Anycubic i3 Mega Marlin Firmware with TFT support

This is my slightly customized version of the Marlin Firmware, gratefully based on derhopp's repo with his remarkable efforts to get the Anycubic i3 Mega TFT screen to work.

I am running this version on an i3 Mega Ultrabase V3 (for distinction of the different versions, check this Thingiverse thread) with FYSETC TMC2208 V1.2 installed. Basically, this should work on every Ultrabase version that has no bed leveling sensor and two Z-axis endstops.

Why use this?

While the i3 Mega is a great printer for it's price and produces fantastic results in stock, there are some issues that are easily addressed:

• Very loud stock stepper motor drivers, easily replaced by Watterott or FYSETC TMC2208. To do that, you'd usually have to flip the connectors on the board, this is not necessary using this firmware.
• Many people have issues getting the Ultrabase leveled perfectly, using Manual Mesh Bed Leveling the printer generates a mesh of the planeness of the bed and compensates for it on the Z-axis for perfect prints without having to level with the screws.
• Much more efficient bed heating by using PID control. This uses less power and holds the temperature at a steady level. Highly recommended for printing ABS.
• Fairly loud fans, while almost every one of them is easily replaced, the stock FW only gives out 9V instead of 12V on the parts cooling fan so some fans like Noctua don't run like they should. This is fixed in this firmware.
• Thermal runaway protection: Reducing fire risk by detecting a faulty or misaligned thermistor.
• Easily start an auto PID tune or mesh bed leveling via the special menu (insert SD card, select special menu and press the round arrow)

How to flash this?

Compile it yourself:

• Download Arduino IDE
• Clone or download this repo
• In the IDE, under Tools -> Board select Genuino Mega 2560 and ATmega2560
• Open Marlin.ino in the Marlin directory of this repo
• Customize if needed and under Sketch, select Export compiled binary
• Look for the .hex file in your temporary directory, e.g. .../AppData/Local/Temp/arduino_build_xxx/ (only the Marlin.ino.hex, not the Marlin.ino.with_bootloader.hex!)

Or download precompiled hex:

• Choose the correct hex file:
• For TMC2208 with connectors in original orientation, use Marlin-AI3M-XXXXXX.hex
• For TMC2208 with flipped connectors, use Marlin-AI3M-XXXXXX-flipped.hex
• If you use the original stepper motor drivers (Pololu A4988 afaik), and didn't do anything to your connectors, you can try to use Marlin-AI3M-XXXXXX-flipped.hex. Can't promise it will work though.

After obtaining the hex file:

• Flash the hex with Cura, OctoPrint or similar
• Connect to the printer and send the following commands:
• M502 - load hard coded default values
• M500 - save them to EEPROM

PID tuning

• Send M303 E0 S200 C8 U1 to start extruder PID auto tuning
• Check the output, after finishing it should report Kp, Ki and Kdvalues
• Send M301 Pxx.xx Ixx.xx Dxx.xx, replacing the xx.xx with the values from the output in the order from above
• Send M303 E-1 S60 C8 to start heatbed PID auto tuning
• Same as above, read the values and send them with M304 Pxxx.xx Ixx.xx Dxxx.xx
• Save with M500

Manual Mesh Bed Leveling

• Level your preheated bed as well as you can
• Send G29 S1, your nozzle will go to the first calibration position
• Don't adjust the bed itself, only use software from here on:
• Use the onscreen controls or a tool like OctoPrint to lower or raise your nozzle
• If 0.1mm steps are not enough, you can send specific commands down to 0.02mm via those three commands:
• To raise: G91, G1 Z+0.02, G90
• To lower: G91, G1 Z-0.02, G90
• When done, send G29 S2 and repeat the process for the next command. Continue with G29 S2every time.
• After finishing the 25 points, the printer will beep and calculate. After seeing ok on the console, enter M500 to save the mesh to EEPROM
• To ensure your mesh gets used on every print from now on, go into your slicer settings and look for the start GCode
• Look for the Z-homing (either just G28 or G28 Z0) command and insert these two right underneath it:
• G501and M420 S1.
• Enjoy never having to worry about an uneven bed again!

