How to connect APM Airspeed Sensor (Pitot Tube) to INAV

Recently released INAV 1.7.2 introduced new hardware support: analog airspeed sensors. I’ve written new but it is new only to INAV. Analog airspeed sensors aka APM Pitot Tubes aka Ardupilot Airspeed Meter and one the market for years. And they are cheap. By cheap, I mean below $30. And until recently they were usable only in APM world.

Pitot Tube for INAV

MPXV7002 differential pressure sensor

APM Pitot Airspeed Sensor for INAV


The hardware we are interested in, are Pitot tubes based on MPXV7002 differential pressure sensor.

Those are 5V devices. All INAV flight controllers are 3.3V devices and that creates a small problem. 3.3V analog to digital converters cannot be used to measure 5V signal.

MPXV7002 Pins

To overcome this problem, a 1:2 voltage divider will be required. You will need two resistors with the same resistance. Anything from 1kOhm to 1MOhm will do. It is really up to you. I used 100kOhm resistors and it worked fine.

APM Pitot voltage divider

INAV already expects 1:2 voltage divider is used, so you do not need to set anything else.

MPXV7002 APM pitot tube voltage divider


Before connecting the airspeed sensor, you also have to find a free ADC converter. Most boards have 3 analog-to-digital converters: Vbat, Current and RSSI.

  • Vbat is not a good choice. Even if it is not used (rare case), it has its own voltage divider that would break measurements
  • Current is our first candidate
  • RSSI is the second one

Since most of my airplanes have current meters, I use a RSSI channel. To prepare APM Airspeed Sensor to use RSSI ADC channel, goto CLI and:

  1. get adc_channel and note channel assigned to RSSI pin. In my case it was channel 3
  2. set rssi_adc_channel=0 – disable RSSI ADC
  3. set airspeed_adc_channel=3 – map ADC channel 3 to airspeed sensor
  4. set pitot_hardware=ADC – enable analog pitot tube
  5. save

Steps 4 and 5 can also be done via Configuration tab in Configurator, but other have to be performed in CLI.


In the latest official release of INAV: 1.7.2 Pitot tube usefulness is somehow limited: airspeed can only be saved in Blackbox logs. Also, a list of boards supporting to function is short: Airbot F4, AirHeroF3, KFC32F3, Omnibus F4 and OpenPilot Revolution.

But, next release (INAV 1.8 or 1.7.3) will:

  1. Enable analog airspeed sensor on more boards
  2. Display current airspeed in OSD (only boards with build in OSD)
  3. Perhaps even closed loop speed control will be added, but this is absolutely not confirmed yet

APM airspeed sensor installed on flying wing

12 thoughts to “How to connect APM Airspeed Sensor (Pitot Tube) to INAV”

  1. Hello Dziku,

    adding indicated airspeed to a board is very useful and makes flying more safe.
    Thank you for the instructions on how to do this with a FC board in INAV.

    I use the omnibus F4 v2.0 (with onboard current sensor) and/or a v3 board with a lemon RX (dsmx) with telemetry and anaolog RSSI output.

    As I want to use all functions (RSSI, Current sensing and Volt indication), I am interested in how to do that.

    You were describing on Youtube, that you “inject the RSSI as one of radio channels”.

    Can you explain in little more detail how to do this, and what I require for this?

    Best regards,


    1. you need one analog channel for this pitot tube to work. period. and i’m affraid my knowledge of lemon rx is non existent to help here

  2. thank you.
    Installed everything and works!
    Just have an issue with a residual airspeed. It shows about 10km/h.
    Sometimes it fluctuates between 3 and 12km/h.

    1. It is fine. Well, maybe not fine, but we have to live with it. Pressure diff for such low speed is so small than pressure sensor noise and ADC resolution is not enough.

  3. Ok, I will see how it copes in flight. Maybe it is accurate enough (I did yet not test-fligh). In your video, it looks fine!
    On my other autopilot systems (FY AP and MyFlyDream) there was an option to set it to “Zero” on ground. The fluctuations thereafter were less than 2 km/h.
    I guess, there is no way in INAV to calibrate/setting to zero?

  4. hi forgive my ignorance, if i understand your post, i need to to connect the signal cable to the rssi port on the board and find a gnd and 5v?, i have a matek f405 wing fc, and it has 5v ports, would i still need to add resistors? dont know if you have a picture with how you wired it up? also thanks for this you seem to be the only person on the web who has got this right.

  5. Hi,
    I’m trying to set-up a Matek F765 on INav for a wing, and have the Matek ASPD-4525 airspeed sensor wired to the FC’s CL2 and DA2 with +5v and ground (This sensor specifies +5v). I powered the board with a 3s battery to ensure the full 5v is applied.
    On the bench, looking at the ‘Sensors’ tab in iNav, the sensor is detected but shows a randomly / quickly varying signal which is offset around 100 cm/s or 1m/s, with values around +/- 30%. I would expect some ‘noise’ around the zero speed value but does this seem reasonable, please? I can’t really test in a laminar flow air stream until I fly it which will be many weeks away!
    I would like some confidence to progress the pitot tube installation, please!

    Many thanks, Andy

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