I reviewed the completed research handoffs and checked the live schematic and PCB. This revision is still incomplete and remains on release hold—not an approved battery-powered design.
Recorded your CNHL 3S battery requirements and researched battery monitoring, default-off protection, auxiliary supplies and a purchased motor converter.
Documented integration gaps and saved the verified continuation state in the revision handoff.
What remains unresolved
Motor power: no battery-protection or high-current motor-power circuit was added. The proposed TRACO converter is not selected or approved: exact-model capability and low-input thermal derating remain unconfirmed. FET/shunt sizing, fuse coordination, current limits, regeneration handling, harness losses and transient/thermal validation are unfinished. The 25–30 A option remains provisional capacity—not continuous demand—and D24V150F5 remains unsuitable for unrestricted 25–30 A service.
Face: still disabled. U4’s head-side supply remains unsourced, and EN remains pulled low.
C7/C8/C13: still generic capacitors without exact qualified MPNs; effective-capacitance/ESR qualification is unfinished.
Integration: firmware compatibility, audio tests, exact harness drawings and mechanical fit remain incomplete. The PCB is still the unapproved 160 × 100 mm placeholder.
Checks: the eight ERC categories returned by my inspection passed, but this was not a complete final sign-off. DRC still reports unrouted connections. No manufacturing files were released.
What I still need from you
Original/restored torso and head CAD, including mounting locations and cable-clearance requirements.
Photos of the received battery label and balance connector; installed harness lengths and cooling conditions.
Where not already supplied: exact head/display and Jetson-carrier revisions, plus the target firmware repository and commit. Joint duty/torque requirements are also needed if reduced-current operation is acceptable.
You do not need to resend the motor model or battery product identity. Execution stopped because your account ran out of ACUs.
@power-budget~c0 is the authoritative current motor capacity/options/margin and validation assessment.30A/150W is PROVISIONAL capability only, not normal demand or approved hardware; D24V150F5 is not approved for unrestricted25–30A. The existing communications-only wiring boundary below is unchanged. Exact EH/cable21AWG versus generic crimp22AWG qualification, protected external distribution, thermal/drop/fault/regen and USB-live motor-off tests remain open. RELEASE HOLD; no schematic/PCB/manufacturing changes in this records-only assessment.
Disposition and saved version
Electrical migration completed; protected motor power and safe commissioning remain BLOCKED, and the PCB is NOT fabrication-ready. No fabrication order or manufacturing export was made.
Before edits, saved independent Microcat Torso Pre-U2D2 Backup. Original baseline commit #64d76872, electrical reference #d2bd7bbf. Work targets the original project, not the backup. Owner request: U2D2 revision brief.
The source was a partial unrouted capture, not a completed PCB. There were no captured motor regulator, input/branch protection, current/cell monitoring, high-current disconnect or regeneration absorber to preserve. Their absence remains explicit; this migration does not claim that hardware exists.
Actual schematic and BOM changes
Removed exactly 16 components: U5, U6, U7, Q1, Q2, J7, R4, R5, R6, R7, R8, R9, R23, C17, C18, C19. These were exclusively the MCU motor-master TX/RX, OE/direction sink, arm shunt and support parts. Q1/Q2 were logic OE switches, NOT motor-power switches.
Retained/repurposed J6 as a passive custom diagnostic tap: 1 GND, 2 NC, 3 TTL_DATA; TP5 remains passive DATA access. J4 pins 5 and 6 are now NC, not motor logic power or safety permission. U1 PA9, PA10 and PB0 are explicitly NC. No replacement transceiver or USB-UART IC was added.
RS-485 and duplicated USB-serial circuitry were absent in the inspected baseline inventory; therefore none were removed. Unrelated purchased head-board USB circuitry is untouched.
