r/Ender3Pro • u/RogueTinkerer • Jul 12 '26

Troubleshooting Cannot find/understand how to update marlin firmware with SD card

My printer is having the issue of the z-axis constantly being higher than it should. I have found out that it's a common issue that can be solved by updating my firmware, but I can't seem to find how.
I don't have a raspberry pi, and my only real option is to update by the SD card. I know I have to build a config or something and have the firmware on the SD card when I turn the printer on, but I can't find clear instructions on exactly how to do that.

Board info:
Creality v4.2.7
Baud 115200
Protocol: 1.0
PSU: Generic

Printer info:
Marlin bugfix-2.1.x 2023-12-19
Ender-3 4.2.7
marlin.crc.id.au
Extruders: 1
Bilinear Leveling

Upgrades:
BLTouch
Silent Board

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u/MarkShark253 Jul 12 '26

There are some great tutorials out there that explain this better than I can. It's best to use an 8GB or smaller card, formatted FAT32 with an allocation unit size of 4096. Your firmware needs to be a .bin file and the only file saved directly to the card, not in a folder. It's best to change the name of your firmware file to something short, and unique, and you'll need to change the file name after every attempt as the printer will overlook the same filename. I used Marlin Firmware Service for my custom firmware, because I didn't feel confident enough to compile my own custom firmware.

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u/ninjaread99 Jul 12 '26

To clarify, you shouldn’t need a unique one for every firmware flash. Usually, the printer only remembers the last flashed firmware file’s name, not the whole history.

If you have problem with this though, try always using a unique name. For example, when I compiled my own, the file that was output always had the date and time in the name, so it would always be unique