Arduino Nano ESP32 Communication Templates

This repository contains simple, functional C++ templates for common communication protocols used in embedded systems. The code is written for the Arduino Nano ESP32 (ESP32-S3) and focuses on clarity, structure, and reusability.

Each protocol is implemented in its own file with clear comments and minimal abstraction - meant to serve as a foundation for real applications and as a reference for how these interfaces work at a low level.

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Overview

This project provides clean, working examples for:

• UART (Serial1) – basic RX/TX echo and line-based reading
• I2C (Wire) – bus scanning and simple register read/write helpers
• SPI (SPIClass) – master mode transfers with chip-select control
• RS-485 (UART half-duplex) – DE/RE control for direction-safe communication

The intent is to keep these examples short and easy to follow, while still covering the essential setup and handling for each interface.

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Project Structure

NanoESP32_Comms/
├── NanoESP32_Comms.ino // Main entry point – select which demo to run
├── UartComm.h / .cpp // UART communication template
├── I2CComm.h / .cpp // I2C communication template
├── SPIComm.h / .cpp // SPI communication template
├── RS485Comm.h / .cpp // RS-485 communication template
└── utils.h // Small helper functions (trim, hex dump)

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Getting Started

1. Clone or copy the project

Place this folder in your Arduino sketch directory (typically ~/Documents/Arduino/).

2. Open the sketch

Open NanoESP32_Comms.ino in the Arduino IDE.

3. Select the board

• Board: Arduino Nano ESP32 (ESP32-S3)
• Port: whichever port the board enumerates as

4. Choose a demo

In NanoESP32_Comms.ino, set exactly one of the demo flags to 1:

#define RUN_UART_DEMO 1
#define RUN_I2C_DEMO 0
#define RUN_SPI_DEMO 0
#define RUN_RS485_DEMO 0

5. Configure pins

Edit the pin definitions at the top of the .ino file to match your hardware wiring:

static constexpr int PIN_UART_RX = 5;
static constexpr int PIN_UART_TX = 4;

6. Upload and test

Upload the code and open the Serial Monitor at 115200 baud to see logs.

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Demos

UART

A basic Serial1 echo. Anything typed in the Serial Monitor is sent to Serial1, and received lines are printed back to the terminal.

I2C

Scans the bus for connected devices and reads a sample register (WHOAMI at 0x75 on address 0x68) if present. Useful for quickly verifying connections.

SPI

Performs a simple register read/write using SPI master mode with configurable chip select. Designed to be adapted for common SPI sensors and devices.

RS-485

Implements half-duplex communication using UART with a DE/RE pin. Sends periodic packets and echoes any received messages. Useful for Modbus RTU or general serial bus applications.

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Customization

• Adjust pin assignments and communication speeds as needed.
• Use these templates as a starting point for your own sensor or peripheral drivers.
• The code is portable across ESP32 boards with minimal pin remapping.

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Dependencies

All dependencies come from the Arduino Core for ESP32:

• Arduino.h
• Wire.h
• SPI.h

No external libraries are required.