In this guide, we’re taking the exact sketches from our Heltec ESP32 LoRa V3 servo project and walking through how they work—no extra code added. You’ll learn how the transmitter reads a rotary encoder, secures and sends that angle over LoRa, and how the receiver decrypts it and drives a micro-servo. All part and code links are below, and if you order through our affiliate links it helps us keep making these tutorials.

1. Transmitter (TX) hardware & setup

On the TX side you need:

• Heltec WiFi LoRa 32 V3 board (in Meshnology N33 case, powered by 3000 mAh pack)

• Rotary encoder wired to GPIO 6 (CLK), GPIO 5 (DT), GPIO 4 (SW)

• OLED display on I²C (SDA= 4, SCL= 15)

The sketch begins by including and initializing everything exactly as in Heltec_ESP32_LoRa_V3_Sevo_TX_AiRotaryEncoder.ino:

cppCopyEdit#include "AiEsp32RotaryEncoder.h"
#include "HT_SSD1306Wire.h"
#include "LoRaWan_APP.h"
#include "mbedtls/aes.h"
// …
static SSD1306Wire display(0x3c, 500000, SDA_OLED, SCL_OLED, GEOMETRY, RST_OLED);
AiEsp32RotaryEncoder rotaryEncoder = AiEsp32RotaryEncoder(
    PIN_A, PIN_B, SW_PIN, ROTARY_ENCODER_VCC_PIN, false, true, true);
const int homePosition = 90;
const int MAX_ANGLE    = 180;
int servoAngel = homePosition;

In setup(), the code:

• Powers on the display, sets font

• Calls rotaryEncoder.begin(), rotaryEncoder.setup(readEncoderISR), rotaryEncoder.setBoundaries(0, MAX_ANGLE, true) and rotaryEncoder.setAcceleration(20)

• Resets encoder to homePosition

• Initializes LoRa via Mcu.begin(HELTEC_BOARD, SLOW_CLK_TPYE) and sets up RadioEvents, channel, and parameters exactly as in the provided sketch.

2. Sending the angle securely

Every loop cycle runs rotary_loop(), which:

• Reads the encoder in the ISR

• When servoAngel changes, packages it into a 16-byte buffer, encrypts with AES-128 (encryptAES() from the sketch), and calls

  cppCopyEditRadio.Send(data, sizeof(data));
  
  
  

• Sets lora_idle = false until OnTxDone() fires and resets it.

3. Receiver (RX) hardware & setup

On the RX side you need:

• Heltec WiFi LoRa 32 V3 board (same case/battery)

• Micro-servo (e.g. SG90) on GPIO 6 (or any tested PWM pin)

• OLED display

The sketch in Heltec_ESP32_LoRa_V3_Sevo_RX.ino starts with:

cppCopyEdit#include <ESP32Servo.h>
#include "HT_SSD1306Wire.h"
#include "LoRaWan_APP.h"
#include "mbedtls/aes.h"
// …
const int servoPin       = 6;
const int SERVO_DUTY_MIN = 400;  // us
const int SERVO_DUTY_MAX = 2400; // us
Servo    myservo;
int      servoAngel     = homePosition;

In setup(), it:

• Powers on Vext for the display/LoRa module (VextON())

• Calls Radio.Init(&RadioEvents) and configures RX with the same LoRa parameters

• Attaches the servo with myservo.attach(servoPin, SERVO_DUTY_MIN, SERVO_DUTY_MAX) and centers it at homePosition.

4. Receiving, decrypting, and driving the servo

The core is the OnRxDone(uint8_t *payload, …) callback:

cppCopyEditdecryptAES((uint8_t*)rxpacket, userKey);
if (isNumber(rxpacket)) {
  servoAngel = atoi(rxpacket);
  myservo.write(servoAngel);
  delay(15);
}
Serial.println("Angle: " + String(servoAngel));
lora_idle = true;

It decrypts the 16-byte block, converts to an integer, and immediately updates the servo.

5. PWM pin support & servo tuning

We tested these ESP32 pins for PWM output and they all work for driving a micro-servo:

CopyEdit1, 2, 3, 4, 5, 6, 19, 35, 36, 38, 39, 40, 41, 42, 45, 47, 48

For a standard SG90, our code uses a pulse range of 400 µs (0°) to 2400 µs (180°), which gives a smooth, full sweep without jitter.

6. Wiring diagram

Below are placeholders where you can drop in your TX and RX schematics:

Code & Affiliate Links

All of the above sketches are available for download in the “Code & Resources” section below. If you’d like to build this yourself, please consider buying your Heltec LoRa32 V3 module, Meshnology N33 case, rotary encoder, and SG90 servo via our affiliate links. It costs you nothing extra and helps us keep making free tutorials like this!

Video Chapters for Reference

• 00:00 Introduction & Overview

• 00:05 Remote Control Concepts

• 00:19 LoRa Communication Basics

• 00:23 Hardware Preview

• 00:28 Case & Battery Showcase

• 01:03 Module Features

• 01:42 Specs & Connectivity

• 02:54 Powering the Servo

• 03:05 Wiring & Pinout

• 09:35 Antenna Placement

• 11:04 Case Assembly

• 29:26 Uploading Sketches

• 35:09 Range Test 1.2 km

• 36:38 Range Test 1.4 km

• 38:41 Performance Recap

• 43:04 Conclusion & Support