ESP32 Mini Quadcopter Development Guide

Preface#

Do you remember looking up at the blue sky as a kid—watching airplanes draw white lines across it—and imagining the broad, open view an Air Force pilot sees when looking down at the earth? That kind of scene always sparked a desire to fly. Unfortunately, I never had the body to become a pilot, which is a bit of a regret. Luckily, with today’s technology and the boom of open-source hardware, I don’t have to be an aerospace engineer to build my own aircraft by hand—and to catch a glimpse of the scenes I once dreamed about.

This post will walk you through the process of building a small ESP32 quadcopter UAV. It won’t be a perfect product like a DJI drone. But every line of code and every solder joint here is a step toward the sky. Even if the most you’ve done before is light up an LED, as long as you follow this tutorial, you’ll be able to make these PCBs and motors fly.

I don’t want this to be a dry technical manual. I’d rather it be a flight diary that accompanies you as you explore the unknown. Ready? Let’s go for it!

Software Installation#

Before we can really fly, we need to set up the build environment first. Here we choose Espressif’s official ESP-IDF. The learning curve is a bit steeper, but it lets us control the hardware more deeply and makes it easier to diagnose issues later.

1. Download the installer

2. Environment setup wizard

3. Wait for installation and fix drivers

Create a Project#

Now that the environment is ready, we should run something. In the embedded world, blinking an LED is a ritual, and printing “Hello World” is faith. Let’s have the ESP32 say hello to the world first.

1. Launch and initialize

2. Build and flash

Hardware Walkthrough#

Now that the software environment is set up, let’s look at the hardware side. I won’t go into great detail about SMD soldering here; just prepare the parts according to the BOM and PCB files in my open-source repository ↗. Below are some small but important pieces of knowledge you’ll still need once everything is ready.

Hardware design plan#

• Power: first use the ps7516 chip to boost battery voltage (3.7V-4.2V) up to 5V, then use AMS1117-3.3 to step it down to 3.3V. This mainly provides buffering.

• Motors: use 8520 coreless motors. The shaft diameter is either 1.0 mm or 1.2 mm, and it must match the inner diameter of the propeller, otherwise it won’t fit. Even if you force it on, the propeller will be off-center.

• Battery: use a 1S LiPo (length < 65, width < 17.5, thickness < 7.5). Common voltages are 3.7V and 3.8V. Choose 3.7V; both can work, but 3.8V is more likely to puff. Choose a PH2.0 connector for easier plugging/unplugging.

• LED indicators

  • Blue: aircraft status indicator, used to show which part of the internal flight-control loop is currently running, e.g. initializing or initialized but not armed.
  • Battery indicator (Yellow): shows whether battery voltage is sufficient.
  • Connection indicator (Green): shows the connection status between the flight controller and the ground station / remote controller.
  • Power indicator (Red): lights up when powered on to indicate power is OK.

Enter download mode#

Our little aircraft uses the ESP32-S3-WROOM-1 (D2N8) module. It’s not just a Wi-Fi chip—its dual-core 240MHz compute power is enough to handle attitude estimation and PID control at the same time. For triggering the chip’s flashing mode, the circuit is set up like this. The download circuit is manual: press the boot and rst buttons on the flight controller to enter download mode (hold boot, then press rst once to enter download mode). Then you can flash via UART directly (buy a USB-to-UART adapter and connect the four pins rx, tx, 3.3V, gnd).

Hardware assembly and wiring#

Motor ports: the four motor ports M1, M2, M3, M4 correspond to the four propellers.

Prop installation and motor wiring: be sure to install clockwise/counter-clockwise props correctly! Usually diagonal motors rotate in the same direction (e.g., M1/M3 clockwise, M2/M4 counter-clockwise), and props must match (A props for clockwise motors, B props for counter-clockwise motors). If you install them wrong, the aircraft will spin in place or crash immediately. Also, we use red/blue wire motors because many black-wire motors sold today rotate opposite to the program’s definition. If you want to use black/white wire motors, you need to manually swap the wire order.

Software Architecture#

1. Attitude estimation (AHRS)

2. PID control

3. Motor mixing

motor1 = throttle + pitch_out + roll_out - yaw_out;
motor2 = throttle + pitch_out - roll_out + yaw_out;
motor3 = throttle - pitch_out - roll_out - yaw_out;
motor4 = throttle - pitch_out + roll_out + yaw_out;

Ground Station Debugging#

During flight, it’s hard to judge whether PID parameters are good or bad with the naked eye. That’s when a ground control station (GCS) helps. I recommend AnoTC (Anonymous Ground Station).

1. Connect: connect the ESP32 via USB or Wi-Fi telemetry.
2. Waveform observation: in the GCS, you can view real-time attitude curves.
3. Online parameter tuning: no need to re-flash every time you change parameters. Via the protocol, you can modify PID parameters in real time and see the effect immediately.

Conclusion#

From a single build-and-flash command to the moment the aircraft trembles into the air for the first time, you may go through countless crashes, broken props, and compile errors. But when the algorithm you wrote by hand makes the aircraft hover steadily in the air, the sense of achievement is unmatched.

This post mainly helps you sort out the overall workflow of ESP32 UAV development. Later I’ll add more practical photos and detailed wiring diagrams in the corresponding places.