This tool allows one to show or set the serial number in the Prusa Edition of the 32u2 bootloader. It requires access to a ISP (In System Programming) tool like the AVRISP, USBISP, USBASP or many others. Also, having access to the Go compiler helps :)

I have multiple Prusa and Prusa clone machines, each having their own Einsy logic board. All clone machines unfortuantly have no serial number in their USB descriptors, making it imposible to map the machines consistently to a usb tty device. E.g. 5 machines having /dev/serial/by-id/usb-Prusa_Research__prusa3d.com__Original_Prusa_i3_MK3____________________-if00 does not make finding the right one any easier.

Usage: EinsySerialNumber [-create] [-filename filename] [SerialNumber]

Usage of EinsySerialnumber: -create Create the file if it does not exist (default true) -filename string Name fo the eeprom image we insert the serial number in (default "32u2.eep")

• Clone, download, copy/paste the source files onto your local disk.
• Execute go build . to create the EinsySerialNumber binary.
• (optional) Copy the binary to /usr/local/sbin.

Use avrdude to extract the current content of the 32u2 EEPROM:

sudo avrdude -C /usr/local/etc/avrdude.conf -v -p atmega32u2 -c usbasp -P usb -U eeprom:r:32u2.eep:r

If you get an error message, stop here and figure out what is wrong. If you cannot read the 32u2's EEPROM, there is no use continuing.

Run the EinsySerialnumber tool without arguments, it will list the current serial number. If you are using a China clone or a Einsy board directly from Ultimachine, there is likely no serial number shown.

$ ./EinsySerialnumber 
Serial number: CZPX****X004X******

Now we're ready to setup our own serial number, I prefer to use the machine name, the date I build it and a serial number all seperated by X'es. But it is totally up to you. It is advisable to use 19 characters though.

./EinsySerialnumber NOTOX20180604X00001
Serial number: NOTOX20180604X00001

Now write the modified EEPROM image back to the 32u2:

sudo avrdude -C /usr/local/etc/avrdude.conf -v -p atmega32u2 -c usbasp -P usb -U eeprom:w:32u2.eep:r

For those interested, the serial number seems to be placed in the EEPROM, address 0x100 till 0x100+19, so only 20 valid charcters.

For record keeping, I will also add the binary image (32u2.bin) of the flash to the repository so people can reflash the 32u2 if their version is not identical as to the Prusa one. Use at your own risk as it is a binary image I do not have the source of.

Sadly I cannot find the source of the 32u2 USB>serial converter, as such I can only speculate it has some special commands to read/write the serial number without having to jump to all of the above hoops. Hopefully one day it will be released as opensource as well so we can verify this assumption.