Update — Sunlu T3 Firmware

To update the firmware on your Sunlu T3 (the "Terminator"), you will typically use the microSD card method. Since the printer's board is a clone of the SKR E3 Mini V2, it is designed to recognize and flash a specific file name upon startup. Firmware Update Steps

Download the Firmware: Get the official firmware file (usually firmware.bin) from the Sunlu Support Page.

Note: Ensure you download the version specifically for the T3 32-bit board. Prepare the microSD Card: Use a card that is 8GB or smaller if possible.

Format it to FAT32 with an allocation unit size of 4096 bytes. Clear all other files from the card. Sunlu T3 Firmware Update

Transfer the File: Copy the firmware.bin file to the root directory of the card.

Crucial: The file must be named exactly firmware.bin. If the printer has been updated before with that name, some users recommend slightly changing the name (e.g., firmware_1.bin) to trigger the flash, but firmware.bin is the standard. Flash the Printer: Turn off the printer. Insert the microSD card into the printer's slot. Turn the printer on.

The screen will remain blank for about 15–30 seconds while it updates. Do not turn off the power during this time. To update the firmware on your Sunlu T3

Verify & Reset: Once the main menu appears, go to Configuration > Advanced Settings and select Store Settings or Load Defaults to ensure the new firmware parameters are active. Important Post-Update Tips

Jam Detection: Many users report that official firmware v3.40 has buggy jam detection. If your printer stops randomly, try turning this off in Configuration > Jam > OFF.

Z-Offset: Updating firmware often resets your Z-offset. You will need to re-level your bed and re-calibrate your Z-offset immediately after the update to avoid nozzle crashes. What’s Good ✅

Custom Firmware: If the official version doesn't meet your needs, there are community-maintained Marlin configurations on GitHub and Printables that enable features like improved 5x5 bed leveling.

Are you updating to fix a specific bug (like the Z-axis being off), or are you looking to enable new features like Klipper or manual mesh leveling?

AI responses may include mistakes. For financial advice, consult a professional. Learn more

What’s Good ✅

  • Fixes thermal runaway bugs – Early T3 units had false thermal runaway triggers; updates resolve this.
  • Improves mesh bed leveling – Some versions better store and recall ABL data.
  • Silences stepper motors – Later firmwares enable better stealthChop settings for quieter operation.
  • Adds features – Like manual filament change, baby-stepping, and power-loss recovery (though the last is controversial).

Primary Sources:

  1. Sunlu Official Website (Support/Download section)
  2. Sunlu GitHub Repository (Look for "Sunlu_T3" or "T3-STM32")
  3. Official Sunlu Facebook Group (Files section – often the most up-to-date source as engineers post beta versions here)

What’s Bad ❌

  • No official GUI updater – You must flash via SD card and rename .bin files manually. No USB/Cura direct update.
  • Screen mismatch risk – The T3 uses a third-party touch screen (DGUS or stock Creality-style). Flashing the wrong screen firmware can brick the display.
  • Lack of clear changelogs – Sunlu rarely posts detailed version history. You rely on community forums.
  • Potential feature loss – Some updates disable power-loss recovery to free memory, or break filament runout sensing.

Step‑by‑Step Firmware Update

10) Rollback / recovery

  • Keep a copy of original firmware and configuration.
  • To revert, flash the original .bin via the same method used for update.
  • If bootloader is corrupted, use ISP programmer or ST‑LINK to restore original bootloader and firmware.