Dymo 550 Thermal Printer DRM Hacking

[Fara]

Have you got the pass through to work? I have a few dmo label rolls that I can use for the rfid if I can just find a way for pass through to work

My bluepill works only in a pass-through mode and I have the same rev I board.

To your previous question, as I understand, the EEPROM has a counter and it backs up the counter on the RFID chip. So you need to have both the pass-through mode and the writing protection enabled on EEPROM. Funny, it would stick to the number at which you put the WP mode. Better making it on a full roll. Mine now stuck at 20 labels left.

Regarding to the issue that you have, it is hard to debug by just looking at the printer's LED.
The counter is more or less independent from the chip validation. So if you don't have chip confirmed, you would not get to the counter.
I would suggest to return the status of the bluepill to the UART and maybe even dump the data from I2C to UART.

[AKRUA]

Would compiling my own binary possibly be beneficial to me rather than using a precompiled binary? Or would that not effect how the pass through works?

[Fara]

Would compiling my own binary possibly be beneficial to me rather than using a precompiled binary? Or would that not effect how the pass through works?

The pass-through mode turns on when a real tag is presented to the RFID reader. You don't need to recompile the code for that.

You would need to recompile only if you want to change the code (e.g. adding the UART logging).
There are different binaries available for different simulated tags. I don't remember what happens when you have a conflicting roll type in the binary and in your real tag. So make sure, the roll type/size is correct.

Also, make sure your real tag is close enough to the RFID reader. It should be within ~20 mm.

Also, I think the easiest part to screw up is the wiring. Make sure you have the right resistors and wiring.

Ah, another thing I noticed. The printer is blinking if anything is wrong. Including other cables. Make sure you have connected all the cables. Make sure the paper also has holes similar to the original and the paper is pushed forward.

[AKRUA]

I should mention, i am looking at the print queue in windows to see what the error state is, which is where im getting the "unknown label type" message

[sp7dpt]

@js_12345678_55AA Hi, I have a printer with a Rev. E board.
I programmed the Bluepill new release (v1.1.1):

freedmo-default-sku-S0722530: the label is detected
freedmo-default-sku-S0722560: the label is detected
freedmo-default-sku-S0722540: the label is not detected, but the LED in the printer does not blink. It shows a blank label with no counter. After manually selecting the label, printing is possible.
Other random labels are also not detected automatically.
Is there anything I can do about this?

[Axis-3790]

Is this thread dead now? I was really hoping we could get a resolution on the REV I board. I have 2 of them and I know others are have them as well. I am not sure of the process to looking into this but I am resourceful if anyone has any leads. I would love to contribute. I am just not sure where to start.

[Bastelwastl]

Hello everyone,

with the newer board revisions with large EEPROM, I discovered that every new label SKU that isn't yet stored in the EEPROM must be saved to the EEPROM once. Otherwise, the DMO will flash, and you'll get an error message in the program.
This means you have to disable the read-only-mode (remove the solder blob on the EEPROM, it's better here to solder in a switch , two wires that can be twisted together or similar).
Insert the unknown original label you want to learn to the DMO or the unknown SKU from the bluepill, turn on the DMO (DMO shouldn't blink with read-only disabled), print a test label, turn off the DMO, and switch back to read-only mode (solder blob or similar). This has to be done with every unknown SKU.

For those who new install the bluepill to their DMO, install first the bluepill with the choosen SKU, print one or two bluepill-emulated-labels, if this works then
enable/ switch on read-only-mode on the EEPROM, one step before the other results in a non working flashing DMO (if the label SKU is not in the EEPROM).