LP5562 requires 2.7V min but NFC energy harvesting produces only 1.8V.
New architecture: SAMD21 drives 6 red LEDs directly via TCC0/TCC1
hardware PWM through current-limiting resistors.
Key changes:
- Add TCC PWM driver (src/led/pwm.rs) for 6 GPIO-direct LED channels
- Rewrite pattern engine: software waveform LUTs (sine/triangle/square/
heartbeat) replace LP5562 hardware execution engines
- Add XBLK v2 EEPROM format with 16-byte pattern entries + playlist
- Add TC4 50Hz ISR for animation, power governor for current budget
- Add NTAG5 EH provisioning: persistent config + session trigger
- Critical finding: SRAM passthrough in persistent EEPROM blocks all
NFC access when MCU unpowered — CONFIG_1 must be session-only
- Add provision_eh.py PCSC tool for ACR1552 reader
- Update CLAUDE.md and STATUS.md for new architecture
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
XBLK binary format for pattern library in NTAG5 upper 1K EEPROM:
- 16-byte header (magic, version, pattern count, active index, CRC-16)
- Up to 9 × 112-byte fixed-size pattern entries
- Deserializer + serializer in src/pattern/mod.rs
- MCU self-provisions hardcoded patterns on first boot (no XBLK found)
- Subsequent boots load active pattern directly from EEPROM
- Python serializer tool for future PCSC-based pattern uploads
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
