DaVinci Junior cartridge reset (Page 2 of 58)

I have an app called NFC tools with a lock option. I will wait until my second spool is down to only a few meters and try it. If it works it should allow me to print unlimited even with only a few meters left on the spool as long as it can't write to the card and tell it is empty.

So I'm trying to lock the tag but it fails with NFC tools and the app you used crashes when I try to use it. I'm not sure what other app to use now. How did you verify the tag was locked?

I had a second thought today. What if the printer doesn't write anything to the chip at all. Maybe each chip had a unique serial number and the internal memory of the printer just stores which chips have been used and how much filament was used on each chip. Putting the partially used chip back in simply tells the printer which spool it was and it remembers what was left on it....  I started thinking this because all the apps I've used to read the chips just say they are blank.

have to forgive me im only going off conceptual ideas here. But when exactly does the updated data get written to the card?

how does the information exchange between the printer and the NFC chip get authenticated?

The NFC chip itself might be passworded to prevent editing or breaking but is there a way to spoof the authentication to the printer?

you could then have the printer try and write new data to a non existant chip but then spoof the message of " thankyou data recieved" so that the spool itself never becomes updated with new info.. it just constnatly thinks its a full spool?

hi i am up to mine last 30 mtrs off black

when i come to let say 5 mtrs  i am willing to try to lock it

what app should i download on mine samsung S3 ?

The two apps we've been talking about are the only two I've found so far that can Lock a chip are called "NFC tools" and "NFC Tagwriter" the problem is it seems that they fail with some phones.

I tried this again with my wife's phone and the same result happens as my phone. I tried it with an empty chip and one that has 3 meters left, nether worked. But when I put the empty chip in the printer it acts like it doesn't recognize the chip eventhough all of the changes I tried failed. So I don't know if this is because it is empty or because something did change on the chip.

Thank you for that update! Just to clarify which card were you referring to when you said your near-empty card? The yellow one you just locked or a different one? I'm assuming you mean a different card so I wonder why it doesn't recognize it.

I just emptied the another white one that I've been trying to lock to see if it worked and it didn't work for me yet but then again the App keeps crashing before it can lock it. Once I put an "Empty" card back in it says it doesn't recognize the card anymore.

e13, The best way to test at this point would be to check how much filament it thinks is on the spool of yellow you just locked and print something that uses a couple meters. Once it's done printing go back to the info option and see how much filament it says is left. If it's the same number as before it looks like it worked but if it is a lower number then it didn't work. This should be something you could test in a few hours or less with a small to medium print.

If the spool info is stored inside the printer then we should be able to exchange the chips Correct ??

Also i wasnt able to lock mine chip

Sounds like the next step would for someone to send another member a card that is empty and a card with 5 meters or less left on it and let them put it in their printer to see what happens.

It's starting to sound like it's going to take someone writing new firmware for this to work without the nfc chip needed. Unless someone can pull the password from the unit itself.

:T I'm sure that the printer is checking to make sure there is a valid card in the spool and what record to write to. That's probably why you got the spool error. Otherwise we'd be able to start the print with the card, then pull it out mid print and be able to print forever with the same card.

I was able to lock my card and I can confirm that the spool length does still tick down as I run each print. I think we should try exchanging dead cards and see if they work.

I have a feeling since the printer doesn't even recognize the chip anymore once it's empty that it writes something to the card to "Kill" it. So if were going to exchange cards I think an empty card and one with a couple meters left need to be exchanged so that it doesn't have a chance to "kill" the card. BUT since you locked the card e13, maybe if the printer writes something to the card once it reaches zero to "Kill" it, your locked card might not be able to be written to keeping it working... Just maybe

Just joined to follow up on this one. I just took my depleted filament, read it through my RFID RC522 reader for Arduino, and the output was

Card UID: 04 5F B9 2A 97 3C 80
PICC type: MIFARE Ultralight or Ultralight C
Page  0  1  2  3
  0   04 5F B9 6A
  1   2A 97 3C 80
  2   01 48 00 00
  3   E1 10 12 00
  4   01 03 A0 0C
  5   34 03 00 FE
  6   00 00 00 00
  7   00 00 00 00

(and then an error, since its crypted/protected).

I don't know how encrypted rfids work, but unless they send out separate signals depending on the input they get, it would be entirely possible to just fake the singal of a new filament, basically all the time, with a little arduino. All it takes is the RFID dump of a clean chip - and discarding all write attempts. Theres an off-chance the printer checks if the changes written, have been implemented, in which case, the new values from the da vinci jr. needs to be accepted - if possible.

Edit (1)
My chip was on a filament with color natural, 600g - came with the printer. The numbers printed on the spool itself is; printed on a label RFPLCFGBP3ZTH53S0044 - and handwritten on a label 50740120202.

Edit (2)
As I understand it these chips can actually lock out any continuous attempt at password guessing. In the hope that it does not, I have (or I think I have, if my code is correct) at the moment tried the first 16.581.375 combinations (0xff 0xff 0xff 0x0 0x0 0x0 0x0 0x0 0x0) by shear brute force - no luck. Problem is of course, that brute forcing took ~8 hours on the Atmega328 - it has to be repeated 4.228.250.625 times - which is longer than I will (probably) live. I might attempt another 16 mil combinations, with just random number-generating instead.

One way of guesstimating the passphrase, would be, maybe, to sniff the traffic coming from the Da Vinci Jr printer itself. Alas, I do not know how to do this at the moment.

Edit (3)
My guess is that the Da Vinci firmware has some kind of master password, which is seeded with the ID of each unique RFID. In other words, even if I get the key from mine, it will probably not work for anyone else.

Also, theres the off chance, that the firmware stores RFID-tags and their "last known size and usage" to prevent spool-meters to go up again - which in turn, would mean the passphrase either needs to be found, or the memory containing the RFID-tags, erased for each machine.