I confirmed the warning comes from the IC2 VREF pad6 correction ruleset, which forces VREF’s position to X = 1.25 mm, Y = 0.95 mm using !important; it does not itself indicate an electrical error.
In Agent mode, I’ll try removing only the !important flags, verify that VREF stays at the corrected position, and recheck the warning—rather than deleting the pad correction blindly.
Final scoped follow-up — 2026-10-06 (supersedes status below)
Completed: Q1 SS8050 with R1=10k OE pullup to USB_3V3, R2=47k MAIN_3V3-to-base and R3=100k base pulldown; removed U13 OE-GND tie. Q1 numbered pins1 B/2 E/3 C verified by direct rendered Shikues page1. OE/base nets read back; local placement completed with zero new overlaps/keepout/out-of-bounds. U13 disabled IOZ maximum±1uA and VCC=0 Ioff±2uA verified. VIH=0.46VCC minimum/VIL=0.25VCC maximum verified. At assumedVBE0.7V base supply55.3uA/net48.3uA and OE sink330uA (forced beta6.83) provide provisional nominal margin, NOT guaranteed hot leakage/saturation acceptance. ICBO maximum100nA is at25C/35V only; collector leakage can feed base/mainrail through47k, so off-state injection must be measured. Off-state improvement is captured, not measured acceptance.
Failed/blocked: robust partial-rail control. STM809T library/source verified threshold3.00–3.15V,140–280ms release delay, but minimum threshold is below CH340C3.1V minimum; no numerical hysteresis guaranteed. Therefore rejected, not installed. Bounded fallback bare NPN allowed by lead; may enable during ramp/brownout. Exact alternative adjustable supervisor TPS3808 candidate lacked attached datasheet, exact SOT23 search missed; stopped without speculative part placement. Full partial-rail/backfeed acceptance remains a release blocker.
Completed: U4 manufacturer PDF direct sandbox fetch and rendered page4 establishes1−VIN,2+VIN,3−VOUT,4+VOUT. Instance symbolic numbers and actual pad order match,2.54mm pitch,1mm drills; wired1 GND/2 MAIN_5V/3 ISO_GND/4 ISO_RAW, no symbol mapping correction required. Physical purchased-label caveat remains (manufacturer says label takes precedence). Source: https://atta.szlcsc.com/upload/public/pdf/source/20241022/55345257292DE3FDB4994AACC72C4519.pdf ; visual evidence
https://cdn2.flux.ai/flux-comment-files/files/commentFileId-8c45caf78f0e824169beac958ef6066a40551773b287888f5ac912f5d33e75bd.png?GoogleAccessId=fleet-worker%40graviton-mvp.iam.gserviceaccount.com&Expires=4944860297&Signature=K4%2FQ8i235fVSgokZh2gN57Keol1m4lt0z%2BjKWkn8Wg%2BHR9m17Drt%2BU%2BdVDspl7LYdMQA4m7DEqhEU8ovN1xgdySrZ%2B8V4GGkECmin3HNVeEKkOctifZw2rdjQXZUfdYsYfhDtFH68usrP5K50GlP%2FOGUo40ceTZ%2Foy22B%2BKPwDdvNRTlSilMqkkppDCE0u98WWWR0fqO1BjurKoShLx90ZPu%2Bq1703ajMZ4M9UAEYH%2B3qzGJ4QyIAlWVCuh9wisak9UKLSlB%2B15%2B7K2X1iq%2BQqDLK1As4alTfrPj4G6gOmDoNbexkQUUb%2BeEZqAI0LzYmRwTSMuWXvPW0yvzR2FiJw%3D%3D . Ratings now read:5V4.5–5.5 input,24V output42mA max/4mA min,220uF maximum capacitance,1W; actual minimum-load/transient/thermal acceptance not measured.
