ADS7128 Begin + Communication Test
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Test 1: I2C device present at 0x10
  PASS: Device found

Test 2: begin() succeeds
  PASS: begin() returned true

Test 3: GPIO round-trip (CH0 out -> CH1 in)
  CH0=HIGH, CH1=HIGH ... PASS
  CH0=LOW, CH1=LOW ... PASS

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RESULTS: 4/4 tests passed
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