{
  "url": "https://proudtek.com/guides/ntag21x-family-memory-map-commands/",
  "sourceUrl": "https://proudtek.com/guides/ntag21x-family-memory-map-commands/",
  "title": "NTAG21x Family — Memory Map and Commands",
  "description": "NXP's NTAG21x family (NTAG213, NTAG215, NTAG216) is the most deployed NFC Type-2 chip family on the planet. The workhorse silicon behind billions of...",
  "kind": "article",
  "imageUrl": "https://proudtek.com/landing-images/ntag21x-family-memory-map-commands-hero.jpg",
  "imageAlt": "Close-up of a 13.56 MHz NFC/RFID transponder inlay with copper antenna coil — NTAG21x-class Type-2 chip hardware",
  "imageGallery": [
    {
      "url": "https://proudtek.com/landing-images/ntag21x-family-memory-map-commands-hero.jpg",
      "alt": "Close-up of a 13.56 MHz NFC/RFID transponder inlay with copper antenna coil — NTAG21x-class Type-2 chip hardware"
    }
  ],
  "breadcrumbs": [
    {
      "name": "Home",
      "url": "https://proudtek.com/"
    },
    {
      "name": "Guides",
      "url": "https://proudtek.com/guides/"
    },
    {
      "name": "NTAG21x Family — Memory Map and Commands",
      "url": "https://proudtek.com/guides/ntag21x-family-memory-map-commands/"
    }
  ],
  "summary": [
    "NXP's NTAG21x family (NTAG213, NTAG215, NTAG216) is the most deployed NFC Type-2 chip family on the planet."
  ],
  "faq": [
    {
      "question": "Which NTAG21x chip should I specify for a Google review or loyalty card?",
      "answer": "NTAG213. 144 bytes of NDEF user memory comfortably holds a review URL with UTM parameters (e.g. https://g.page/r/abc?utm_source=table_talker) plus a counter-mirror placeholder, and NTAG213 is the least-expensive chip in the family by a meaningful margin at volume. Only step up to NTAG215 when the payload exceeds ~130 bytes net of TLV overhead. Typical signs: multi-line vCards, long URLs with tracking parameters, embedded text records."
    },
    {
      "question": "Can a single reader firmware handle all three NTAG21x chips without modification?",
      "answer": "Yes, if the firmware reads GET_VERSION first. Byte 6 of the GET_VERSION response disambiguates the chip (0x0F = 213, 0x11 = 215, 0x13 = 216). Everything else (command set, page size, encoding) is identical. Firmware that hard-codes the upper-bound page address (39 / 129 / 225) will fail on a different chip; firmware that derives it from GET_VERSION works across all three."
    },
    {
      "question": "Is NTAG213 sufficient for anti-counterfeit applications?",
      "answer": "Only for low-risk categories. NTAG213 offers the ECDSA originality signature (verifies the chip itself is genuine NXP silicon) plus ASCII mirror of UID and counter. Together these give you 'tap-count anomaly detection'. If the same URL is scanned with mismatched counters, something is off. But NTAG21x has no dynamic cryptographic signature over the URL itself, so a counterfeiter who photographs a legitimate scan and replays the URL in a sticker on a counterfeit item will fool any naive verification. High-risk categories (luxury, pharmaceuticals) require NTAG424 DNA with SUN + CMAC."
    },
    {
      "question": "What is the difference between static lock bytes and dynamic lock bytes?",
      "answer": "Static lock bytes at page 2 protect pages 3–15 (the bottom of the tag including the CC and the first 13 pages of user NDEF). Dynamic lock bytes, at page 40 on NTAG213, page 130 on NTAG215 and page 226 on NTAG216, protect everything above page 15. Both are one-way. Once a lock bit is set it cannot be cleared. Production workflow typically writes the NDEF, verifies, then sets dynamic lock bytes to seal it permanently."
    },
    {
      "question": "How do I prove a tag is genuine NTAG21x and not a counterfeit 'NTAG-compatible' chip?",
      "answer": "Three steps. (1) Send GET_VERSION: byte 1 must be 0x04 (NXP vendor ID), byte 2 must be 0x04 (NTAG product type), and byte 6 must match the expected variant (0x0F / 0x11 / 0x13 for 213/215/216). (2) Send READ_SIG: receive 32 bytes. (3) ECDSA-P224 verify those 32 bytes against NXP's published public key (AN11350) over the tag's UID. Chinese-OEM 'compatible' chips typically pass step 1 but fail step 2 or return a signature that fails verification."
    },
    {
      "question": "What is AUTH0 and how do I configure password-protected memory?",
      "answer": "AUTH0 is the page address from which password authentication is required. If AUTH0 = 0x04, every page from 4 upwards is protected. Any READ or WRITE without a prior successful PWD_AUTH returns NAK. Configure by: (1) writing your 32-bit PWD and 16-bit PACK to the PWD and PACK pages, (2) setting CFG1.ACCESS bits to enable protection (protect writes only, or reads and writes), (3) writing the starting page number to CFG0.AUTH0. Then your reader prefaces every protected transaction with PWD_AUTH 0x1B PPPPPPPP and expects the PACK back."
    },
    {
      "question": "Why does my NFC counter start at 000001 instead of 000000 after personalization?",
      "answer": "Because the NFC counter is incremented *before* the mirror value is computed, on every successful READ or FAST_READ once CFG1.ACCESS.NFC_CNT_EN is set. Your personalization workstation's own reads increment the counter. Workaround: enable the counter only as the final step of personalization, *after* the NDEF is written and verified, to avoid the personalization reads being counted. Or simply accept that the first in-field read shows counter = 000001 + however-many-personalization-reads."
    }
  ],
  "procurementFields": [],
  "collectionGuidanceFields": [],
  "coreGuidanceFields": [],
  "articleGuidanceFields": [
    {
      "label": "Best for",
      "value": "NTAG21x Family — Memory Map and Commands supports RFID and NFC evaluation, comparison, and sourcing decisions."
    },
    {
      "label": "Compare first",
      "value": "Compare NTAG21x Family — Memory Map and Commands against reader compatibility, chip family, material, and deployment environment."
    },
    {
      "label": "What to confirm",
      "value": "Confirm target application, compatibility requirements, customization needs, quantity, and sample expectations before quoting NTAG21x Family — Memory Map and Commands."
    }
  ],
  "sourceLinks": [],
  "related": [],
  "productSpecs": [],
  "machineJsonUrl": "https://proudtek.com/machine/guides/ntag21x-family-memory-map-commands.json",
  "machineTextUrl": "https://proudtek.com/machine/guides/ntag21x-family-memory-map-commands.txt",
  "author": {
    "name": "Proud Tek Editorial Team",
    "title": "RFID & NFC Technical Content Team",
    "expertise": [
      "RFID manufacturing",
      "NFC technology",
      "Access control systems",
      "Smart card engineering"
    ]
  },
  "publisher": "Proud Tek Co., Limited",
  "datePublished": "2026-04-18",
  "dateModified": "2026-06-10T18:00:00Z",
  "lastReviewedDate": "2026-06-10T18:00:00Z",
  "credentials": [
    "ISO 9001:2015",
    "ISO 14001:2015",
    "RoHS Compliant",
    "CE Marking",
    "REACH Compliant"
  ],
  "generatedAt": "2026-03-16T01:42:30.697Z"
}