INAV Airspeed Sensor – which one to choose

INAV flight controllers gives you the option to install airspeed sensor on your airplane, just like in Pixhawk and Ardupilot. And just like in case of Pixhawk and Ardupilot, you have several options in terms of the hardware. Airspeed sensors, also known as Pitot tubes, come in two variants: digital and analog.

Matek Airspeed Sensor ASPD-7002

Digital Airspeed Sensors

Devices based on MS4525 digital differential pressure sensor. They are connected via I2C bus using SDA and SCL pins. They are more expensive than analog sensors, but also give slightly better accuracy. Example Digital Airspeed Sensor

Analog Airspeed Sensors

Just like digital, are also based on differential pressure sensors, but they output measured pressure difference as analog value. Based on MPXV7002 chip. They have to be connected to a free Analog input on a flight controller. On top of that, all 7002 sensors output value between 0 and 5V, while flight controllers can read only between 0 and 3.3V.
This is why, if airspeed sensor, or a flight controller, does not have to built-in voltage divider, you have to build your own one.

There are exemptions from this rule tho. Matek Airspeed Sensor has a divider ready on 1/2 pin. Latest Matek WING flight controllers like F722-WING or F-765 WING have special pins called Air that can accept 5V voltages. Always check hardware specification! Analog Airspeed Sensor for INAV, APM, Pixhawk

More about airspeed sensors and INAV:

Radio modules FS1000A and XY-MK-5V – pros and cons

When looking for radio modules for your next Arduino project, you might have come across the couple named: FS1000A and XY-MK-5V. At first glance, they might look like the next best thing, but it’s not that simple.

FS1000A and XY-MK-5V

Before you start hacking anything with FS1000A and XY-MK-5V, read the following pros and cons:

Pros:

  • simple – to send a signal you do not need much. Only to power them up and set LOW or HIGH on the data pin
  • cheap – true, they are not expensive

Cons:

  • pretty much everything else, including the same things that are their pros…
  • too simple – they are just too simple and offer no other functions than transmitting a wave through the void. No CRC, no packets, so SPI or serial, no bidirectional communication
    everything has to be done in the software, including encoding and CRC.
  • transmitting and receiving devices have to use the same libraries and support on some platforms like Raspberry Pi might be problematic at best
  • the frequency can not be changed!
  • no frequency hopping or spread spectrum
  • you have to get your own antennas
  • range is poor at best and depends on things like voltage of the transmitter
  • build quality varies a lot and you can not be sure that TX and RX are really tuned to the same frequency

Verdict? At leat be very careful when choosing hardware for your next Arduino RF project…

How to connect GPS to ESP32

Thanks to a very versatile Input/Output matrix, it is quite simple to connect NMEA GPS modules to ESP32 MCUs. Not only ESP32 boards have 3 serial ports you can choose from, they can be assigned to almost any pin you want.

In this example we will connect a popular Ublox NEO-M8N like Beitian BN-880 or BN-220 to a ESP32 development board and output current position on a USB serial port using Arduino IDE and TinyGPS++ library. Let's begin

Sketch header and setup routine

Let's include all of our libraries: TinyGPS++ and HardwareSerial

#include "types.h"
#include <TinyGPS++.h>
#include <HardwareSerial.h>

Then, let's assign variables and create TinyGPSPlus and HardwareSerial object called SerialGPS on serial port 1.

TinyGPSPlus gps;
HardwareSerial SerialGPS(1);

No, set's set up everything in a setup function. GPS will be connected with 9600bps and to pins:

  • Serial 1 RX – pin 16 – connect GPS TX pin to it
  • Serial 1 TX – pin 17 – connect GPS RX pin to it
void setup() {

    Serial.begin(115200); //Serial port of USB
    SerialGPS.begin(9600, SERIAL_8N1, 16, 17);
}

When everything is configured, we can listen to data on SerialGPS and send it to TinyGPS++ and decoded data to USB serial port

void loop() {
    while (SerialGPS.available() > 0) {
        gps.encode(SerialGPS.read());
    }

    Serial.print("LAT=");  Serial.println(gps.location.lat(), 6);
    Serial.print("LONG="); Serial.println(gps.location.lng(), 6);
    Serial.print("ALT=");  Serial.println(gps.altitude.meters());
}

Full example is available here. It does other functions too!

How to choose drone motors

One of the mistakes beginner (but not only) pilots and drone builders make is that they use too small motors. People think that if a motor works fine with 5-inch props, it will work with 7-inch props as well. It's not true. In this longish video, I will tell you how to choose motors for your drone: 5-inch, 6-inch, and 7-inch. We will talk about torque, power, a moment of inertia, what happens when you put a too big propeller on a motor.

How to make tape hinges for foam RC airplanes

If you are into making your own RC airplanes (foam, Depron or even balsa and structure) or even repair ready made models, you have to know how to make hinges. Like always, the simplest way is the best, and for small and even medium sized RC airplanes the metod to make hinges (for ailerons, flaps, elevator, etc.) is to use 2 pieces of self-adhesive tape! Here is tutorial on how to do it:

Matek 1G3 VTX and VRX – Long Range 1.2GHz FPV video link that fits your goggles!

There a few things that I can be sure of in life. One of them is that every time I receive a DHL package from Matek, there is something very interesting inside!

Matek 1G3 VTX and VRX 1.2GHz FPV video link

This time, for example, is a pre-production sample of a new FPV transmitter and receiver. This time it’s not 5.8GHz but 1.2GHz. Long Range FPV, here I come!

Matek 1G3 VTX and VRX 1.2GHz FPV video link

Probably the best feature of Matek 1G3 receiver is that it is Fat Shark receiver module compatible! You can just plug it into your FPV goggles or a ground station receiver like Furious FPV Dock-King!

It comes with Matek made 1.2GHz PCB antennas as well!

Matek 1G3 1.2GHz FPV receiver

Matek VTX-1G3 and Matek VRX-1G3 are available on Banggood.