lf.read() sent CMD_LF_SNIFF_RAW_ADC (passive sniff, reader field OFF), so it captured
only a dead field — a real hardware dump came back flat at 0x7e-0x80 (±1 count of ADC
noise) with no tag modulation, which is why LF identify found nothing. Reader-mode reads
must use CMD_LF_ACQ_RAW_ADC (SampleLF -> field ON) to power the tag and capture its load
modulation.
- read() -> CMD_LF_ACQ_RAW_ADC (field on); sniff() -> CMD_LF_SNIFF_RAW_ADC (field off),
no longer delegating to read(). Shared _acquire() packs the real lf_sample_payload_t
(PACKED bitfield samples:30/realtime:1/verbose:1 + cotag byte = 5 bytes) instead of a
bare uint32.
Tests: read() uses ACQ with a 5-byte payload and correct samples field; sniff() uses SNIFF.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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