Extracting HEX Code from a Programmed Arduino: A Comprehensive Guide

Whether you need to reinstall the code on a new board or distribute your project without the original sketch, knowing how to extract the HEX code from your programmed Arduino is essential. In this guide, we will explore two methods to obtain the HEX code, one using the Arduino Integrated Development Environment (IDE) and the other using the AVRDUDE command-line tool.

Method 1: Using Arduino IDE

The Arduino IDE is the go-to tool for most users due to its user-friendly interface. Here is a step-by-step guide to extracting the HEX code:

Open Arduino IDE: Launch the Arduino Integrated Development Environment IDE on your computer. Select the Correct Board and Port: Go to the Tools menu, then select the board you are using under the Board section. Also, select the correct port under the Port section. Locate the Sketch: If you have the original sketch code you have uploaded, open it in the IDE. However, this step is not necessary if you already have a HEX file. Compile the Code: Click on the checkmark icon (or Verify) to compile the sketch. This will generate the HEX file. Find the HEX File: After compiling, go to File Preferences in the Arduino IDE. Note the path for the build folder within the Arduino IDE installation directory. The default path is usually something like:

Sketchbook Location/hardware/arduino/avr/bootloaders/...

Method 2: Using AVRDUDE

If you want to extract the HEX file directly from the Arduino without having the original code, you can use AVRDUDE, a command-line program. Here is a step-by-step guide to using AVRDUDE:

Install AVRDUDE: If you haven’t already, install AVRDUDE. It should be pre-installed with the Arduino IDE, but if not, you can install it separately. Connect Your Arduino: Connect your Arduino to your computer via USB. Open Command Line/Terminal: Open a command prompt (Windows) or terminal (macOS/Linux). Run AVRDUDE Command: Use the following command to read the flash memory and save it as a hex file:

avrdude -p atmega328p -c arduino -P COM3 -b 115200 -U flash:r:output.hex:i

Explanation of the command:

-p atmega328p: Specifies the type of microcontroller used in your Arduino. Replace with your specific microcontroller if different.

-c arduino: Specifies the communication method used. This is usually "arduino."

-P COM3: Specifies the COM port to which your Arduino is connected. Replace with your appropriate port, e.g., /dev/ttyUSB0 on Linux or on macOS.

-b 115200: Specifies the baud rate.

-U flash:r:output.hex:i: Creates the output.hex file containing the code from the flash memory of the microcontroller.

Check the Output: After running the command, check the directory where you used the command for the output.hex file.

Note: If you use an Arduino board with a different microcontroller, such as the ATmega2560, be sure to specify the correct part number with the -p option in the AVRDUDE command.

Ensure Permissions: Make sure you have the necessary permissions to access the serial port on your operating system.

By following either of these methods, you should be able to successfully obtain the HEX code from your programmed Arduino. This makes it easier to distribute your projects or back up your code, ensuring that you never lose your hard work.