06 - Foot IMU, then shank IMU

Prerequisite: Stage 5 accepted; ADC remains attached. Firmware: diagnostic-imu-one, then diagnostic-imu-two. Status: NOT TESTED.

Sequence overview | Exact contacts | 3D assembly

Add and test

Optional early check, any time after the carriers arrive: wire one carrier, then both, to the DevKit alone and run diagnostic-imu-bench-one / -two; keep each still for 60 s and record every VERDICT line. 6A: foot MIKROE-4237 carrier at 3.3 V, SPI jumpers verified. 6B: add shank. Test each in six static orientations and rotate one at a time. Capture separate INT1 lines. These diagnostics also run the ADC; they are not standalone IMU-only images.

Acceptance checks

• 6-foot: SPI JP2–JP4 1–2; 3.3 V; WHO_AM_I 0x47/readback; foot CS GPIO7 / INT1 GPIO16; correct axis signs
• 6-shank: Shank CS GPIO15 / INT1 GPIO17; 200 Hz ±2% per sensor over 60 s (datasheet internal clock ±1.5% at 25 °C, ±2% over temperature) (packets ÷ interval_us, or INT1 capture); tick_step_mean 4687.5 ±0.5% and mean host_us_per_tick 1.067 ±2% (32/30 µs ticks; if both read 5000 and 1.00 instead, report it: the firmware tick constant must change) per sensor over ≥60 windows; no FIFO/missing-IRQ/invalid-packet errors
• 6-stationary: ±16 g / ±2000 °/s configured; gravity axis ±1 g within ±0.1 g, cross axes within ±0.1 g; gyro per axis <5 °/s before calibration

Send for review

• VERDICT and BENCH lines from the IMU-only bench check
• WHO/readback serial results
• FIFO and interrupt counts over 60 s
• IMU lines with interval_us, tick_step_mean and host_us_per_tick
• six-face accelerometer means
• stationary gyro means
• axis photographs
• raw IRQ/SPI timing capture

No shared sensor clock is assumed. Counter wraps and different startup counts are normal; equal row numbers do not identify simultaneous foot/shank samples.

Continuous regression

Before power: inspect the changed wiring against the contact table and photograph it. After power: remeasure every connected rail at the load, verify no unexpected heat/current, and rerun the last accepted diagnostic. Repeat earlier affected tests whenever a supply, cable, firmware or grounding connection changes. Record failures and repairs; retain the previous accepted evidence.

If the gate fails

Stop acquisition and remove power before changing wiring. Disconnect only the last-added module and restore the last accepted configuration. Repeat its test. If it now fails, check the shared supply/ground and changed connections before replacing components. Never change multiple modules at once to chase a fault.

Results

Fill measurements.csv; retain raw instrument files alongside screenshots. Outcome starts NOT TESTED. Include units, uncertainty, instrument model/settings, source voltage/load, firmware hash and filenames. Mark unmet criteria FAIL; missing evidence PENDING. Submit the whole stage folder, including failures. A completeness check is not engineering approval.

Stage files

• New wires: exact endpoints copied from the existing wiring table; keep earlier accepted wires. Power-isolation and qualification instructions above override connection order within a stage.
• Probe contacts: available exact probe locations. An empty table means use the instrument instructions above.
• Fixture parts: staged discrete fixture components from the existing BOM; this is not a complete procurement list for modules, tools or consumables.
• Measurements and submission metadata.