Smart IoT Water Level Controller Design
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Thought for 15 sec
I’ll use these reference images to refine the documented architecture and PCB feature list, especially the single-board labels, touch/network edition, relay/protection zones, and user-control layout. I’ll update the project files rather than duplicating the long details in chat.
Worked for 1 min 28 sec
I updated the project requirements using the uploaded reference images and added a new Reference Image Assessment.
I also updated the Project Specification with the image-derived features: touch/network edition labeling, front-panel LEDs, five-key backup UI, relay/protection zones, and clear PCB service markings.
Start schematic design
Choose safe sensors
Add component list
Explain isolation boundary
Design HV board later
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Schematic Implementation Plan
Recommended First Schematic Revision
The safest first implementation should focus on a complete low-voltage ESP32 controller board with isolated connectors to the high-voltage power board. The high-voltage board should be designed after exact mains-rated components, contactor, current sensor, and enclosure strategy are chosen.
Functional Blocks to Implement
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ESP32 control core
- ESP32-S3 module preferred for native USB, Wi-Fi, OTA support, and enough GPIO.
- EN reset circuit, BOOT button, USB programming, 3.3 V decoupling, and antenna keepout.
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Power input and regulation
- 5 V isolated input from high-voltage board or external certified AC-DC module.
- 3.3 V regulator sized for ESP32 Wi-Fi peaks.
- Input/output capacitors per regulator datasheet.
- Test points for 5 V, 3.3 V, and GND.
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Tank and dry-run inputs
- Five tank level inputs: S1 20%, S2 40%, S3 60%, S4 80%, S5 100%.
- One dry-run input.
- Each external input needs protection, pull resistor, filtering, and connector labeling.
- Final circuit depends on sensor type: conductive probe, float switch, capacitive sensor, or digital module.
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Motor control output
- Low-voltage isolated relay/contactor command output.
- Driver transistor or optocoupler depending on coil/interface.
- Flyback diode for DC coils or snubber/MOV for AC coils.
- Connector to high-voltage contactor board.
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Voltage and current measurement inputs
- Isolated analog voltage-sense input from high-voltage board.
- Isolated current-sense input from CT or isolated Hall sensor.
- ADC scaling to ESP32-safe 0 V to 3.3 V range.
- Filtering and clamp protection.
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User interface
- 4.2 inch TFT touch display, preferably SPI.
- Buttons: Auto/Manual, Emergency Fill, Reset, Bypass.
- Status LEDs: Wi-Fi, Motor, Fault, Auto, Manual, Tank level if needed.
- Buzzer driver.
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RTC and settings storage
- DS3231 RTC on I2C.
- External EEPROM only if ESP32 NVS is not sufficient.
- I2C pull-ups: one pair for the entire bus.
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Expansion and service connectors
- Debug/programming connector or USB-C.
- Inter-board connector to high-voltage board.
- Labeled test points.
Datasheets Required Before Wiring
- ESP32-S3-WROOM module: pinout, power, boot, USB, antenna keepout.
- Selected 3.3 V regulator: input/output capacitors, enable pin, thermal limits.
- Selected USB-C connector or programming connector: pinout and footprint.
- Selected TFT module: supply voltage, interface, current, touch controller pins.
- DS3231 RTC: I2C address, decoupling, battery backup if used.
- Selected current sensor or CT interface: output scaling and isolation.
- Selected voltage sensor interface: output scaling and isolation.
- Selected relay/contactor driver or optocoupler: input current and output ratings.
Key Open Questions That Affect the Circuit
These decisions materially change the schematic and should be resolved before final wiring:
- Should the first board be the low-voltage logic board only, with the high-voltage board treated as isolated connectors?
- What exact tank sensor type will be used: metal conductive probes, float switches, capacitive probes, or digital sensors?
- Is the 4.2 inch TFT module 3.3 V logic SPI, 5 V module with level shifting, or parallel RGB?
- Is the pump switched by an external contactor coil? If yes, what coil voltage: 230 VAC, 12 VDC, or 24 VDC?
- Should programming use USB-C native USB on ESP32-S3 or an external USB-UART interface?
- Should current sensing use SCT013 CT input for safety, or ACS712 on the high-voltage board?
Suggested Direction If No Further Input Is Provided
Proceed with a low-voltage ESP32-S3 logic board design using:
- 5 V isolated input connector from high-voltage board.
- 3.3 V regulator for ESP32 and logic.
- USB-C for programming and optional 5 V bench power.
- SPI TFT connector.
- I2C DS3231 RTC and optional EEPROM footprint.
- Protected digital inputs for S1 to S5 and dry-run.
- Protected analog inputs for isolated voltage/current monitor signals.
- Optically isolated contactor control output connector.
This keeps the first PCB safer and avoids prematurely routing dangerous 230 VAC on the same board as beginner-level ESP32 logic.
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