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Phase 3 — Power the IMU

Four wires: IMU supply plus CS / SDO address straps. TFT power from Phase 2 stays. No I2C data yet.

Firmware

Unchanged — firmware/01-hello/.

Preconditions

Checkpoint 2 passed. IMU VDD…CS header on. Unplug USB while seating jumpers.

Warning

Power the IMU from 3V3 only — 5V on the logic can kill the module. After wiring, check for heat and ~3.3 V on VDD before trusting it.

Wires

Phase 3 — IMU power

From S3 To
3V3 IMU VDD, IMU CS
GND IMU GND, IMU SDO

S3 underside — match silk. CS→3V3 and SDO→GND set I2C address 0x6A for the next phase. Leave IMU SCL / SDA and the left row open.

Check

Plug COM. IMU cool. Meter ≈ 3.3 V on IMU VDD and IMU CS. TFT backlight still on. Hello still prints.

pio device monitor -b 115200 --port /dev/ttyACM0

seismo hello MAC=28:84:85:8C:D0:40 uptime_ms=5080613

Checkpoint 3

  • [x] Those four IMU wires only (TFT power still on)
  • [x] ~3.3 V on VDD and CS, no heat
  • [x] Hello still prints
  • [x] Lab log

Next: Phase 4 — I2C scan