Again not sure if Dymo firmware deals with that situation, but the above can probably be done on a 30ct PIC. Perhaps sniffing for the first 24-bits of the code on the bus, and then corrupting the last few bits (just pull on SDA for a few cycles), is enough to make the RD operation invalid and have it not decrement. Still wondering if it's necessary to make a complete NFC clone. edit: Oh I see the counter decrements on RD commands, instead. If not, that should create a permanent fix, without the need of repeatedly "refreshing" the NFC tag, or diving into custom I2C slaves that emulate a dummy NFC reader. Not sure if they are smart enough to check if the sent password will unlock the tag (or that the write was successful). If the password is changed, then the Dymo printer won't unlock the tag and can't decrement the remaining labels counter. ![]() Just write the original memory contents to that tag. I wonder what happens if you can get a new tag (or change the existing tag), and use a different password on it. then the password should be somewhere in the I2C serial stream when a label gets printed. If the I2C is unprotected yet the tag is password protected. so probably requires a lot of investment to get a small result on the software part. It's quite an extensive standard, and also not really a mainstream industry to work on the tag side of things. For UHF RFID tags most commonly EPCgen2 is used. I'm not sure what the NXP NFC tags use, or if it's proprietary. The protocol is probably the tougher issue. These RFID tags only contain a few dozen bytes, maybe 256 for large tags, so it doesn't take long to read them. The bitrate at which this happens is only in the order of kbps. The label>reader communicates by shorting it's antenna or coil connection, which the reader can sense and demodulate the transmitted data. The tag harvests energy from this carrier signal to power up, so 100% won't be used for passive tags. The reader>label comunnicates by sending a carrier signal with ASK modulation (the NXP chips says a depth of 20-30%, or optionally 100%). These tags communicate with backscatter (far-field, UHF) or load modulation (inductive, 13.56MHz). all you need is a diode receiver and an antenna switch. I've been researching custom (UHF) RFID tags. How do I print NetStamps with Endicia Online? Printing NetStamps with Endicia Online is very easy.Not all that hard. Can I print shipping labels with my free NetStamps-only plan? To print postage other than stamps you will need to upgrade to a paid Endicia account.ħ. Where do I buy NetStamps Rolls and Label Sheets? Endicia Original NetStamps are available in the Endicia Store:Ħ.
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