cd ~/Documents/Arduino/libraries git clone https://github.com/dhiltonp/hexbright.git

Quick Fix: The URL is Dead (Repo Deleted ~2020)

The 404 error means the GitHub repo dhiltonp/arduino-boards no longer exists (deleted or archived years ago). No worries—we'll use the manual method that's rock-solid for HexBright (it's just an ATmega328P like the Uno, so no fancy package needed). This skips Boards Manager entirely and gets you connected in <1 minute.

Step 1: Remove the Bad URL

1. File → Preferences
2. Delete https://raw.githubusercontent.com/dhiltonp/arduino-boards/master/package_hexbright_index.json from Additional Boards Manager URLs.
3. Click OK.
4. Tools → Board → Boards Manager → search "hexbright" → if it shows, click Uninstall (cleans up any partial install).

Step 2: Manual Board Definition (Copy-Paste Only)

This adds HexBright as a custom board using a simple boards.txt file. Works on any Arduino IDE version (1.x or 2.x).

1. Find/create the hardware folder (exact path):

   ~/Documents/Arduino/hardware/          (macOS/Linux)
   C:\\Users\\<yourname>\\Documents\\Arduino\\hardware\\   (Windows)
   
   

   • If Arduino folder doesn't exist, create it.
   • Inside hardware, create hexbright folder (so path is .../hardware/hexbright/).

2. Create boards.txt inside the hexbright folder:

   • Open a text editor (TextEdit, Notepad, etc.).

   • Copy-paste exactly this content:

     #####################################################
     hexbright.name=HexBright
     
     hexbright.upload.protocol=arduino
     hexbright.upload.maximum_size=30720
     hexbright.upload.speed=57600
     hexbright.upload.tool=avrdude
     hexbright.upload.verbose=true
     
     hexbright.bootloader.low_fuses=0xff
     hexbright.bootloader.high_fuses=0xde
     hexbright.bootloader.extended_fuses=0x05
     hexbright.bootloader.path=optiboot
     hexbright.bootloader.file=optiboot_atmega328.hex
     hexbright.bootloader.unlock_bits=0x3F
     hexbright.bootloader.lock_bits=0x0F
     
     hexbright.build.mcu=atmega328p
     hexbright.build.f_cpu=16000000L
     hexbright.build.core=arduino
     hexbright.build.vid=0x2341
     hexbright.build.pid=0x8036
     hexbright.build.usb_product="HexBright Flex"
     hexbright.build.usb_manufacturer="HexBright"
     hexbright.build.board=AVR_HEXBRIGHT
     hexbright.build.verbose=true
     
     

   • Save as boards.txt (plain text, no .rtf or .doc).

3. Restart Arduino IDE.

4. Select the board:

   Tools → Board → HexBright (it appears at the bottom under "Custom Boards").

Step 3: Fix the Port (The Real Issue)

Your error shows /dev/cu.usbserial-0001, but HexBright uses a CDC-ACM port (like /dev/cu.usbmodem...).

1. Unplug everything USB except the HexBright. Re-plug it.