Rotorflight dongle

The phone app on any Rotorflight helicopter, whatever receiver flies it

Flash a chip from your browser

Plug a Seeed XIAO ESP32-S3 into this computer with a USB-C cable and press the button. The browser writes the firmware straight into the chip — nothing to install, no command line, no files to download and keep in order.

1. Put the board into flashing mode

Hold down B, tap R, then let go of B. The two tiny buttons are beside the USB socket.

You will know it worked: the yellow light goes out. A red light may stay on or flicker — that is the battery charger, not the firmware; ignore it. If the yellow one is still lit, it did not take: do it again, holding B a little longer.

Do this every time, even on a brand-new board. It costs a second and it always works — whereas skipping it fails on any board that already has our firmware, because the firmware takes the USB socket over for its own use and the board stops offering a port at all.

2. Click

The first time on a computer, the browser asks permission to reach the chip — there will be just one thing in the list; choose it. After that it remembers, and there is nothing to choose. It writes for about a minute. Leave it alone until it says it has finished.

 

If it says no chip was found, the board is not in flashing mode, or the cable is the wrong sort. Do the B and R buttons again and press the button once more. If it still will not appear, try another USB-C cable: many short leads carry power only, so the board’s orange light comes on but nothing else happens.

This is also how you start again. It erases everything first, so a board that is already in use, or confused, or that you simply want to hand on to somebody else, comes back exactly as a new one would. There is no separate wipe button because there is no need for one: this is it. Day to day you would never come here at all — a working board updates itself over the air from the phone app.

Then what?

  1. Attach the aerial — the little one in the box, pressed onto the tiny gold socket on top of the board. Without it the board works only from an arm’s length away. Easy to forget.
  2. Unplug it and plug it back in. The chip does not restart by itself after flashing; it sits waiting until the power goes away and comes back. The USB port then goes quiet — that is normal, and not a sign of failure.
  3. Name it from the phone app, over Bluetooth. Open the app, tap Connect, and the new board is in the list as Untitled. Its front page asks you to rename it — do, as soon as you can: two boards with the same name cannot be told apart. It restarts under the new name.
  4. Or by WiFi: the board raises its own network, called Untitled. Join it from a computer and open 192.168.4.1. Not from a phone: the little window a phone pops up when you join a network is a cut-down browser, and it drops the network again the moment it decides there is no internet.
  5. There is nothing to configure. A board with no radio chips on it works out what it is: wired to a flight controller it becomes a dongle; fed a receiver’s signal on D5 it becomes a simulator interface.
  6. After this it updates itself, over the air. You should not need a cable again.

The four wires, and which pin goes where, are on the dongle page. The whole thing is open source: github.com/Mmessiter/LDRC_V2.

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