Antenna rotator controller with azimuth and elevation

Today we’re sharing a project that’s especially interesting for any ham who wants to take a serious step up in antenna control: a rotator controller with azimuth and elevation, compatible with most common amateur radio software.

It’s an ideal solution for automatic satellite tracking, letting the antenna follow the pass precisely and with no manual intervention. No aiming by eye, no reliance on closed proprietary controllers: this is a reproducible, modern system meant to actually be used.

Work by Juan Manuel, EA7KWF

This work comes from Juan Manuel (EA7KWF), whom I met in the Riojanos por la Radio community. He’s one of those people it’s easy to talk shop with: he shares, he explains, and he doesn’t keep anything up his sleeve.

One of his latest projects is exactly this rotator controller, and he has generously offered to bring it to Acuántico Power as a step-by-step guide, so that anyone can replicate it at home.

Exactly what you’ll build

The end result of this project is a WiFi rotator controller capable of moving:

Azimuth (up to 450°)
Elevation (up to 180°)

All of it through GS-232A commands, the protocol understood by most control and satellite-tracking programs used in amateur radio.

The system is based on an ESP32, which acts as the brain of the setup: it receives commands over the network and translates them into real movement using stepper motors.

What the system does

As the code is implemented:

The ESP32 connects to your WiFi network
It uses a static IP
It opens a TCP server on port 4533
It interprets standard GS-232A commands
Controla dos motores paso a paso:
- One for azimuth
- The other for elevation

What you’ll need

Main components

Before you start, it helps to have everything on the table.

1 × ESP32 Dev Module
2 × stepper motor drivers (DRV8825 Kit)
2 × stepper motors (recommended: NEMA 17)
1 × power supply for the motors (12V 4A)
Connection wires
1 × USB cable to program the ESP32

Wiring the components

The code explicitly defines which pins are used, but in practice you don’t need to wire pin by pin.
Using an ESP32 board together with a CNC Shield, the setup is designed to fit directly, with no way to get the orientation wrong.

The CNC Shield has only one possible position on top of the base board, so you just place it correctly and press until it’s properly seated.

Once it’s in place, all you have to do manually is wire the shield’s power the same way as in the following image:

Fitting the motor drivers

This project only uses two axes:

X axis → azimuth
Y axis → elevation

So:

You need to fit two stepper motor drivers in the X and Y positions of the CNC Shield.
The usual kit includes 4 drivers, so you’ll have 2 left over.
You can also buy the CNC Shield and just two drivers separately.

It’s important to respect the driver’s orientation when inserting it into the board, aligning the pins correctly. Never force it in.

Setting the driver voltage (VREF)

Before connecting the motors, it’s essential to set the reference voltage (VREF) of each driver.
This setting limits the maximum current the motor will receive and prevents overheating or damage.

The adjustment is done with the potentiometer built into each driver.

How to calculate VREF

The rule used in this project is simple:

VREF = motor’s maximum current / 2

In this case, 1.7 A motors are used, so the reference value will be roughly:

VREF ≈ 0.8 V

How to measure it

Use a multimeter
Put the negative probe on GND
Measure the voltage at the driver’s potentiometer
Adjust by gently turning the screw until you get the value you want

Juan Manuel explains this process very clearly in PART 4 of the videos, which you’ll find further down in this article.

Setting up the programming environment

Installing the Arduino environment

The whole project is compiled from the official Arduino environment, available for Windows, Linux and macOS.

Adding ESP32 support

To work with ESP32 boards you need to install support from the manufacturer, Espressif Systems.

In the Arduino IDE:

Open Preferences
Add this URL under “Additional boards manager URLs”:

https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
Install the ESP32 package from the boards manager

Installing the required library

Motor control is handled by the AccelStepper library, which you install directly from the IDE’s library manager.

