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MicoAssistant Guide

MicoAssistant is the configuration tool for MicoAir telemetry radios, optical flow sensors and rangefinders. It runs in a browser — nothing to install — and it does three jobs: identify what is plugged in, read and write its parameters, and show live sensor data.

Open MicoAssistant →

It works in Chrome or Edge, because it uses the Web Serial API to reach the serial port and other browsers do not implement it.

This guide covers getting connected, which is where the difficulty actually lies. What each parameter means is in the individual product manuals, linked at the end.

Getting connected​

Four things have to be right, and they fail in that order: wiring → driver → port → baud rate. Working through them in order saves a great deal of time, because each one makes the next testable.

Plug it in​

Decision tree: USB-C devices connect directly, UART devices need an adapter, and the driver always follows the chip

If the device has a USB-C socket, use it. The LR900, LR868, LR24-F and LR24-P, and the TRS all do. There is no wiring to get wrong, and the conversion chip is inside the device.

If the device only has a UART, it needs a USB-to-TTL adapter. That covers the MTF optical flow sensors, the MT rangefinders, and the LR24-F-Mini, which has no USB socket of its own.

Device pinAdapter pinWhy
TXRXtransmit on one side is receive on the other
RXTXlikewise, the other way
GNDGNDboth ends need a common reference
VCCmatching supplycheck the device's own voltage requirement
Set the adapter to 3.3 V

MicoAir sensors and modules use 3.3 V serial logic. Many USB-to-TTL adapters have a 5 V / 3.3 V jumper and ship set to 5 V. At 5 V, communication may be intermittent or absent.

Move the jumper before connecting anything.

Do not identify pins by wire colour. Use the markings on the board and the pinout in the product's manual — colour conventions are not standard and a supplied cable may not follow the one you expect.

Install the driver for the chip, not the product​

This is the part that most often goes wrong, and the rule is short:

The driver belongs to whatever is doing the USB-to-serial conversion.

For a device with its own USB socket, that is the chip inside it:

ChipDriverDevices
CP2102CP210x VCP driver (Silicon Labs)LR900-F, LR900-P, LR868-F, LR24-F, LR24-P
CH340 / CH341CH341SER driver (WCH)LR900-A, MicoAir WiFi Link

For a device on an adapter, it is the adapter's chip — commonly CP2102, CH340/CH341 or FT232. An MTF-01 reached through a CH340 adapter needs the CH340 driver, not anything related to the sensor.

Installing a CP210x driver because the product is "a MicoAir radio" when the adapter in front of it is a CH340 is a well-travelled dead end.

CP2102 Driver Installation (Windows) walks through the CP210x install step by step.

Check the port​

Open Device Manager and look under Ports (COM & LPT):

What you seeWhat it means
a new COM entrygood — carry on
entry with a yellow warning trianglethe driver is missing or wrong. Remove the device and install the right one
nothing newcable, USB socket, power or wiring. Try a different cable first — charge-only cables are common
"Unknown device"work out which conversion chip is involved and install that driver
Finding which COM port is yours

With several serial devices connected, note the list, unplug the one you want, and see which entry disappears. Plug it back in and use the one that returns.

Connect in MicoAssistant​

  1. Open the tool in Chrome or Edge.

  2. If this is a telemetry radio, turn on Radio Config first. It switches the connection to the radio's configuration baud rate for you.

  3. Set the baud rate:

    DeviceBaud
    MTF-01, MTF-01P, MTF-02, MTF-02P and the MT rangefinders115200
    Telemetry radios57600 — set automatically by Radio Config

  4. Click Select Port and pick the device's COM port from the browser's dialogue.

  5. Click Connect.

  6. Wait for the page to identify the device and show its model.

Do not change parameters until the model appears. Until then the tool has a serial port but no confirmed conversation, and the parameter page may not open or may not respond.

Configuring telemetry radios​

The radios are point-to-point pairs, so the rule that governs everything is that both ends must agree.

Read the parameters from the ground end and the air end separately, and make sure the pairing parameters — module address, frequency, rate mode — match. The air end's serial baud rate additionally has to match the flight controller port it is plugged into, which is a different thing and easy to conflate.

The LR24-F-Mini has no USB socket. It is configured over its UART through an adapter, with TX and RX crossed and a common ground.

Full parameter references:

The TRS is different​

The TRS is a combined RC and telemetry system — a transmitter module plus a receiver — rather than a pair of matched radios.

It has three modes: long range, standard and high speed, each with its own telemetry rate, RC refresh rate and serial baud rate. The transmitter module's mode and its baud rate are bound together, and once the receiver is bound it adopts the baud rate for whatever mode the transmitter module is in. So there is normally nothing to configure on the TRS receiver at all.

