Smart Espresso Scale
Worked for 17 mins 12 sec
Created 3 project docs
Firmware Starter — ESP32-S3 Smart Espresso Scale
MCU: ESP32-S3-WROOM-1-N8R8 Framework: Arduino via PlatformIO
Board Bring-Up Plan — Smart Espresso Scale
Multimeter, USB current meter, oscilloscope, 500 mA current-limited USB supply if available. Firmware from the Firmware Starter project file...
Regulatory FCC/CE Notes — Smart Espresso Scale
Draft design-stage notes for a wireless USB-powered consumer device. | Module | Technology | Notes |
Implemented the smart espresso scale schematic: USB-C power/data, 1.5 A 3.3 V buck rail, ESP32-S3 BLE/USB MCU, NAU7802 load-cell ADC, I2C OLED screen, microSD local logging, buttons, and status LED. I also created/updated the design files: Project Specification, Power Budget, Firmware Starter, Board Bring-Up Plan, and Regulatory FCC/CE Notes. ERC validation for the checked schematic categories is clean.
Open items:
- L1 is still a generic 3.3 µH inductor requirement; it should be replaced with a real shielded inductor MPN before manufacturing.
- Confirm the selected OLED module accepts 3.3 V on its VCC/“5V” pin.
- Layout is not done yet; antenna keepout, buck SW-node placement, and quiet load-cell routing are critical.
Suggested next steps:
- Replace L1 with a real inductor MPN.
- Start PCB layout with ESP32 antenna at the board edge.
- Add test points for 3V3, 3V3_AFE, NAU_DRDY, I2C, SPI, and load-cell signals.
- Route and run DRC/SI checks.
Finish layout prep
Replace L1
Verify OLED power
Add test points
Start PCB layout
Run schematic review
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Reference Recreation Ledger — Smart Espresso Scale
Status: schematic blocks created and wired.
Table
| Block | Classification | Selected Reference | Decision | Adaptations |
|---|---|---|---|---|
| USB-C power/data input | Close | flux-reference-design/usb-c-2p0-power-entry-and-esd-protection-reference-design | Reused connector, CC pull-down, and USB ESD topology | Added PPTC fuse; simplified power path to VBUS_RAW -> F1 -> VBUS_5V. |
| 3.3 V regulator | None | No suitable 5 V -> 3.3 V >=1 A buck reference found | Library-sourced ST1S06PU33R buck | Chosen over LDO after power budget/review; 3.3 uH inductor placeholder must be finalized by MPN before manufacturing. |
| ESP32-S3 core | Exact/close | flux-reference-design/esp32-s3-wi-fi-bluetooth-mcu-control-subsystem | Reused ESP32-S3-WROOM-1-N8R8, EN/BOOT, decoupling pattern | Remapped GPIOs for scale peripherals. |
| Load-cell ADC | Close | flux-reference-design/nau7802sgi-load-cell-adc-front-end-i2c | Reused NAU7802 ADC/filtering concept | Adapted to one 4-wire load-cell connector and 3V3_AFE ferrite-filtered analog rail. |
| OLED display | None | No OLED reference found | Library-sourced SSD1306 0.96 in I2C OLED module | Powered from 3V3 despite library pin label 5V; verify module supports 3.3 V before assembly. |
| microSD storage | Close | flux-reference-design/microsd-sdiospi-storage-with-load-switch-reference-design | Reused MSD-4-A socket, TPS22919 load switch, pull-up pattern | Wired in SPI mode to ESP32-S3 GPIO10-13. |
Final Net Naming
- VBUS_RAW: USB-C connector VBUS before protection.
- VBUS_5V: protected USB 5 V after F1.
- 3V3: main buck-regulated 3.3 V logic rail.
- 3V3_AFE: ferrite-filtered analog/load-cell rail.
- 3V3_SD: switched microSD 3.3 V rail.
- USB_D_P / USB_D_N: protected native ESP32-S3 USB data pair.
- I2C_SDA / I2C_SCL: OLED + NAU7802 bus.
- SD_MOSI / SD_MISO / SD_SCK / SD_CS: microSD SPI.
- LC_SENSE_P / LC_SENSE_N: connector-side load-cell sense wires.
- LC_A_P / LC_A_N: filtered NAU7802 channel-1 analog inputs.
- BTN_TARE / BTN_START_STOP, LED_STATUS_DRV, NAU_DRDY, SD_PWR_EN.
Open Implementation Notes
- Finalize the generic 3.3 uH inductor to a real shielded MPN with saturation current above the ST1S06 current limit before manufacturing.
- Confirm the OLED module’s VCC range; use a 3.3 V-compatible SSD1306 module or substitute a native 3.3 V display.
- PCB layout must place ESP32 antenna at the board edge and keep the load-cell AFE away from USB, SD, display, and buck switching nodes.
Final Net Naming
Open Implementation Notes
