Tiny Quadcopter (Part 2)

See previous post.

Programming via DFU worked fine, and USB serial also worked, after I added stm32f411 to the list of supported devices in stm32f4xx_hal. I should just check that serial echo example works and submit a pull request: so far I've only tried printing messages.

This means I can definitely use my STM32F411 board without soldering any headers onto it, which keeps it small and lite.

I've updated my project to use that board for the receiver, and a STM32F103 black pill for the transmitter.

I now have a dilemma re NRF24L01+ boards. There are a few variables:

  • With, or without RFX2401 range extender. The main issue is they draw 90mA during TX. The on board 3.3V regulator on the micro-controller board can't handle that and neither can the 5V output of the flight controller, so I would have to add a dedicated regulator, powered directly from the battery. It also draws 8mA in receive mode.
  • Standard header vs 1.27mm edge connectors: the boards with the latter also have miniature SMD crystals, which make them much smaller and lighter. The standard header connectors are really too big to fit on the quadcopter.
  • One of external antenna connector, internal trace antenna, chip antenna.


There are all combinations of the above, but what I have right now is


  • w/ range extender + compact connector + chip antenna
  • w/o range extender + large connector + trace antenna
  • w/o range extender + large connector + external antenna (only one of these, and I haven't found a place to buy more of them).

I didn't realise what the board with the range extender was.

Some boards w/o range extender + compact connector + trace antenna will arrive some when from China. These seem like the best solution for the receiver, but I might be too impatient.

I've actually partly built a transmitter using an NRF24L01+ without a range extender, which is not ideal, so perhaps I'll start again on that front.





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