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e2e: ADC sample-rate test survives a loopback that reads 0 V at the ADC's range edge #66

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Merged
wardviaene merged 1 commit into from
Nov 8, 2026
Merged

e2e: ADC sample-rate test survives a loopback that reads 0 V at the ADC's range edge #66

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10 changes: 9 additions & 1 deletion packages/embeddedci/tests/e2e/test_e2e_pod.py
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Original file line number Diff line number Diff line change
Expand Up @@ -805,7 +805,15 @@ def toggle_dac(k): # a 5 kHz burst on even events, flat on odd ones
block = 100
counts = np.asarray(cap.counts, dtype=np.int64)
blocks = counts[: len(counts) // block * block].reshape(-1, block)
active = (blocks.max(axis=1) - blocks.min(axis=1)) > 800
# Each block's swing around its own middle, modulo 65536: on the analog module with the quad
# DAC the cal1 loopback reads 0 V at the top of the ADC's code range, where noise wraps between
# 65535 and 0 and a flat block would look like a 65535-count swing.
mid = np.median(blocks, axis=1, keepdims=True)
centred = (blocks - mid + 32768) % 65536 - 32768
swing = centred.max(axis=1) - centred.min(axis=1)
active = swing > 800
if not active.any():
pytest.skip("no DAC burst on the cal1 loopback: the DAC does not reach the ADC on this pod")
edges = (np.flatnonzero(np.diff(active.astype(np.int8)) != 0) + 1) * block
rate = host_clock_rate(edges, stamps)
assert rate == pytest.approx(cap.sample_rate_hz, rel=HOST_CLOCK_REL), (
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