How to Upload a .hex File to Arduino on macOS Using AVRdude

If you’re an Arduino enthusiast or developer working on macOS, you might need to upload precompiled .hex files directly to your board which can’t be done through Arduino IDE. Windows users have a GUI based software named Xloader which is easy but for macOS there is no such kind, so we need to do it through Terminal with the help of AVRdude. Whether you’re troubleshooting, optimizing code, or working with custom bootloaders, AVRdude (AVR Downloader/UploaDEr) is the go-to tool for this task.

In this guide, we’ll walk you through uploading .hex files to Arduino on macOS using AVRdude. You’ll learn how to set up AVRdude, identify your Arduino’s serial port, craft the perfect command, and resolve common errors. Let’s dive in!

1. What is AVRdude?

AVRdude is a command-line utility for programming Atmel microcontrollers (like those in Arduino boards). It lets you upload firmware (.hex files), read chip contents, and configure fuses. Unlike the Arduino IDE, AVRdude offers granular control, making it ideal for advanced projects.

2. Installing AVRdude on macOS

Option 1: Use the Arduino IDE’s Built-In AVRdude

The Arduino IDE includes a preconfigured AVRdude. If you have the IDE installed, navigate to:

Option 2: Install via Homebrew

For standalone use, install AVRdude via Homebrew through Terminal:

Press Command+Space and type Terminal and press enter/return key.

In terminal enter:

brew install avrdude

Homebrew Official page: link

Verify Installation:

avrdude -v

3. Locating the AVRdude Configuration File

AVRdude requires a config file (avrdude.conf) to communicate with your board. Arduino IDE users can find it at:

/Applications/Arduino.app/Contents/Java/hardware/tools/avr/etc/avrdude.conf

Homebrew users will find it in /usr/local/etc/avrdude.conf or /opt/homebrew/etc/avrdude.conf.

4. Finding Your Arduino’s Serial Port

1. Unplug your Arduino and run:

   ls /dev/cu.*

2. Plug in the Arduino and run the command again. The new port (e.g., /dev/cu.usbmodem14101) is your Arduino’s serial port.

Note: Older boards may appear as /dev/cu.usbserial-XXXX.

5. Building the AVRdude Command

Here’s the command template (replace placeholders with your details):

/Applications/Arduino.app/Contents/Java/hardware/tools/avr/bin/avrdude \
-C /Applications/Arduino.app/Contents/Java/hardware/tools/avr/etc/avrdude.conf \
-v -p [MCU] -c [PROGRAMMER] -P [PORT] -b [BAUD] -D -U flash:w:[FILE].hex:i

Key Parameters Explained

• -p [MCU]: Microcontroller model (e.g., atmega328p for Uno, atmega2560 for Mega).
• -c [PROGRAMMER]: Use arduino for most boards.
• -P [PORT]: Your Arduino’s serial port (e.g., /dev/cu.usbmodem14101).
• -b [BAUD]: Baud rate (Uno/Nano/Mega: 115200; older boards: 57600).
• -U flash:w:...: Path to your .hex file.

Example for Arduino Uno and NANO

avrdude -C /Applications/Arduino.app/Contents/Java/hardware/tools/avr/etc/avrdude.conf \
-v -p atmega328p -c arduino -P /dev/cu.usbmodem14101 -b 115200 -D -U flash:w:blink.hex:i

6. Fixing Permission Issues

If you get a “Permission Denied” error:

sudo chmod 777 /dev/cu.YOUR_PORT

For a permanent fix, grant your user access via:

1. System Preferences → Security & Privacy → Privacy → Full Disk Access
2. Enable Terminal or your terminal emulator (e.g., iTerm).

7. Troubleshooting Common Errors

Port Not Found

• Ensure the Arduino is connected and recognized in Tools → Port in the Arduino IDE.
• Reboot if the port doesn’t appear.

Device Not Responding

• Verify the MCU model, programmer type, and baud rate.
• Double-check wiring for breadboard-based setups.

“Invalid File Format”

• Confirm your .hex file is valid and compiled for the correct board.

8. Pro Tips for Advanced Users

• Read Fuses/Chip Data:

  avrdude -p [MCU] -c [PROGRAMMER] -P [PORT] -b [BAUD] -nv

• Backup Existing Firmware:

  -U flash:r:backup.hex:i

• Use Makefiles: Automate uploads for frequent projects.

9. FAQs

Q: Can I use AVRdude for non-Arduino AVR boards?
Yes! AVRdude supports most Atmel microcontrollers.

Q: Why is my upload speed slow?
Lower the baud rate (e.g., -b 9600) for unstable connections.

Q: How do I compile a .hex file from an Arduino sketch?
In the Arduino IDE, enable “Export Compiled Binary” under Sketch → Export Compiled Binary.

Conclusion

AVRdude unlocks powerful control over Arduino programming, letting you upload .hex files without the Arduino IDE. By mastering the command-line workflow, you’ll streamline development and tackle advanced projects with confidence.

If you have any issues while uploading please comment below, we will try to help you.