Hello.

I've built a 3D printer with the following configuration:

Motherboard: SKR Mini E3 V3 (https://github.com/bigtreetech/BIGTREETECH-SKR-mini-E3)
LCD screen: MKS Mini 12864 V3 (https://github.com/makerbase-mks/MKS-MINI12864-V3)
Firmware: Marlin 2.1.1

I want to print from the LCD SD card reader, so in Marlin I use:

#define SDCARD_CONNECTION LCD

Everything works fine, but I'm facing a problem to update the firmware.
Until now, I've always flashed the firmware by copying the firmware.bin file to the SD card and inserting it in the onboard SD reader. This works as expected.
The LCD SD card reader also works fine and I can print from it.

My problem is that, with the printer assembled, the physical access to the onboard SD card reader is not possible. This way, I can't flash the firmware over it anymore.
I tried doing it over the LCD SD card reader, but if I insert the SD card with the firmware.bin file, the printer ignores it, like if the SD card were empty. Restarting the printer doesn't solve this.
Is it possible to flash the firmware over the LCD SD card reader? Or it must be done over the onboard SD card reader?

Another solution that would work for me is to have an SD card always connected to the onboard SD card reader and copy the firmware.bin file to it over USB.
I tried to do that using Repetier, but I'm able to copy the files only to the LCD SD card reader.
Is it possible to update the firmware on the onboard SD card over USB while bieng able to print from the LCD SD card?

Thanks.

You MUST use the onboard sdcard to update the firmware
The firmware is updated with the bootloader code. this only knows about the onboard sdcard. There is no source for this, and no way to change it. You would also need a stlink device to change the boot loader on the controller.

Edited 2 time(s). Last edit at 09/06/2022 10:24PM by Dust.

you would need to build with build environment STM32G0B1RE_btt_xfer so you can copy the firmware.bin to the sdcard
The first flash with this needs to be done traditional way with sdcard, subsequent flashing can be done over USB.

you would also need to enable MULTI_VOLUME to support the two sdcards and modify the upload script to tell it to select the onboard sdcard slot

This is a very experimental system, which may or may not work on the SKR Mini E3 V3

Edited 1 time(s). Last edit at 09/06/2022 10:34PM by Dust.

Thanks for the hints.
I will give it a try.