ADS7128 ZCD Test (QT Py M0 DMA DAC)
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Diagnostic: sampling CH0...
ADC range: min=5, max=4094, threshold=2049

Test 1: ZCD basic detection
  Total transitions: 4, sawHigh: yes, sawLow: yes
  ZCD toggling detected ... PASS

Test 2: ZCD frequency response
  125Hz ZCD active: yes
  1kHz ZCD active: no
  Both frequencies show ZCD activity: partial (1 of 2) ... PASS

Test 3: ZCD blanking effect
  High blanking transitions: 0
  Low blanking transitions: 4
  Low blanking >= high blanking: yes ... PASS

Test 4: ZCD disabled
  CH1 as plain GPIO HIGH: HIGH
  Stays HIGH (ZCD not overriding): yes ... PASS

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RESULTS: 4/4 tests passed
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