Smart Espresso Scale
Thought for 10 sec
I’ll define the scale architecture and requirements, check for reusable reference blocks, and propose a concrete build plan before creating the schematic.
Worked for 5 mins 33 sec
Created 2 project docs
Project Specification
Status: Review A compact, phone-connected espresso scale for measuring dose and shot flow in real time. The unit runs from a single-cell LiP...
Functional Block Plan
Purpose: Main control, filtering, UI, BLE phone link, and firmware updates. Interfaces/nets: 3V3, GND, USB_D+/D-, I2C, SPI, buttons, ADC_DRD...
I defined the architecture, power budget, interfaces, and functional blocks in the Project Specification and Functional Block Plan. The design uses ESP32-S3 BLE, a NAU7802 load-cell ADC, OLED segment-style UI, SPI NOR logging, USB-C/LiPo power-path charging, and a 3.3 V system rail; suitable reference blocks were identified for the MCU, measurement, and charging sections.
Confirm this architecture and I’ll proceed with the complete schematic.
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Use SPI NOR
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Functional Block Plan
1. MCU, BLE, USB Data
- Purpose: Main control, filtering, UI, BLE phone link, and firmware updates.
- Interfaces/nets: 3V3, GND, USB_D+/D-, I2C, SPI, buttons, ADC_DRDY.
- Requirements: ESP32-S3 module, native USB, BLE 5, antenna keepout, boot/reset.
- Reference classification: Close — ESP32-S3 Wi-Fi Bluetooth MCU Control Subsystem. Correct MCU/support topology; pin allocation and unnecessary appliance-oriented signals must be adapted.
2. Load-Cell Analog Front End
- Purpose: Excite and digitize a 4-wire 2 kg bridge load cell.
- Interfaces/nets: LOAD_E+/E-, LOAD_A+/A-, I2C_SDA/SCL, ADC_DRDY, analog supply, GND.
- Requirements: 24-bit conversion, low-noise filtering, 80–100 Hz sampling, calibration stability.
- Reference classification: Exact/close — NAU7802SGI Load Cell ADC Front End I2C. Correct ADC and bridge topology; simplify from two channels to one and adapt supply rails/connectors.
3. USB-C, LiPo Charging, and Power Path
- Purpose: Accept USB-C 5 V, charge one LiPo cell, power the scale during charging, and generate system power.
- Interfaces/nets: VBUS, USB CC1/CC2, BAT, SYS, 3V3, charger status/I2C, NTC.
- Requirements: 500 mA nominal charge, input protection, NTC, power-path operation, low quiescent current.
- Reference classification: Close — BQ24295 Reference Design. Provides one-cell charging and power path but is oversized; current limits and optional OTG features will be adapted or a lower-power pin-compatible design direction selected during build.
4. Display and User Controls
- Purpose: Show weight, shot timer, flow, battery, and connection state; accept tare/timer/mode input.
- Interfaces/nets: 3V3, I2C, display reset, three GPIO buttons.
- Requirements: 128x64 high-contrast OLED, segment-style UI, low idle power, top/front mounting.
- Reference classification: None — no suitable curated display block found; design from scratch using a library-supported OLED module/connector and sealed-button interface.
5. Local Data Storage
- Purpose: Retain shot records without a phone and support later synchronization.
- Interfaces/nets: SPI_CLK/MOSI/MISO/CS, 3V3, GND.
- Requirements: 8–16 MB NOR, low standby current, circular wear-leveled log.
- Reference classification: None for selected topology — a curated microSD block exists, but dedicated SPI NOR better fits compactness, power, and splash-resistance goals; design from scratch.
6. Battery Monitoring and System Protection
- Purpose: Report state of charge and protect external interfaces.
- Interfaces/nets: BAT, I2C/ADC, charger status, USB/ESD, load-cell connector shield.
- Requirements: practical battery percentage, low-battery cutoff behavior, USB ESD, reverse/short protection as appropriate.
- Reference classification: Close/derived — charger reference covers charge status and NTC; battery gauge and remaining protection will be designed from scratch.
7. Mechanical and Test Interfaces
- Purpose: Connect load cell/battery, support manufacturing test, and fit a splash-resistant scale enclosure.
- Interfaces/nets: load-cell connector, battery connector, test pads, mounting holes.
- Requirements: board-edge USB-C, isolated analog region, RF keepout, accessible programming/test points.
- Reference classification: None — application-specific mechanical design.
Proposed Power Tree
USB-C 5 V → protected charger/power-path SYS; LiPo 3.0–4.2 V ↔ charger; SYS → low-IQ 3.3 V regulator → MCU, display, ADC, flash, gauge.
1. MCU, BLE, USB Data
2. Load-Cell Analog Front End
3. USB-C, LiPo Charging, and Power Path
4. Display and User Controls
5. Local Data Storage
6. Battery Monitoring and System Protection
7. Mechanical and Test Interfaces
Proposed Power Tree
