6 - TUTORIAL - Take a brushless motor for a spin with a radio receiver

Video: https://youtu.be/jO2igKp9qUk

Full code and manual on GitHub
Quadcopter frame PCB on OSHW lab

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Table of Contents:

A) Introduction - bypass the flight controller

Welcome to the sixth video in this series, where you are finally going to fire up the first motor of your quadcopter.

In this session, you won’t need to program anything because we are going to bypass the flight controller

and directly connect the receiver to the electronic speed controller (ESC).

This way, you will be able to control the motor directly from a receiver channel, and also test various important active components: the radio system, battery, motor, and ESC.

B) How to connect the Powertrain with the Radio controller

B.1) Let’s Start with the Motor

We will use a small, brushless GEPRC motor rated at 5000 kilovolts.

This motor weighs about 6 grams

and comes with screws to fasten both the motor to the frame and the propeller to the motor.

With a two-cell battery and a 3-inch propeller, this motor can produce around 150 grams of thrust, meaning that four motors will easily lift your quadcopter.

Slide the 3-inch Gemfan propeller down the motor shaft and push it firmly onto the top of the motor.

Use two of the longest screws to fasten it.

Next, cut off the white connector from the three black motor cables, as you will not use it.

Carefully strip each cable so that you can solder them to the frame lead.

The wires are very small, so this step may take a few tries to get right.

Attach the motor to the quadcopter frame using the four shortest screws.

Note: Be sure that none of the screws touch the motor windings to avoid damaging the motor.

B.2) Connecting the Motor to the Battery via the ESC

Next, secure the quadcopter frame firmly to your desk using tape.

We will connect the Motor via the ESC to the Battery Connector,

To connect the motor to the battery through the ESC, you can use wire terminal strips for temporary connections,

but it’s easier to use wire connectors, such as the Wago 221.

First, connect the three motor wires to the black, red, and blue ESC wires.

The order doesn’t matter—if the motor spins in the wrong direction, switching two wires will reverse it. You can fix this later.

Use some tape to secure the wire connectors so they don’t come into contact with the propeller.

Now, connect the XT60 battery connector to the black and red wires from the ESC. In this case, make sure to respect the color coding to avoid any issues.

B.3) Binding the Receiver and Transmitter

Next, connect the ESC to the receiver.

You will need to bind the receiver to the transmitter to enable communication between the two.
For this project, we’re using the FSI6 receiver and transmitter.

Connect the ESC to channel 3 of the receiver,

which corresponds to the left stick on the radio transmitter.

Turn on the power button on your radio transmitter while simultaneously holding the bind key button. The text “RX Binding” should be displayed on the transmitter.

Connect the bind block to the B/VCC pins on the receiver.

Make sure the left stick is in its lowest position to avoid a sudden motor start.

Connect the battery to the XT60 connector to power both the motor and receiver.

You will hear one beep from the radio transmitter, indicating it has coupled with the receiver. The next three beeps will come from the ESC, indicating that the motor is ready to start.

Gradually increase the left stick to start the motor. You are now controlling the motor speed from channel 3 of the transmitter.

B.4) ESC Calibration

One final thing remains: you need to tell the ESC what the upper and lower positions of the transmitter stick correspond to, which is a form of calibration.

Here’s how to proceed:

1. Ensure the battery is unplugged.
   

2. Turn on the radio transmitter and move the throttle stick to its highest position.
   

3. Connect the battery to ensure the ESC enters programming mode. After connecting the battery, you will hear one beep from the transmitter, followed by a series of beeps from the ESC.
   

4. Move the throttle stick to its lowest position between the first and fourth beep. After 2 seconds, the ESC should emit two sets of two beeps, indicating that the calibration is complete.
   

Increase the throttle stick to start and control the motors. If you get a linear response from the lowest to the highest stick position, the calibration was successful.

You should repeat the calibration process for your other three ESCs to ensure a smooth flight later on.

In the next video, you will learn how to connect your receiver to your Teensy and read the signals from your radio transmitter.

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Z) 🗃️ Glossary