Completed: narrow VREF overlap repair. Root cause IC2 library VREF pad6 wrongly atcenter(0,0), physically shorting VSS and SCL, NOT a valid same-net tie. Microchip page1 top-view confirms6 upper-right opposite1; moved ONLY that pad by consuming-project selector override to(1.25,0.95)mm, preserving existing land sizes/pitch. Ruleset38255e04-1fe6-4d13-8990-a7c9f82450a1. Overlapping Copper recheck at04:26:33.473Z returns no findings. Override warning remains intentional; full land-pattern/assembly audit remains open. Source visual
https://cdn2.flux.ai/flux-comment-files/files/commentFileId-eb7f23194126e88b3d0105f3bd9f6997774642b2f9cf55430dcba0b6e4fae13d.png?GoogleAccessId=fleet-worker%40graviton-mvp.iam.gserviceaccount.com&Expires=4944860654&Signature=foUexWpGB712AiSs9JdcLKQg9rJqDtKajSFYznFWEQp1bkYgTwbM9oHZo%2BYZpxwga6BI%2BnwnhuvLVdAMSS3mjp4tN4Qf87ZyjvVo5Khj6fAS7pflCSVVPKhvaxdoZwlnFSe6ZdiT0HiHVKPl8be9o4%2Fkwh1cAnSqH%2BSflrYIqGVLs6AUpZDI4SyHIv349wZT0%2Fn2GjtYfXtG71N5%2Ft0gDlnOGfVInLAPukLHZ%2Fh41e4FEs2IAthytsrSdEr0Wmkeo1f5xDc702bC2gciNXCKVdhH%2FyJ6tqIDYKF4kt5u8komMbvFkacMWyQCreH8aSst%2Bsb7Iap9RwXiQRDGt%2BCBIw%3D%3D . No full routing or fab-limit loosening.
Completed: final read-only summary109 components/112 net identifiers,GND101/ISO_GND21 distinct. ERC at04:26:12.592Z:14 Errors,0 Warnings (3 missing power U10/U7 SYS,D4VBUS;11 undriven including8 portVBUS and3 transistor bases). No remaining U4 floating errors. No NC masking. Empty legacy nets cleanup unattempted; no net-deletion API sought. Commits813c9e49 additions,a523347f wiring,dbe9f251 roles; targeted placement also reports existing4 unrelated overlaps and changed C45 power-stage corridor warning outside scope.
Completed: flat-load budget revision and all six document addenda. Unattempted: firmware/build/flash, hardware off-state/ramp/brownout tests, physical battery/model/TVS mounting audits, routing/export/certification. This finite second follow-up is complete, overall design remains NOT FABRICATION READY.
Status: PARTIAL / NOT FABRICATION READY. Authoritative revision 2026-10-06: approved dedicated charging and separate programming ports, no mode switch. This revision supersedes the previous single-port U1-module integration report.
Assigned batch results
Table
Item
Status
Evidence / remaining limitation
Dedicated charging USB capture
Completed electrically
J2 four VBUS contacts → CHARGE_USB_VBUS_RAW → F2 → CHARGER_VBUS/U11. Separate R31/R32 CC Rd, all grounds/shields GND; D3 data to U11 CHG_DP/DM only; D6 K fused charge VBUS, A GND. SBU1/2 NC. C30/C38/C39 on charger VBUS; C38=100nF, C39=1uF. Physical TVS polarity/clamp/fuse coordination not approved.
Remove mode-switch/load-switch architecture
Completed
Obsolete U6/S1 and old R14/R30 removed in 90545cde. S1 absent. U13 S=USB_3V3 (HIGH); port1 NC and disconnected from charger; OE remains GND. New R14/R30 are DIFFERENT generic 10k support resistors with reused designators, not the deleted mode/enable parts. Empty legacy USB_MODE_SELECT and CHARGER_INPUT_ENABLE nets remain with zero pins.
