Designed the smart espresso scale schematic and renamed the project Smart Espresso Scale. The schematic now has 55 components / 44 nets, including USB-C power/ESD, BQ24295 Li-ion charger/power-path, 3.3 V regulation, ESP32-S3 BLE MCU, NAU7802 load-cell AFE, microSD logging, I2C OLED display, buttons, and status LEDs; verification found no open ERC/component/footprint errors in the checked categories.

Project files created:

Open items:

Select the final Li-ion cell capacity and set BQ24295 charge current accordingly; firmware currently notes a conservative ≤512 mA target.
Validate TLV1117 dropout/thermal margin during BLE + display + SD write bursts.
Verify the exact OLED/display module pinout and 3.3 V compatibility before production.
PCB layout still needs antenna keepout, charger/regulator thermal layout, and load-cell analog routing care.

Suggested next steps:

Proceed to PCB board size/constraints and component placement.
Choose the final battery capacity and enclosure/display mechanical constraints.
Run PCB layout with ESP32 antenna keepout and load-cell analog separation.
After placement, route and run full DRC/PI/SI checks.

Layout and fix risks

Proceed to layout

Fix open risks

Set design constraints

Run schematic review

Refine this doc

Ask about this doc

Technical Construction File — Smart Espresso Scale

Status

Draft

Applicable Regulations

FCC Part 15 intentional radiator / modular transmitter integration review
CE RED / EMC / RoHS review
ISED/UKCA as needed for target markets

Product Description

Battery-powered smart espresso scale with ESP32-S3 BLE connectivity, USB-C charging, local microSD logging, load-cell measurement, and integrated display.

Wireless Technology Summary

Table

Module	MPN	Technology	Frequency Band	Pre-certified?	Notes
`U4`	ESP32-S3-WROOM-1-N8R8	Bluetooth LE / Wi-Fi capable module	2.4 GHz ISM	Module certification must be verified for exact ordering code	Firmware should disable unused Wi-Fi if product is BLE-only

Required Documentation Checklist

Block diagram: see Block Diagram project file.
BOM: available from current Flux BOM.
Firmware starter: see Firmware Starter project file.
Final schematic PDF export.
Final PCB layout/Gerbers after layout.
Module grant/FCC ID and antenna integration evidence for the exact ESP32-S3-WROOM-1-N8R8 ordering code.
EMC/RF test reports from accredited lab.
Final user manual with regulatory statements.

RF Design Notes

Preserve the ESP32-S3 module antenna keepout during PCB layout: no copper, components, or traces under/near the antenna area per Espressif module layout guide.
Use the module as integrated; do not change antenna type unless re-certification impact is reviewed.
Keep high-current charger/regulator loops away from the antenna region.

Declaration of Conformity Draft

We, [Company Name], declare that the Smart Espresso Scale is designed to conform to applicable FCC Part 15 and CE RED/EMC/RoHS requirements when manufactured with the approved BOM, PCB layout, firmware configuration, and ESP32-S3 module integration conditions.

Authorized signatory: ____________________ Date: ____________________

Open Items

Confirm final markets and regulatory labels.
Verify the exact module FCC ID / CE documentation for the purchased ESP32-S3-WROOM-1-N8R8 module.
Complete layout-dependent antenna keepout review before manufacturing.

Status
Applicable Regulations
Product Description
Wireless Technology Summary
Required Documentation Checklist
RF Design Notes
Declaration of Conformity Draft
Open Items

Reviews

Documents

Project Specification — Smart Espresso Scale
Block Diagram — Smart Espresso Scale
Reference Recreation Ledger — Smart Espresso Scale
Power Budget — Smart Espresso Scale
Firmware Starter — ESP32-S3 Smart Espresso Scale
Board Bring-Up Plan — Smart Espresso Scale
Technical Construction File — Smart Espresso Scale
Safety Analysis — Smart Espresso Scale
Preliminary FMEA — Smart Espresso Scale

Assets

No assets added.

Project Name

Smart Espresso Scale

Description

BLE smart espresso scale with USB-C power, single-cell Li-ion battery charging, load-cell measurement, local data logging, and an integrated segment/display interface.

Properties

Properties describe core aspects of the project.

Pricing & Availability

Distributor	Qty 1
Arrow	$3.59–$4.32
Digi-Key	$1.90
HQonline	$1.48–$1.72
LCSC	$13.57–$14.21
Mouser	$15.81
TME	$7.01
Verical	$1.51–$2.05

Controls

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ryanf / Smart Espresso Scale

Files