Table
Metric
Baseline
After migration
Native component instances
88
72
Native grouped part types
17
16
Populated electrical nets
54
44
Net records
61
61
Empty net records
7
17
PCB route segments / vias
0 / 0
0 / 0
Ten former motor net names remain as empty identifiers because the net-deletion tool rejected their inspected IDs after two attempts. They have no connections and no remaining drawn wires. Six obsolete NC wire stubs and detached motor-block visual residue were removed without changing valid connectivity. Do not interpret empty legacy names as functioning circuitry.
Preserved subsystems and slave-interface decision
U1 is NOT a Dynamixel-bus slave in this design. Its independent host UART and IMU link were preserved:
U1 PA2 -> U18 -> U9 -> Jetson J1 pin 10.
Jetson J1 pin 8 -> U17 -> U8 -> U1 PA3.
U1 PA4/PA5/PA6/PA7 -> local LSM6DSV16X SPI; PC0/PC1 -> IMU interrupts.
MCU supplies, SWD, reset/boot, UART buffers/pulls and all audio/face connections remain electrically unchanged except shared rail membership losing deleted components.
MAX98357A, microphone option, audio buffers, face isolation placeholder and all actual remaining power boundaries were preserved. The face link remains disabled as before; preservation is not functional validation.
Passive wiring diagram
This is a reviewed connection specification, NOT an approved fabricated cable or protected power stage.
Text
Jetson USB host --> revision-correct USB cable --> purchased ROBOTIS U2D2
U2D2 TTL pin 1 GND -------------------- external distribution reference GND
U2D2 TTL pin 2 ---- OMIT CONTACT/WIRE; individually insulate, NO motor 5V
U2D2 TTL pin 3 DATA -------------------- shared DATA --> each motor pin 3
REQUIRED EXTERNAL POWER STAGE — NOT IMPLEMENTED/QUALIFIED:
protected nominal 5V source --> independent hardware power disable
--> coordinated branch protection --> motor pin 2
qualified source return --> external return distribution ----------> motor pin 1
OPTIONAL PCB DIAGNOSTIC SPUR, NOT motor power:
external reference GND --> J6 pin 1
DATA ------------------> J6 pin 3 --> TP5
J6 pin 2 --------------> NC / omit terminal and wire
Keep GND and DATA distinct. Motor feed AND return must bypass J4/J6 and PCB signal-ground traces. USB ground must not become a motor-load return. Evaluate open-return faults and alternate return paths through USB/reference wiring before connection.
Official manufacturer manuals specify the standard TTL motor pinout 1 GND / 2 VDD / 3 DATA. The documented two-wire U2D2 harness physically omits pin 2 so it cannot join motor power to U2D2, regardless of ambiguity between the general connector table and the device pinout graphic. Actual revision/cavity continuity is still required. Manufacturer references: U2D2 e-Manual and XL330-M288 e-Manual; ROBOTIS separate-supply guidance.
Connector distinction: motor/U2D2 harness is EH-family; the existing diagnostic J6 is PH-family and is NOT a drop-in mating connector. Use qualified purchased ROBOTIS cables or validated EHR-3 / SEH-001T-P0.6 harnessing. Do not use assumed cable colors or left/right views; confirm keyed cavity numbering and wire-entry/mating views before assembly.
Current capacity and power-off gate
The manufacturer-source reviews report XL330-M288-T nominal-5V stall current 1.47 A per motor; 15 simultaneous published stall points total 22.05 A / 110.25 W, not normal walking demand or a continuous converter rating. See the exact operating conditions in the linked official XL330 manual and detailed execution report. Actual transient, normal-load and regeneration measurements remain unavailable.
JST EH's catalog current rating is 3 A AC/DC with AWG22. Two nominal stall loads would total 2.94 A before temperature/contact derating; fifteen must never pass through one small EH contact. Per-motor distribution is a conservative starting point, not an approved fuse/gauge/connector design. Cable length, grouping, thermal rise, contact derating, fault current and fuse coordination must determine final branches. Do not put unqualified larger wire into an incompatible crimp terminal.
