docs(0011): record the wall-clocked hardware run — the board question… - #159
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… is answered 9134 Hz, 96 us mean, 37 ms worst iteration, SLP 12.0, with a GPS lock, logging and the camera recording. The instrument validates itself: 9134 Hz x 96 us = 87.7% of the second inside loop(), and SLP — computed by a different route — reads 12.0%. All fourteen slots sum to ~99.8. SLP 12% also settles what the previous build could not distinguish: the CPU is not sleeping through the second, so the loop genuinely runs at ~9 kHz and the old pegged rate was the display clamp rather than the timebase bug. There was no way to know that until the window was wall-clocked. Headroom, against the binding constraint (one iteration per 40 ms PVT frame): ~420x on the mean, 43x on the worst iteration against the 4 KB GPS ring, 108x against the watchdog. Nothing here justifies an nRF5340 on throughput, and SLP 12% caps what leaving the Arduino core could reclaim. Also records where the 88% goes — it is polling, not work. GPS is called 9134 times a second to service a 25 Hz stream; DSP renders 3 times and early-returns ~9000; BTN is six digitalReads per iteration with nobody touching a button. Rate-limiting the polls would reclaim most of it without changing silicon. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01CqENxo91S1VL3sM9PTWMf1
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… is answered
9134 Hz, 96 us mean, 37 ms worst iteration, SLP 12.0, with a GPS lock, logging and the camera recording.
The instrument validates itself: 9134 Hz x 96 us = 87.7% of the second inside loop(), and SLP — computed by a different route — reads 12.0%. All fourteen slots sum to ~99.8.
SLP 12% also settles what the previous build could not distinguish: the CPU is not sleeping through the second, so the loop genuinely runs at ~9 kHz and the old pegged rate was the display clamp rather than the timebase bug. There was no way to know that until the window was wall-clocked.
Headroom, against the binding constraint (one iteration per 40 ms PVT frame): ~420x on the mean, 43x on the worst iteration against the 4 KB GPS ring, 108x against the watchdog. Nothing here justifies an nRF5340 on throughput, and SLP 12% caps what leaving the Arduino core could reclaim.
Also records where the 88% goes — it is polling, not work. GPS is called 9134 times a second to service a 25 Hz stream; DSP renders 3 times and early-returns ~9000; BTN is six digitalReads per iteration with nobody touching a button. Rate-limiting the polls would reclaim most of it without changing silicon.
Claude-Session: https://claude.ai/code/session_01CqENxo91S1VL3sM9PTWMf1
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ctest --test-dir tests/build)clang-tidycleanChecklist
CHANGELOG.mdupdated under[Unreleased](if user-visible)ARCHITECTURE.md/CLAUDE.mdupdated (if a module or interface changed)tests/Related issues