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.
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
A momentary or non-latching switch which causes a temporary change in the state of an electrical circuit only while the switch is physically actuated. SWITCH TACTILE SPST-NO 0.05A 24V