, they are connected to the RX3 and TX3 pads. Yes, your pull request could be very useful if an I2C compass is not used.

@vierfuffzig, As long as you are adding flexibility, it would be nice to have GPIO or PWM(5) and PWM(6) on PB9 (CAM_C pad) and PA2 (Smart Audio pad) as well. I use these pins on one of my V6 builds for a Firefly 4K split camera which can be controlled by two relay (logic) signals, but I think this board could support a hexa frame as well.

Speaking of alternate use, I don’t use the LED pad (PB6) for anything since I use a TBS CF receiver and combine Telemetry and RC control on RX/TX1. May as well allow the original purpose of GPIO here too. I haven’t checked if this pin could be used for anything else.

This is where sbus input is. Isn’t RX1 inverted to allow RC input? If I use USART1 for telemetry, where should I connect the RC RX?


Ardupilot normally uses the LED pad for RC input on the V6 board. It should be the same for V6.1, the pad is marked ws2812 on the V6.1 diagram.

The WS2812 pad goes directly to an STM32 pin where one of the alternative functions is USART1_RX. I can’t remember the pin number, I can check when I get home. The pin marked SBUS(RX1) does not connect directly to an STM32 pin. It may be going through a buffer or inverter.


i‘m not 100% positive about the alt() config system working for repurposing pins as PWM as well. this was mentioned on discord recently and afaik it isn‘t featured yet. for now you‘d likely have to build an individualized fw.

if you don‘t need I2C, you might use RCIn via UART to free the LED pin for alternative timer use. that being said, i haven‘t taken a closer look at the F405’s alt functions chart respectively…

The pad marked “WS8212” rings to pin 58 on the uC, with is PB6. The functions available on this pin are:

  • I2C1_SCL
  • TIM4_CH1
  • CAN2_TX
  • DCMI_D5