Accelerometer-driven low-power mode (hardware, PCB only) - #47
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Accelerometer-driven low-power mode (hardware, PCB only)#47thePunderWoman wants to merge 1 commit into
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Adds a QMA6100P accelerometer (I2C, shared OLED bus) and enables host-commanded XBee pin-sleep, laying the hardware groundwork for a low-power mode: OLED off + XBee sleep after a short idle timeout (no buttons, no motion), full soft-latch power-off after a longer one. - QMA6100P chosen after checking JLCPCB's actual parts library: no candidate accelerometer is Basic-library, so it won on price, size, and standby current (500nA), which matters since it has to watch for motion through the whole low-power period. - Hand-authored symbol + footprint (no existing library part) — pad geometry pulled from JLCPCB/LCSC's own EasyEDA component data (LCSC C2887190), not estimated from the datasheet's low-res drawing. - New Accelerometer sheet, wired into the existing I2C bus and into a new GPIO46 (INT1) interrupt line so the MCU can light-sleep instead of polling for wake conditions. - XBee DTR moved off its permanent GND tie onto GPIO42 (SLEEP_RQ), so firmware can actually request/cancel pin-sleep instead of the radio being forced awake at all times. - Placed, routed, DRC- and ERC-clean. Firmware (driver, low-power state machine) and production file generation are follow-up work — this PR is hardware/schematic only. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Summary
Part selection rationale, full pin wiring, and decoupling details are documented in
PCB/GPIO_table.md's new Accelerometer section.Status / what's NOT in this PR
This is hardware/schematic only, opened as a draft to checkpoint progress. Still to come as follow-up work:
Test plan
kicad-cli sch erc— 0 violations🤖 Generated with Claude Code