mcu 'mcu': Unable to connect

[john858257]

Hello

Im excited to start using the features of OpenNeptune and I followed all installation
steps however I cant seem to get the firmware to flash and I get the following error in Fluidd:

mcu 'mcu': Unable to connect

The installation ran smoothly up until I put the MicroSD Card with the 2 x .bin files into the printer and powered up but the they do not get renamed to .CUR

I am running a Neptune 4. Any advice would be much appreciated as I've been trying to resolve this all day. I've tried replacing the EMMC as well.

John

[halfmanbear]

That is unusual (as it's not connecting at all). The microSD formatted in FAT32?

I'm sure you've followed these instructions just leaving then here for reference. https://github.com/OpenNeptune3D/OpenNept4une/wiki#flashing--updating-klipper-mcus

[john858257]

Hi,

Yes followed all the steps to a tee with no issues or errors until the .bin files step where it doesn't seem to pick up the files on the MicroSD at all. I also tried going back to Elegoo version and it just displays the Machine info page and doesn't pick up the firmware / fix pack either.

I'm thinking I have a main board issue, I'm discussing with Elegoo support too.

[john858257]

Their support is proving to be a bit slow and naturally I'm impatient/getting 3D printing withdrawels, so I'm wondering if I should try the below in order to find out why the MCU is not working:

https://r6e.dev/neptune_4/guides/mcu.html

What do you guys think? Do you think I would have any luck installing the OpenNeptune firmware through this route?

[halfmanbear]

Our method for manually flashing/ recovering MCU firmware is below;

Remove machines bottom panel.

On the main board locate the pads labeled BOOT0. "They should be behind the micro SD card slot, on the other side of the RESET button."

Power on the machine

Whilst pressing down on the RESET button. Bridge the BOOT0 pads.

"Using a metal implement of appropriate shape and size (such as tweezers), bridge the gap between the two pads. BE VERY CAREFUL TO NOT TOUCH ANY OTHER COMPONENTS!"

Release RESET button first then un-bridge the BOOT0 pads.

Leave the printer on and SSH in (as mks) and type:

sudo service klipper stop

wget https://github.com/OpenNeptune3D/OpenNept4une/raw/refs/heads/main/mcu-firmware/12-093-full.bin

stm32flash -w 12-093-full.bin
 -v /dev/ttyS0

If this last command fails retry the BOOT0 & RESET button combination above. Then re-run the command;

stm32flash -w 12-093-full.bin
 -v /dev/ttyS0

Once successfully flashed;

sudo reboot 

(then power cycle after a few minutes)

[john858257]

Thank you for the above. I have just tried a couple of times but I get

http://stm32flash.sourceforge.net/

Using Parser : Raw BINARY
Size : 262144
Interface serial_posix: 57600 8E1
Failed to init device, timeout.

Im gonna presume the MCU has failed and its not even connecting to the main board. I guess I'll have to wait for an Elegoo Support rescue.

[halfmanbear]

This error is typical when trying this method, if you are certain you are pressing the relevent button & bridging the pads in the correct sequence/ method then this should work after a couple of tries.

Note: I've updated the instructions in the previous comment to be more clear.

[bkane4]

I was able to run stm32flash but still getting this error.

[halfmanbear]

That could be a klipper problem Klipper3d/klipper@7f822f3

[john858257]

Thanks for the follow up comments

I think my issue was a fried MCU chip or similar because I’ve now changed the motherboard (elegoo supplied a new one) and now working again.

Thanks for the support