I’m blocked because execution credits are exhausted, so I can’t modify the schematic or add components in this run.
Current project state:
No schematic changes were made.
Project is still empty: 0 components, 0 nets.
No datasheets, component library searches, wiring, or validation checks were performed.
What remains to be done when credits are available:
Rename/describe the project appropriately, e.g. “WiFi USB-C RS485 Water Flow Meter”.
Create a power architecture:
USB-C 5 V input with CC resistors.
USB ESD protection.
Input fuse/polyfuse.
5 V to 12 V boost converter for the RS485 ultrasonic sensor.
5 V or 12 V to 3.3 V regulator for ESP32 and logic.
Proper input/output capacitors and decoupling.
Add ESP32 module:
3.3 V supply decoupling.
EN/reset network.
Boot/programming strapping.
UART programming header.
WiFi antenna keepout notes for layout.
Add RS485 sensor interface:
RS485 transceiver powered at 3.3 V or 5 V depending on chosen part.
A/B differential pair connector to external ultrasonic sensor.
TVS/ESD protection on RS485 lines.
Biasing and termination as appropriate.
12 V sensor power output connector.
Add indicators:
Power LED.
WiFi/status LED.
Flow activity LED.
Add connectors:
USB-C input.
External sensor connector carrying 12 V, GND, RS485 A, RS485 B.
UART programming/debug header.
Verify:
Datasheet-recommended circuits for every IC.
Power budget, especially USB-C 15 W versus 12 V sensor current.
ERC review.
No unconnected IC power pins.
Decoupling on every active IC.
Create project documentation:
System specification.
Power budget.
Firmware pin map.
Board bring-up/test plan.
Important design note: the requirement says the ultrasonic sensor is powered from 12 V, while the board input is USB-C 5 V/15 W. That means the design needs a 5 V-to-12 V boost converter sized for the sensor current. The sensor’s actual current requirement is needed to select the boost converter safely.
Wirelessly connects nets on schematic. Used to organize schematics and separate functional blocks. To wirelessly connect net portals, give them same designator. #portal
General Purpose Thick Film Standard Power
and High-Power Chip Resistor
47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film
Features:
- RMCF – standard power ratings
- RMCP – high power ratings
- Nickel barrier terminations standard
- Power derating from 100% at 70ºC to zero at +155ºC
- RoHS compliant, REACH compliant, and halogen free
- AEC-Q200 compliant