U2D2 supplies communications, NOT motor power. Omitting VDD does not guarantee that DATA cannot parasitically energize an unpowered motor. No applicable manufacturer powered-off DATA leakage guarantee was established. There is no added galvanic isolation or zero-backfeed claim.
Service rule pending validation: connect/change wiring only with all power off; establish qualified motor supply/reference before enabling USB communication; stop commands and disconnect U2D2 USB before normal motor-power removal. Emergency motor-power cutoff can still occur while USB is alive—this requires a measured power-state test and reviewed safety solution, not a software-only sequence. No powered robot commissioning is authorized.
Required but absent; no arbitrary high-current parts ordered
Purchased U2D2 is included in this SYSTEM BOM, not silently added to the native 72-component PCB assembly BOM. No usable verified U2D2 library part was found in two searches; a missing-part request was submitted by the capture tool. An unverified placeholder/footprint was not fabricated. Physical mounting, exact purchased revision and clearance remain unvalidated; no extra custom PCB is required.
Layout preservation and cleanup
Deletion triggered automatic fallback placement reflow of 38 unaffected components. This was corrected in #66f3bef9: all 72 retained component positions were explicitly pinned to their original baseline poses, read-back matched every surviving pose, all Top / 0 degrees. Rectangle 160 x 100 mm, existing four-layer 1.30 mm stackup and outline were preserved exactly. Those inherited poses include out-of-board parts and are NOT approved placement. No routing existed before or after; deleted footprints are absent and there is no stale routed copper.
Visual cleanup removed six affected netless wire stubs plus detached vertices; valid IMU/UART/audio/face labels and passive TTL_DATA remain. Obsolete empty net records are harmless but still require a platform cleanup capability; they were not repeatedly retried.
Fresh verification and independent review
Independent electrical review found no migration-induced pin/connectivity error and confirmed the exact removal list and preserved separate IMU UART. Lead fresh checks after restoration/cleanup:
ERC: 0 errors, 0 warnings, 10 returned categories, 2026-10-19 16:20:37 UTC.
50 outside-board warnings and 1 J1/J3 body-overlap warning (0.23 mm²) retained at the prescribed baseline positions.
Missing footprints, invalid layer, redundant trace, overlapping copper and keepout checks returned success. This does NOT approve actual footprint geometry or overall DRC.
Firmware/software delta
Jetson becomes sole motor-bus owner through ROBOTIS DYNAMIXEL SDK and actual U2D2 USB serial identity. Use /dev/serial/by-id or an explicit verified udev rule, not hardcoded /dev/ttyUSB0; do not invent VID/PID/serial. Confirm protocol/control table, baud, unique IDs, response timing and one-motor operation before group traffic.
Remove STM32 USART1 motor master, PA9/PA10 TX/RX/DMA handling, PB0 direction/OE request and deleted arm/permission logic. Retain USART2 PA2/PA3 IMU telemetry and local IMU SPI/interrupts. Configure removed MCU pins as safe unused inputs/analog. The MCU is not a DXL slave and no slave interface was deleted. Reserve legacy motor ABI fields as unavailable, as documented in Firmware Interface Specification.
No firmware source/binary, USB test, motor test or power-off test was executed. U2D2 commands, torque-disable packets and USB loss do not substitute for independent motor-power disable.
Remaining items and next actions
Design and review actual protected motor power, fault/undervoltage monitoring, independent disconnect and regeneration handling from battery/load/harness data. These were missing before this migration.
Validate the actual USB/U2D2/motor revision, keyed harness, load return paths and USB-on/motor-off leakage, including emergency cutoff.
Qualify C7/C8/C13, complete face isolation and target firmware/audio tests; obtain robot CAD for real placement and U2D2 mount.
Approve a separate physical placement/routing phase only after the above scope is ready. No fabrication order.
Detailed capture and source evidence: execution report. Its position-restoration and visual-residue blockers are historical and superseded by the verified corrections above; its missing protected-power/native-library/off-state limitations remain current.