Flat ESP32-WROOM-32U replacement
Completed electrically
Added U14 exact 32U variant; MAIN_3V3 on VDD2, GND1/15/38/39. Direct fourteen GPIO memberships audited alongside old exports before old U1 removal. U1 removed in 26e8b4d7, so no inherited receiver/connector/bridge remains. Manufacturer metadata corrected to Espressif. External Wi-Fi antenna still required for 32U; J1 is the separate LoRa antenna.
Separate programming receptacle/bridge/logic supply
Completed electrically
J3 four VBUS contacts → USB_VBUS_RAW/F1 → USB_5V_FUSED/U16 IN. U16 TLV760 OUT1→USB_3V3; IN2→fused program VBUS; GND3→GND. USB_3V3 powers only U13 logic and C23, never U14/U15. J3 CC1/R16 and CC2/R17 independent. J3 duplicate data contacts → D4 → U13 common → port2 UART_DP/DM → U15 UD+5/UD−6. U15 VCC16/V3 4 are MAIN_3V3 only. J3 SBU1/2 NC. Newly staged duplicate CC resistors removed.
Reset/boot/autoprogram support
Completed electrically
R33 10k EN pull-up, C62 1uF EN delay; R14 10k GPIO0 pull-up. Q3/Q4 Shikues SS8050 pin1 base/2 emitter/3 collector. Q3 collector EN, emitter RTS, base DTR through R30 10k; Q4 collector GPIO0, emitter DTR, base RTS through R34 10k. ESPressif DevKitC drawing physically read. U15 TXD2→U14 RXD0 GPIO3; U15 RXD3→U14 TXD0 GPIO1. Firmware flashing untested.
Local support capacitors and role/group updates
Completed
C59=100nF U14; C24=100nF U15; C25=100nF U16 input; C23 existing100nF U16 output/U13; C63=10uF local MCU bulk (generic procurement/effective capacitance pending). Canonical reset/base roles and USB J2 Charging / USB J3 Programming groups recorded. Existing replacement C52–C58 and external R24 exclusions preserved.
Positive rail separation
Completed, netlist-level only
Read-only audit confirms charge VBUS, program VBUS, USB_3V3, MAIN_3V3 are distinct; no U16 output or USB VBUS pin joins MCU MAIN_3V3. GND99 pins and ISO_GND20 remain separate. This is NOT proof against semiconductor signal-pin backpower.
Power-off/backfeed acceptance
Failed / unresolved
U13 is powered from programming VBUS with OE permanently LOW. USB host data could reach unpowered MAIN_3V3-powered U15 when receiver is off; CH340C USB-pin power-off tolerance has NOT been verified. Require receiver-power-aware mux disable or authoritative tolerance evidence plus measured off-state injection/backfeed. Do not claim power-off isolation merely because positive nets are separate. U13 unpowered leakage/ESD-rail paths also require review.
Targeted PCB staging
Completed, not final layout
All15 new retained components moved inside existing160×100mm four-layer board; no resizing, stackup change, unrelated part movement or routing. Introduced U15/C24 overlap fixed by moving C24 to(-9,-30)mm. Read-only scene tree confirms all15 persisted positions. Last placement result: zero changed-part overlaps, zero keepout and zero out-of-bounds. Existing helpers are still spread out; decoupler loop distances and USB routing are NOT approved.
Final electrical / placement checks
Completed; design FAILS release
ERC26 Errors/0 Warnings at2026-10-06T04:07:17.173Z: U4 four floating, four missing power,18 undriven (connectors/power semantics and transistor bases through resistors). Selected DRC at04:10:14.544Z:2 VREF overlapping-copper Errors and4 existing clearance-only component Warnings (C31/C33,C32/C33,C44/C46,C45/C46). No newly staged-part body overlap remains. Not a full routing/DFM approval.
U4 isolated converter
Failed / blocked, unchanged
Actual supplied-part pin/pad mapping remains unsupported. All four terminals intentionally disconnected. Isolated analog section still has no operational supply.
Documentation revision
Completed
All six planning/review files updated with authoritative two-port architecture notes and revised acceptance limits; prior material retained only as historical context where explicitly labelled.
