# pn532

> This skill provides expert knowledge for interfacing with the PN532 NFC controller.

- Author: Mike Schneider
- Repository: michschn/claude-plugin-marketplace
- Version: 20260116223758
- Stars: 0
- Forks: 0
- Last Updated: 2026-02-06
- Source: https://github.com/michschn/claude-plugin-marketplace
- Web: https://mule.run/skillshub/@@michschn/claude-plugin-marketplace~pn532:20260116223758

---

# PN532 NFC Controller Skill

This skill provides expert knowledge for interfacing with the PN532 NFC controller.

## Activation Triggers

Activate this skill when the context includes:
- Code with PN532 references (class names, defines, includes)
- NFC/RFID communication code patterns
- Frame construction matching PN532 format (0x00 0x00 0xFF preamble)
- Commands like InListPassiveTarget, InDataExchange, SAMConfiguration
- I2C address 0x24 or 0x48 in NFC context
- ISO14443, MIFARE, FeliCa, NDEF protocol handling

## Keyword Detection
- `pn532`, `PN532`
- `InListPassiveTarget`, `InDataExchange`, `SAMConfiguration`
- `0xD4` (host to PN532 TFI)
- `MIFARE`, `ISO14443`, `FeliCa`, `NFCIP`
- `NFC_`, `nfc_`, `Nfc` combined with read/write/poll/detect

## Knowledge Base

If `knowledge/overview.md` exists, it contains:
- Complete command reference with byte formats
- Register map and configuration options
- Protocol-specific sequences
- Timing specifications
- Error code definitions

Reference this for accurate details. If it doesn't exist but PDFs are in `knowledge/`, suggest `/pn532-init-docs`.

## Proactive Behaviors

### Frame Construction
When seeing manual frame building, verify:
- Preamble: 0x00 0x00 0xFF
- LCS = ~LEN + 1 (two's complement)
- DCS = ~(sum of TFI + DATA) + 1
- Postamble: 0x00

Flag if checksums appear incorrect.

### Command Sequences
Suggest proper sequences:
- Reset → SAMConfiguration before any card operations
- InListPassiveTarget → InDataExchange for card communication
- Authentication before protected MIFARE sectors

### Common Anti-Patterns

| Pattern | Issue | Suggestion |
|---------|-------|------------|
| No ACK check after command | May miss errors | Always verify ACK before reading response |
| Fixed delays instead of IRQ/ready | Inefficient, unreliable | Use interrupt or poll ready signal |
| Ignoring error byte in response | Silent failures | Check byte after response code |
| No timeout on card operations | Can hang forever | Set appropriate RFConfiguration timeouts |
| RF field always on | Wastes power, heats antenna | Disable between operations if battery powered |

### Interface-Specific Guidance

**I2C Mode:**
- Poll ready bit or use IRQ line
- Handle clock stretching
- Use repeated start for read after write

**SPI Mode:**
- Status read before data read
- Watch for busy flag
- Proper SS timing

**HSU Mode:**
- Wake up with extended preamble if sleeping
- Handle baud rate configuration
- Watch for frame sync issues

## Response Style

When activated:
1. Acknowledge the PN532 context
2. Reference documentation when providing specific values
3. Show complete frame examples with all bytes
4. Highlight timing-critical operations
5. Suggest the `/pn532-*` commands for deeper analysis