NFC tags

NFC commands share schemas, permissions and the native executor across HTTP, WebSocket, MCP, HTML and Lua. Open and unlock Dikciz, enable NFC in Android settings, then present a tag. An absent adapter, disabled radio, foreground restriction or deadline is an explicit failure. Each request owns reader mode and closes its tag connection afterward.

Read and select a tag

nfcRead / dikciz_nfc_read waits up to timeoutMilliseconds, default 30000 and range 1 through 120000. It returns tagIdBase64, Android technology names, NDEF support and available NDEF bytes. A tag without NDEF support still returns its identity and technologies.

Every tag operation accepts expectedTagIdBase64 from a prior read. Other presented tags are ignored until the deadline. The ID is at most 64 decoded bytes. A tag ID is a selector, not proof of identity or authorization.

Write NDEF

nfcWrite / dikciz_nfc_write requires dataBase64 containing a complete Android-compatible NDEF message, at most 32768 decoded bytes. Malformed messages fail before reader activation. Read-only tags and insufficient capacity fail explicitly. format: true permits formatting an unformatted compatible tag; its default is false.

Successful writes report state: written and verified. An ordinary NDEF write attempts read-back comparison. Formatting reports verified: false. A lost tag, failure or timeout can leave partial effects. Inspect the tag before retrying a write.

Raw transaction

nfcTransceive / dikciz_nfc_transceive requires technology and dataBase64. Supported technologies are IsoDep, NfcA, NfcB, NfcF, NfcV, MifareClassic and MifareUltralight, subject to the presented tag and phone. Android's per-technology maximum also applies.

ioTimeoutMilliseconds defaults to 5000, range 1 through 60000, for technologies with configurable I/O timeouts. The outer deadline still applies. Responses include Base64 bytes and their count, bounded to 32768 bytes. Raw commands may modify a tag. Use the tag manufacturer's protocol and do not treat successful transport as application-level success.

Payment cards and multi-command protocols

A payment card can advertise IsoDep and NfcA without supporting NDEF. ndefSupported: false means there is no NDEF message through this API; it does not mean the phone cannot communicate with the card. The returned tag ID is not an account number.

Contactless payment terminals implement EMV application selection and APDU exchanges over ISO-DEP. Dikciz exposes raw nfcTransceive transport, not an EMV decoder, wallet provisioning or a payment terminal. JavaScript or Lua can encode commands and decode responses through that transport, subject to the card's own access rules.

Each nfcTransceive request opens one tag connection, sends one command and closes it. There is no persistent session or multi-command batch. Card application selection or authentication state may be lost between requests, so a stateful EMV conversation is not guaranteed by chaining independent calls. A higher-level protocol needing a continuous connection requires additional native session support. No secret card keys, PIN or payment authority are implied by a successful raw exchange.

References: Android IsoDep, EMV contactless.

Example

{"type":"nfcRead","timeoutMilliseconds":30000}

No tag is emulated by this API. RF transactions need a compatible physical tag. See hardware inventories and command schemas.

Companion workflows

See the focused companion guide for the new shared commands, native screens, required access and actual outcome states.