Schematic visual drafting
Failed / blocked
Electrical capture and named stubs are not finished schematic geometry. No visual arrangement API used; new symbols auto-staged far from existing symbols.
No functional, machine-safety, manufacturing or compliance completion claimed.
Direct MCU GPIO continuity
Table
U14 GPIO
Net
18
RADIO_SCK
19
RADIO_MISO
23
RADIO_MOSI
27
RADIO_NSS
14
RADIO_BUSY
13
RADIO_DIO1
4
RADIO_NRST
16
RADIO_RXEN
17
RADIO_TXEN
21
SDA_MAIN
22
SCL_MAIN
34
BAT_ADC
36 / SENSOR_VP
CHARGER_PG
39 / SENSOR_VN
CHARGER_STAT
GPIO map is unchanged from the connection guide. Original module export-continuity blocker is superseded by direct flat-pin wiring; actual fabricated hardware continuity is untested. Flash pins17–22 and unused GPIOs are deliberately externally NC; they remain connected to the module's internal flash where applicable.
Final read-only evidence
Schematic summary:105 host components,110 total net identifiers (including empty legacy/module nets). Exactly two USB4960 connectors J2/J3, one flat ESP32 U14 and one CH340C U15; original U1 and S1 absent. Charging fused rail7 pins; programming fused rail5 pins; USB_3V3 four pins; MAIN_3V3 24 pins. Receiver radio/I2C/status/ADC memberships read back after U1 removal. Positive rails remain distinct; GND99 and ISO_GND20. Ground-net numbers are total summary counts, not filtered counts.
Electrical commits:521744ff charge path/hard selection;17a615ed core additions;e82f8f02 passive staging;626b15d1 MCU map;ef2c6a3f program/reset;26e8b4d7 U1/duplicate-CC removal;e726446c and efe69e97 annotation corrections. Removal of old U1 eliminated inherited nested components but left empty net identifiers.
Manufacturer evidence and verification status
U13 select function supported: query result dsq_3839fd1a7492239d2990, sources src_md_7020ef41acb3d0f0 and src_md_48f3a7a8c42a7bc3; HIGH selects port2, OE LOW enables.
CH340C SOP16 mapping supported; pin16 VCC,4 V3,13 DTR,14 RTS. Library pin8 calls unused OUT# NC; intentionally left unused. Web pinouts with VCC7 or V3 16 were contradictory and rejected. 3.3V V3-to-VCC tie was read through web source but datasheet-tool claim remained cited_unverified, not independently machine-verified.
D5/D6 manufacturer pad polarity, TVS clamping coordination and hot-fuse derating remain unverified. No repeated pending query cycle.
Power and analog caveats
Existing budget is provisional: MAIN_3V3 639mA allowance was inherited-module-based and now must explicitly include U15 plus reset support; 20mA USB-overhead placeholder belongs to J3 logic only, not J2 charge demand. Existing full-charge plus peak example remains incompatible with nominal810mA charger input-limit setting. No current setting or power-path part has been resized. Rd does not grant arbitrary adapter current. U16 serves only mux logic, not ESP32 peaks. Battery/BMS/NTC, actual machine load, startup/link-loss output policy and isolated converter limits remain open.
Prior ideal analog surrogate verified only resistor transfer: gain≈1.999996, connector at5V DAC≈9.900970V unloaded beyond R10,9.803902V with100k external load,9.008991V with10k. These are hypothetical dummy loads, NOT machine requirements, and not real OPA197 stability/headroom or system validation. U5 provisional dissipation≈0.468W at24V remains a concern.
Lead handoff
Finite approved two-port/flat-receiver capture and targeted staging batch is complete, independent of overall design completion. Next safety-critical item is power-off data-path backfeed review/control; U4 mapping and physical TVS/footprint/cable audits remain separate blockers. Do not energize an unreleased assembly, connect to a welding machine, or export for production in this state.