update:  This is the process i went through to try to get my duet3 6hc to take a firmware update. My initial attempt left me with a board that was stuck with the small red leds dimly light. This means the board is ready to accept firmware but i could not get it to cooperate. I went as far as direct communication with the amtel and still came up empty, so after sleeping on it I tried a fresh start

1. used a small usb cable made for communication

2 downloaded a duet3 version of Bossa   ( https://github.com/Duet3D/BOSSA/releases/tag/1.9.1a-duet3d)

3 downloaded the prevous stable version of duet3 6hc bin

4  placed the reset pin holding the reset button, removing pin then button

5 selected port and file in bossa, wrote the .bin and YES!

How to Recover a Duet 3 6HC Stuck in BOSSA Mode Using a Raspberry Pi

If your Duet 3 6HC is stuck in BOSSA mode and does not recover after flashing the firmware, this guide will help you reflash the bootloader using a Raspberry Pi as an SWD programmer.

🔍 Why is My Duet 3 6HC Stuck in BOSSA Mode?

• If your Duet 3 6HC stays in BOSSA mode after flashing firmware, it means the bootloader is either missing or corrupted.
• You need to reinstall the bootloader using SWD (Serial Wire Debug) before uploading the main firmware.

🛠 Required Tools

✅ Raspberry Pi (any model with GPIO, e.g., Pi 3, Pi 4, Zero, etc.)
✅ Duet 3 6HC Board
✅ Jumper Wires (Female-to-Female)
✅ MicroSD Card (for firmware updates later)
✅ Duet3Bootloader-SAME5x.bin (Download from Duet3D GitHub)

1️⃣ Identify the SWD Header on Duet 3 6HC

To flash the bootloader, you must connect the Raspberry Pi's GPIO pins to the Duet 3 6HC SWD header.

📌 SWD Header Location on Duet 3 6HC:

• The SWD header is a small 5 or 6-pin unpopulated header near the Atmel SAME51 microcontroller.
• It is usually labeled SWD, JTAG, or DEBUG.

2️⃣ Wiring: Connect Raspberry Pi to Duet 3 6HC

🖥 Raspberry Pi GPIO Pins → SWD Pins on Duet 3 6HC

⚠️ Important Notes:

• Only use 3.3V power (Pin 1) if unsure; using 5V may damage the microcontroller.
• Ensure correct wiring to avoid programming errors.

3️⃣ Install OpenOCD on Raspberry Pi

1. Update the Raspberry Pi

   sudo apt update && sudo apt upgrade -y
   

2. Install OpenOCD (SWD Debugging Tool)

   sudo apt install openocd -y
   

3. Check if OpenOCD is installed

   openocd --version
   

   • You should see a version number like OpenOCD 0.10.0 or newer.

4️⃣ Configure OpenOCD for SWD Communication

1. Create an OpenOCD configuration file

   nano duet3.cfg
   

2. Add the following content to the file:

   interface bcm2835gpio
   bcm2835gpio_peripheral_base 0x3F000000
   bcm2835gpio_speed_coeffs 236181 60
   transport select swd
   set WORKAREASIZE 0x4000
   source [find target/atsame5x.cfg]
   bcm2835gpio_swd_nums 25 11
   bcm2835gpio_srst_num 24
   

3. Save and exit (CTRL+X, then Y, then Enter).

5️⃣ Start OpenOCD and Flash Bootloader

1. Start OpenOCD

   sudo openocd -f duet3.cfg
   

   If everything is working, you should see output like:

   target halted
   

2. Open another terminal window and run:

   telnet localhost 4444
   

3. Erase the chip

   reset halt
   at91samd chip-erase
   

4. Flash the Duet 3 6HC Bootloader

   flash write_image erase Duet3Bootloader-SAME5x.bin 0x00000000
   verify_image Duet3Bootloader-SAME5x.bin 0x00000000
   reset run
   

5. Power-cycle the Duet 3 6HC by disconnecting and reconnecting power.

6️⃣ Flash the Main Firmware

Now that the bootloader is installed, you need to upload the main firmware.

1. Download Duet3Firmware_MB6HC.bin from Duet3D GitHub.
2. Flash it using BOSSA:

   bossac --port=usb -e -w -v -b Duet3Firmware_MB6HC.bin -R
   

3. Restart the board and it should now boot normally!

🎯 Expected Outcome

✅ Bootloader installed
✅ Duet 3 6HC no longer stuck in BOSSA mode
✅ Now ready to use RepRap Firmware

If you encounter any issues, double-check:

• Wiring connections
• That OpenOCD is running correctly
• That you are using the correct bootloader file

Need help? Comment below! 🚀