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Bluetooth Wireless Tuning from a PC

The MicoAir H743 V2 and the H743-Lite carry a small Bluetooth module on the board itself, wired internally to one of the flight controller's UARTs. Pair it with a computer and your ground station connects without a USB cable — which matters most in exactly the situations where a cable is inconvenient: the aircraft is assembled, the canopy is on, or it is sitting on the ground twenty metres away while you adjust something.

This guide covers connecting from a Windows PC. Connecting from an Android phone is covered in the H743 V2 manual.

This is for setup, not for flying

Bluetooth is a bench-and-field convenience. It is short range, it is not designed to fail gracefully, and it is not a control link. For telemetry in flight, use a proper radio such as the LR900.

How it works​

The thing to understand first, because it makes every later step obvious:

The Bluetooth chain from the flight controller UART to a COM port in the ground station

The module is a serial-to-Bluetooth bridge. The firmware has no idea Bluetooth is involved — it is talking MAVLink or MSP out of a UART, exactly as it would to a telemetry radio. On the other end, Windows turns the paired device into a virtual COM port, and the ground station opens that port like any other serial port.

So there is no "Bluetooth mode" to find in Mission Planner or INAV Configurator. You pick a COM port and a baud rate, and that is the whole configuration.

Step 1 — Power up and check the blue LED​

Power the flight controller, from a battery or over USB, and wait at least three seconds.

Look at the underside of the board for the blue Bluetooth power LED. If it is lit, the module is on and you can skip to pairing.

If it is dark, the module is switched off — not broken.

Hold the BOOT button for about two seconds to switch it on. Holding it again switches it back off.

The power state is remembered across power cycles

This is the single biggest source of "my Bluetooth does not work" reports. The module's on/off state is stored, so a board that was switched off in a previous session comes back switched off, and every scan finds nothing. Check the blue LED before concluding anything else is wrong.

The board's exact LED positions are in the H743 V2 manual.

Step 2 — Pair from Windows​

First, confirm the computer has Bluetooth at all. Most laptops do. Desktops depend on the motherboard or wireless card; a USB Bluetooth adapter works fine if not.

  1. Open Settings → Bluetooth & devices and make sure Bluetooth is on.
  2. Click Add device.
  3. Choose Bluetooth.
  4. Click "Show all devices".
  5. Select the entry named MicoAir743v2-xxxxxx (H743 V2) or MicoAir743Li-xxxxxx (H743-Lite), where the last part varies per board.

Windows adds it as a paired device. No PIN is needed.

"Show all devices" is not optional

The add-device dialogue normally lists only the categories Windows recognises — audio, mice, keyboards, displays. A serial Bluetooth device is not one of them, so the flight controller does not appear until you ask for everything. This step is skipped constantly and looks exactly like the board not being discoverable.

Step 3 — Find the COM port​

Open Device Manager. The flight controller now appears twice:

  • Under Bluetooth, as the paired device.
  • Under Ports (COM & LPT), as a virtual serial port — for example COM7.

The port number under Ports is the one you need. Note it down.

Windows sometimes creates two ports for one Bluetooth device, an outgoing and an incoming one. The outgoing port is the one that works; if you have two and the first fails to connect, try the other.

Step 4 — Connect from your ground station​

Whichever software you use, the settings are the same: that COM port, at 115200 baud.

Mission Planner — ArduPilot​

  1. Select the Bluetooth COM port in the drop-down at the top right.
  2. Set the baud rate to 115200.
  3. Click CONNECT.

It takes a few seconds to download the parameter list, and rather longer than USB would.

QGroundControl — ArduPilot or PX4​

QGroundControl does not scan serial ports automatically for this, so the link is defined once and then reused.

  1. Application Settings → Comm Links.
  2. Click Add.
  3. Give it a name, set the type to Serial, choose the Bluetooth COM port, and set the baud rate to 115200.
  4. Click OK.
  5. Select the link you just created and click Connect.
  6. Return to the main screen. It loads parameters automatically, usually within a few seconds.

INAV Configurator — INAV​

  1. Select the Bluetooth COM port at the top right.
  2. Set the baud rate to 115200.
  3. Click Connect.

Step 5 — Check the green LED​

Below the blue power LED there is a green connection LED.

BlueGreenMeaning
offoffthe Bluetooth module is switched off — hold BOOT
onoffpowered and discoverable, but nothing is connected
onona ground station has an open link

Pairing alone does not light the green LED. Only an actual connection from a ground station does, and it goes out again when the software disconnects or closes. That makes it a useful diagnostic: if you are paired but green never lights, the problem is between the COM port and your ground station, not with the pairing.

Which UART it uses​

The Bluetooth module is wired internally to UART8 at 115200 baud, and the firmware ships configured to match — so under normal circumstances there is nothing to set.

On ArduPilot that port is SERIAL8. If a connection that used to work has stopped, this is worth checking: reassigning SERIAL8 to something else, or changing its baud rate, disconnects Bluetooth.

UART8 being occupied also means it is not available for anything else. The H743 V2 manual has the full UART map.

Easily confused points​

Bluetooth appears as a COM port. There is no Bluetooth option to look for in the ground station.

The module's power state survives a power cycle. Off stays off until you press BOOT.

"Show all devices" is required in the Windows add-device dialogue.

Paired is not connected. Blue means powered; green means a ground station is on the line.

115200 is not negotiable — it is what the module runs at.

Two COM ports can appear for one device. Try the other if the first will not open.

Troubleshooting​

SymptomWhere to look
Nothing found when scanningBlue LED. Hold BOOT for two seconds. Then check you clicked "Show all devices".
Paired, but no COM port in Device ManagerRemove the device in Windows and pair it again.
COM port exists but will not openAnother program already has it. Close other ground stations and serial terminals.
Connects and immediately dropsBaud rate is not 115200, or SERIAL8 has been reassigned.
Connects but parameters load very slowlyNormal — Bluetooth is much slower than USB. Move the computer closer.
Green LED never lightsThe link is not being opened. Try the other COM port if there are two.
Worked yesterday, not todayThe module was switched off with BOOT, or the state was toggled by accident.

Where to buy​

Written and maintained by the Robofusion engineering team.