Firmware

Download it here

WiFi configuration

Before uploading the program, you only need to change these values in the code from the editor:

const char* ssid = “YOUR_WIFI_NAME”;
const char* password = “YOUR_WIFI_PASSWORD”;

And check that the static IP you want to assign is free and matches your local network’s ranges:

IPAddress local_IP(192,168,0,50); The IP your ESP32 will have.
IPAddress gateway(192,168,0,1); Your router’s IP.
IPAddress subnet(255,255,255,0); The same.

If your network doesn’t use the 192.168.0.x range, adjust these values before continuing, for example to 192.168.1.x.

Uploading the program to the ESP32

Connect the ESP32 to the computer via USB
En el IDE selecciona:
- Board: ESP32 Dev Module
- Port: the one that appears when you connect the board
Click Upload

If the process finishes without errors, the controller is now programmed.

Software needed to run the controller

For the rotator controller to work properly from the computer, the electronics alone aren’t enough.
You need two pieces of software that act as a bridge between the amateur radio program and the WiFi controller.

Hamlib

The project uses Hamlib, a library widely used in amateur radio to control equipment such as:

Antenna rotators
Transceivers
Satellite tracking systems

Many amateur radio programs don’t talk directly to the hardware; they do it through Hamlib.
In this case, Hamlib takes care of translating the software’s commands (for example, move the antenna to a specific position) into the format the GS-232A controller understands.

In the article about my tool Hamlib Launcher there’s a complete installation tutorial for Hamlib.

HW-VSP3 (Virtual Serial Port)

Besides Hamlib, you need to install HW‑VSP3

This program creates a virtual serial port in the operating system.

What’s it for?

Many amateur radio programs expect to communicate with a rotator through a COM port
Our controller works over the network (TCP/IP)
HW-VSP3 actúa como traductor entre ambos mundos:
- The software thinks it’s talking to a serial port
- In reality, the data is sent over the network to the ESP32

Thanks to this, the controller is compatible with software originally designed for classic RS-232 rotators.

First check

Open the IDE’s Serial Monitor and set the speed to 115200 baud.
When you restart the board you should see:

WiFi connection messages
The assigned IP
The active TCP server

That means the system is ready to receive commands.

Testing GS-232A control

From any compatible software or via a Telnet connection:

IP: the ESP32’s
Port: 4533

Basic commands:

C → returns the current position
W180 045 → moves to azimuth 180°, elevation 45°
S → stops the movement

If the motors respond correctly, the controller is working.

Video documentation

Besides this step-by-step guide, Juan Manuel (EA7KWF) has published a series of videos on his YouTube channel documenting the whole process in detail.

This video material is especially useful for:

Seeing the project working for real
Getting a better grasp of the physical assembly
Clearing up specific questions while flashing the firmware or wiring the motors

If at some point in the build you’re left with a question, these videos will help you tie up loose ends without improvising.

LOW-COST ANTENNA ROTATOR FOR SATELLITE TRACKING – PART 1 – General overview of the project and a working demo

LOW-COST ANTENNA ROTATOR FOR SATELLITE TRACKING – PART 2 – Detailed explanation of the motor controller module

LOW-COST ANTENNA ROTATOR FOR SATELLITE TRACKING – PART 3 – How to flash the firmware onto the controller

LOW-COST ANTENNA ROTATOR FOR SATELLITE TRACKING – PART 4 – Wiring the stepper motors

Some videos used an Arduino that would later be replaced by an ESP32. In practice, that detail doesn’t matter here.
You can also visit the author’s GitHub.

The project continues

This controller isn’t an end point, but a starting point.

Juan Manuel, the project’s author, is already working on the mechanical side: a reduction system, antenna mounts and everything needed to have a complete antenna rotator, designed specifically for satellite tracking.

The idea is to close the loop:
electronics, control, mechanics and real use at the station, with no improvised solutions or external dependencies.

From Acuántico Power we’ll be sharing the upcoming updates as the project moves forward.

If this kind of development interests you, stay tuned.
The best of this rotator is still to come.

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