From 72a7594548ef34c1dfd15a81659806f98fa65c1c Mon Sep 17 00:00:00 2001 From: Mikkeli Date: Mon, 12 Oct 2026 15:54:17 +0900 Subject: [PATCH] BOM: decided: IMU outside the enclosure on one USB-A port, roll-cage mounted Co-Authored-By: Claude Opus 5.5 Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz --- docs/BOM.md | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/docs/BOM.md b/docs/BOM.md index bebc8a6..c2202f9 100644 --- a/docs/BOM.md +++ b/docs/BOM.md @@ -164,8 +164,10 @@ Header facts (carrier board spec SP-11324-001 v1.3, Table 3-3 and 5-3; raw copy plus a realign event, so a bad alignment can be corrected afterwards. Align on level ground: a slope becomes part of the mount. - I²C mode (`FF AA 62`) exposes the raw MPU6050 only (no angles) and needs 4.7 kΩ pull-ups. Not used; v24-0429 lists SDA/SCL as not connected. - **Mounting matters more than the sensor.** An IMU needs a rigid path to the body; a box on carpet, Velcro or isolators smooths the motion - and drifts. Under consideration: the IMU on **USB** (WT61 behind a 3.3 V USB-UART adapter, or a GNSS+IMU module such as the NEO-M8U over - USB-C), mounted apart from the Orin's box on the **roll cage**, clamped close to a foot or a joint rather than mid-span. + and drifts. **Decided (2026-10-12): the IMU lives outside the enclosure on one USB-A port** + (WT61 behind a 3.3 V USB-UART adapter now; a NEO-M8U over USB-C as the GNSS+IMU upgrade), mounted on the **roll cage**, clamped close + to a foot or a joint rather than mid-span. The header wiring above stays valid but is no longer the plan. A fault in the sensor now + lands on a USB port (0.5 A limit) rather than the header's 3.3 V rail. - **No reverse-polarity protection is documented.** A 4-way Dupont housing put on the wrong way round swaps VCC and GND. Check VCC and GND with a meter before first power-up.