MSTAR24 is different again​

MSTAR24 is a one-to-many system: one ground unit and several air units. Its firmware, modes and parameters do not map onto the point-to-point radios, and configuring it as though it were an LR900 will not work.

The ground unit presents eight serial ports, ChA to ChH, when connected to a computer, and ChA doubles as the configuration port. Each air unit gets a unique slave number matched to a ground-side channel.

Configuring optical flow and rangefinders​

With the wiring checked and the adapter on 3.3 V:

  1. Connect the sensor and set the baud rate to 115200.
  2. Select Port, choose the adapter's COM port, Connect.
  3. Once the model is shown, open the parameter page — MicoAssistant reads the current values automatically.
  4. Change what you need.
  5. Click save to device.
  6. Confirm it reported success. Power-cycle the sensor and read the parameters back to verify.

You probably do not need to set the protocol any more​

MTF firmware from 1.1.0 onwards has an Auto protocol: the sensor detects which supported flight controller firmware it is connected to and adapts.

With Auto selected, the same sensor works on ArduPilot, PX4 and INAV without being reconfigured — which removes both the configuration step and, more usefully, the need to take a sensor off an aircraft to change firmware.

The MTF-02P additionally has protocol-select solder pads on the board, which override the software setting.

Checking the sensor actually works​

The data page shows live output, which makes it a genuine functional test rather than a configuration screen:

Rangefinder — aim at a flat surface within range and move it closer and further. The distance should follow, smoothly and continuously.

Optical flow — point the lens at a well-lit surface with visible texture and move the sensor sideways at a sensible height. The flow velocity should change with the movement and settle when you stop.

This is worth doing before an aircraft is assembled around the sensor.

Full sensor manuals: MTF-01 · MTF-01P · MTF-02 / MTF-02P · MT-01P, plus the Optical Flow Setup Guide for the flight controller side.

Troubleshooting​

Work in this order. Each step makes the next one testable, and jumping ahead wastes time on symptoms rather than causes:

driver → port → wiring → device identified → parameters and data

No COM port appears​

  • Is the USB cable a data cable? Charge-only cables are extremely common and look identical.
  • Is the device powered? A sensor on an adapter needs its own supply to be correct.
  • Is the driver installed for the conversion chip?
  • Try another cable and another USB socket, and avoid unpowered hubs.

Yellow warning triangle or "Unknown device"​

The driver is missing, wrong or half-installed. Identify the chip, remove the faulty entry in Device Manager, install the correct driver and reconnect. Restart Windows if it persists.

No ports offered in the browser​

  • Use a current Chrome or Edge. Other browsers do not implement Web Serial.
  • Confirm Device Manager shows the port first — if it does not, this is not a browser problem.
  • Private or incognito windows can block serial access.
  • Allow serial access when the browser asks.
  • Unplug, refresh the page, plug back in.

"Port access denied" or "port in use"​

A COM port can only be open in one program at a time. Close Mission Planner, QGroundControl, any serial terminal, and any other copy of the tool. If it still refuses, unplug and reconnect the device, then restart the browser.

The port opens but no device is identified​

Opening the port only means the browser reached the adapter. Nothing has answered yet. Check:

  • baud rate — 115200 for sensors, 57600 for radios
  • Radio Config enabled, if this is a telemetry radio
  • TX and RX crossed, on anything using an adapter
  • grounds joined
  • 3.3 V logic level
  • the device powered, at the right voltage, running working firmware

It connects and then drops repeatedly​

Usually mechanical or power. Check the cable and every connector for looseness, confirm the supply is steady, and connect directly to the computer rather than through a hub.

Parameters will not save, or do not stick​

Confirm the tool reported a successful write. Then power-cycle the device and read the parameters back — that is the only real proof. For radios, check that the paired parameters still match at both ends and that the air end's baud rate matches the flight controller.

The data page shows nothing​

Confirm the device is identified first. Then baud rate, wiring, power and firmware, and reconnect.

Rangefinder reads zero or does not change​

Zero means no valid measurement. Aimed at the sky, the distance is effectively infinite and beyond range, so it reads zero.

Surfaces the sensor cannot measure produce the same result: glass and other transparent materials, mirrors and strong reflectors, matt black surfaces that absorb the beam, and anything at a steep enough angle to bounce the light away. Check the window is clean, then aim at a flat surface within range.

Optical flow data is frozen or nonsense​

Optical flow needs texture and light. A blank wall, a plain floor, a dim room or an obstructed lens all give it nothing to track. Aim it at a surface with visible detail, in good light, at a sensible height, and move it horizontally.

If the values stay at zero, jump wildly, or never change, go back to connection, power and parameters, and power-cycle it.

Written and maintained by the Robofusion engineering team.