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>
M3: 5 autonomous LP5562 engine patterns (breathe, heartbeat, slow_pulse,
rgb_cycle, color_wash) with dual LED mode support (RGBW/Mono3) and
2mA/ch current for EH-realistic power budget.
M4: NTAG5Link I2C slave driver with session register reads, EEPROM
write-verify, and NDEF Type 5 text record output. Config check validates
CONFIG_0, CONFIG_1, EH_CONFIG against expected values and writes result
as NFC-readable text. Verified on hardware: config check passes, NDEF
readable via ISO15693 from phone.
Key findings from hardware testing:
- SRAM passthrough arbiter blocks NFC reads while I2C bus is active
(resolves naturally when MCU enters STANDBY — noted in M7 plan)
- NTAG5 must be in I2C slave mode (not master) for MCU communication
- EH config mask set to 0x00 (skip check during external power testing)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add src/pattern/ module with 3 engine patterns:
- Breathe: smooth ramp up/down (~2.5s cycle, 1 engine)
- Heartbeat: double-pulse with long rest (~1.6s cycle, 1 engine)
- RGB cycle: phase-offset breathing via trigger sync (3 engines)
Patterns support both RGBW and 3-channel monochrome LED modes via
LED_MAP configuration. Main loop cycles through all 3 patterns (8s
each) while LP5562 runs them autonomously — MCU just idles.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add error-resilient firmware with diagnostic LED blink patterns
(3 slow = alive, solid = I2C OK, fast burst = I2C error). Document
EVM external MCU wiring: disconnect P6 EN jumper, power VDD from
XIAO 5V, leave SCL/SDA jumpers in place with MSP430 unpowered.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Reverse-engineered the MSP430 serial protocol on the LP5562EVM:
- I<addr><reg> reads, O<addr><reg><data> writes, status 00=OK / 02=NAK
- EN pin must be jumpered to VDD (MSP430 doesn't drive it after reset)
- CONFIG (0x0B) is write-only, W_CURRENT (0x09) not writable via bridge
- LED cycling verified: all 4 channels respond to direct PWM control
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Hall sensor + LP5562 EN wired-AND circuit design (DRV5032FB/FE,
1M pull-up, open-drain topology) with three interaction modes:
boot-time recovery, tap-to-swap, hold-to-confirm recovery
- NTAG5 config check tool (tools/ntag5_config_check.py) using
uFCoder library for ISO15693 transparent mode via uFR Zero reader.
Supports inventory + addressed mode for multi-tag fields.
- Updated DEVELOPMENT_PLAN with I2C bus management notes for
LP5562 (0x30) + NTAG5Link (0x54) shared bus
- Updated README with wired-AND hardware diagram, hall sensor
interaction section, and updated wiring table
- Updated CLAUDE.md with LP5562 EN wired-AND topology docs
- Updated STATUS.md with hall sensor decisions and hardware inventory
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Integrate LP5562 driver from sibling project (ntag5-samd21-lp562)
with full doc comments restored
- Update main.rs with complete M1 test: I2C init, GPIO EN, RGBW cycle
- Rewrite DEVELOPMENT_PLAN.md from waterfall to milestone-based groups
organized by hardware availability (Groups A-E)
- Rewrite STATUS.md with milestone checklist tracking
- Add LP5562 timing constraints and flash script docs to CLAUDE.md
- Add flash_when_ready.sh for auto-flash dev workflow
- Add brainstorm design doc for plan redesign rationale
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Set up Rust embedded project targeting SAMD21 (thumbv6m-none-eabi) with
XIAO M0 BSP for dev board prototyping. Includes LP5562 EN pin control
on D0/A0, project documentation (README, CLAUDE.md), phased status
tracker, and detailed development plan covering LP5562 driver integration,
NTAG5Link I2C driver, pattern storage format, power management, NFC
communication protocol, recovery mode, and firmware update strategy.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