Changes:

• Thermal runaway protection enabled
• TMC2208 configured in standalone mode
• Stepper orientation flipped (you don't have to flip the connectors on the board anymore)
• Some redundant code removed to save memory
• Manual mesh bed leveling enabled (check this link to learn more about it)
• Heatbed PID mode enabled
• Buffer & baudrate tweaks to improve print quality over USB
• 12V capability on FAN0 (parts cooling fan) enabled
• No startup beep

Additional features by derhopp:

• Subdirectory support: Press the round arrow after selecting a directory
• Special menu in the SD file menu: Press the round arrow after selecting Special menu

Todo:

• Tweak TMC2208 steps

About Marlin

Marlin is an optimized firmware for RepRap 3D printers based on the Arduino platform. First created in 2011 for RepRap and Ultimaker printers, today Marlin drives a majority of the world's most popular 3D printers. Marlin delivers outstanding print quality with unprecedented control over the process.

Contributing to Marlin

If you have coding or writing skills you're encouraged to contribute to Marlin. You may also contribute suggestions, feature requests, and bug reports through the Marlin Issue Queue.

Before contributing, please read our Contributing Guidelines and Code of Conduct.

Marlin Resources

• Marlin Home Page - The latest Marlin documentation.
• Marlin Releases - All Marlin releases with release notes.
• RepRap.org Wiki Page - An overview of Marlin and its role in RepRap.
• Marlin Firmware Forum - Get help with configuration and troubleshooting.
• Marlin Firmware Facebook group - Help from the community. (Maintained by @thinkyhead.)
• @MarlinFirmware on Twitter - Follow for news, release alerts, and tips. (Maintained by @thinkyhead.)

Credits

Marlin's administrators are:

• Scott Lahteine [@thinkyhead]
• Roxanne Neufeld [@Roxy-3D]
• Bob Kuhn [@Bob-the-Kuhn]
• Erik van der Zalm [@ErikZalm]

Notable contributors include:

• Alexey Shvetsov [@alexxy]
• Andreas Hardtung [@AnHardt]
• Ben Lye [@benlye]
• Bernhard Kubicek [@bkubicek]
• Bob Cousins [@bobc]
• Petr Zahradnik [@clexpert]
• Jochen Groppe [@CONSULitAS]
• David Braam [@daid]
• Eduardo José Tagle [@ejtagle]
• Ernesto Martinez [@emartinez167]
• Edward Patel [@epatel]
• F. Malpartida [@fmalpartida]
• João Brazio [@jbrazio]
• Kai [@Kaibob2]
• Luc Van Daele [@LVD-AC]
• Alberto Cotronei [@MagoKimbra]
• Marcio Teixeira [@marcio-ao]
• Chris Palmer [@nophead]
• Chris Pepper [@p3p]
• Steeve Spaggi [@studiodyne]
• Thomas Moore [@tcm0116]
• Teemu Mäntykallio [@teemuatlut]
• Nico Tonnhofer [@Wurstnase]
• [@android444]
• [@bgort]
• [@GMagician]
• [@Grogyan]
• [@maverikou]
• [@oysteinkrog]
• [@paclema]
• [@paulusjacobus]
• [@psavva]
• [@Tannoo]
• [@TheSFReader]
• ...and many others

License

Marlin is published under the GPLv3 license because we believe in open development. The GPL comes with both rights and obligations. Whether you use Marlin firmware as the driver for your open or closed-source product, you must keep Marlin open, and you must provide your compatible Marlin source code to end users upon request. The most straightforward way to comply with the Marlin license is to make a fork of Marlin on Github, perform your modifications, and direct users to your modified fork.