Frozen Placement DRC Routing
Thought for 2 mins 2 sec
I’ll continue from the current partially routed board with the new permission: small local moves are allowed in the USB/display/power areas, then I’ll route and verify DRC.
Worked for 7 mins 46 sec
The local placement pass unexpectedly nudged U3 despite the instruction not to move it, so I’m restoring that mechanical constraint first and then cleaning up the stale trace issues before routing.
Thought for 29 sec
I read the attached routing instructions, inspected the current board state, and confirmed the board still had 48 airwire DRC errors before making changes. I then ran a small-local-placement pass intended to open routing channels, but it unexpectedly nudged U3 despite the “do not move U3” constraint and introduced overlapping copper from stale routing.
Open items:
- Restore/verify U3’s intended placement and antenna keepout.
- Clean up the newly introduced overlapping copper/stale traces.
- Continue routing remaining airwires.
- Add/verify GND pours and run final DRC.
I’m blocked from continuing because the account currently has no available ACUs, so AI execution tools are unavailable right now.
Restore U3 cleanup
Prioritize DRC errors
Remove stale traces
Verify U3 placement
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Schematic Notes — Mini Retro TV
Status
Schematic V1 is captured and ERC checks are clean for the selected review categories. Layout has not started yet.
Key Architecture Decisions
- ESP32-C3-MINI-1-N4 bare RF module is used instead of an ESP32 dev-board footprint.
- A dedicated XC6220B331MR 3.3 V LDO was added because ESP32-C3-MINI-1 requires 3.0–3.6 V on VDD33 and cannot be powered directly from a LiPo cell.
- MCP73831-2-OT charge current is set to about 200 mA using 5 kΩ on PROG.
- MCP73831 STAT drives a red charge LED and a green complete LED using the tri-state status behavior of the MCP73831 variant.
- Exactly 3x US1881 Hall latches are included as requested.
Important Caveats
- US1881 minimum supply is 3.5 V. They are powered from VSYS, so cassette detection is not guaranteed when the LiPo falls below about 3.5 V.
- MCP73831 has no power-path/load-sharing. Charging is most accurate when the slide switch is OFF and the system load is disconnected.
- Display header pinout is assumed: 1 VCC, 2 GND, 3 SCK, 4 MOSI, 5 CS, 6 DC, 7 RST, 8 BLK.
- Backlight assumes BLK is a low-side/cathode-style backlight control input that can be switched by Q1.
Power Nets
Table
| Net | Purpose |
|---|---|
| VBUS_RAW | USB-C VBUS before fuse |
| VBUS | Fused/protected USB 5 V to MCP73831 |
| BAT+ | LiPo positive and MCP73831 BAT |
| VSYS | Switched battery system rail after slide switch |
| 3V3 | Regulated logic rail from XC6220B331MR |
| GND | Common ground |
ESP32-C3 Pin Map
Table
| ESP32-C3 Pin | Net | Function |
|---|---|---|
| IO18 | USB_DN_MCU | USB D- |
| IO19 | USB_DP_MCU | USB D+ |
| IO4 | TFT_SCK | ST7789 SPI clock |
| IO6 | TFT_MOSI | ST7789 MOSI/SDA |
| IO7 | TFT_CS | ST7789 chip select |
| IO5 | TFT_DC | ST7789 data/command |
| IO10 | TFT_RST | ST7789 reset |
| TXD0 / GPIO21 | BL_PWM | Display backlight PWM gate drive |
| O0 / GPIO0 | HALL0 | Cassette ID bit 0 |
| IO3 | HALL1 | Cassette ID bit 1 |
| IO8 | HALL2 | Cassette ID bit 2; pulled high by Hall output pull-up |
| IO9 | BOOT_GPIO9 | Eject button and BOOT strap/test pad |
| RXD0 / GPIO20 | BUZZER_PWM | Passive piezo PWM drive |
| IO1 | BAT_ADC | Battery voltage ADC divider |
| IO2 | GPIO2_STRAP | Boot strap pull-up/test pad only |
| EN | EN | Enable/reset RC and test pad |
Selected Main BOM
Table
| Designator(s) | Part | Function |
|---|---|---|
| U3 | ESP32-C3-MINI-1-N4(4MB) | WiFi/BLE MCU module |
| U1 | MCP73831-2-OT | LiPo charger |
| U2 | XC6220B331MR | 3.3 V LDO |
| J1 | USB4215-03-A | USB-C receptacle |
| J2 | B2B-PH-K-S | JST-PH battery connector |
| J3 | 1x8 2.54 mm pin header | ST7789 display connector |
| U4-U6 | US1881ESE-AAA-000-RE | Hall latch sensors |
| Q1-Q2 | AO3400A | Backlight and buzzer low-side drivers |
| BZ1 | CPT-9019S-SMT-TR | Passive piezo transducer |
| D2 | USBLC6-2SC6 | USB data ESD protection |
| F1 | 0ZCJ0050FF2G | USB VBUS PTC fuse |
Next Layout Assumptions
- Board: rectangular 2-layer FR4.
- Place USB-C at an outer edge, display connector toward screen side, JST accessible, Hall sensors in a cassette-alignment row, ESP32 antenna at board edge with copper keepout.
- Add silkscreen labels for BAT, DISP, Hall0/1/2, Eject/BOOT, USB, charge LEDs, and revision.
Status
Key Architecture Decisions
Important Caveats
Power Nets
ESP32-C3 Pin Map
Selected Main BOM
Next Layout Assumptions
