Espressif ESP32-C3 Single-Core Wi-Fi & BLE 5 SoC
Wireless Handheld Colorimeter Wand
Overview
A compact, pen-style wireless colorimeter designed for portable quality control and field testing with mobile app integration.
Adrian KrakowskiSystem architecture
POWER
MCU
SENSOR
ACTUATOR
- MCU_WIRELESS → OPTICAL_SENSINGI2CReads raw colorimetric sensor registers and configures integration time.
- MCU_WIRELESS → ILLUMINATION_LEDPWMModulates LED driver current and flashes illumination during capture sequence.
- POWER_MANAGEMENT → MCU_WIRELESSPowerSupplies regulated power to the wireless MCU.
- POWER_MANAGEMENT → OPTICAL_SENSINGPowerSupplies clean regulated power to the optical sensor frontend.
Bill of materials
| Part number | Type | Component | Manufacturer | Package | Qty | Datasheet | Match |
|---|---|---|---|---|---|---|---|
| MCP73831 | POWER | Texas Instruments TPS62180 or MCP73831 Linear Li-Ion Charger with USB-C Manages single-cell Li-ion battery charging via USB Type-C and provides regulated 3.3V rail. | MICROCHIP | SOT-23-5 / DFN-8 | 1 | Matched | |
2 alternatives consideredAI verified | |||||||
| ESP32-C3-MINI-1-N4 | MCU | Espressif ESP32-C3 Single-Core Wi-Fi & BLE 5 SoC Executes colorimetric Delta E calculation and handles dual-mode wireless sync to cloud and mobile apps. | Espressif Systems | 53-SMD Module | 1 | Matched | |
2 alternatives consideredAI verified | |||||||
| TCS34725 | SENSOR | Texas Instruments OPT4048 or ams OSRAM TCS34725 Measures reflected chromaticity matching human eye CIE 1931 response curve. | Ams | — | 1 | Matched | |
1 alternatives consideredAI verified | |||||||
| AL8843SP-13 | ACTUATOR | Nichia Optisolis High-CRI White LED with ZXLD1350 Driver Provides stable 45°/0° optical geometry illumination for repeatable color measurement. | Diodes Incorporated | 8-SOIC (0.154", 3.90mm Width) Exposed Pad | 1 | Matched | |
Build guide
3-5 hoursIntermediate
1
Procurement & Preparation
- Source and inspect the core bill of materials including MCP73831 Li-Ion charger, ESP32-C3-MINI-1-N4 wireless SoC, TCS34725 color sensor, and AL8843SP-13 LED driver.
- Prepare the pen-style wand enclosure, ensuring the 45°/0° optical geometry internal light baffling and aperture tube are clean and free of dust or manufacturing debris.
2
Hardware Assembly & Wiring
- Solder the MCP73831 Li-Ion charger circuit and USB-C receptacle onto the power management section of the PCB, establishing the regulated 3.3V power rail.
- Mount and solder the ESP32-C3-MINI-1-N4 SoC and establish power connections delivering 3V3 and GND to the system.
- Connect the TCS34725 color sensor to the ESP32-C3 via the I2C interface, routing SDA, SCL, VCC (3V3), and GND signals.
- Wire the Nichia Optisolis High-CRI LED through the AL8843SP-13 driver, and connect the PWM control line (PWM_CTRL and GND) to the ESP32-C3 for stable illumination intensity management.
3
Firmware Setup
- Flash the custom firmware onto the ESP32-C3-MINI-1-N4 via the USB-C serial interface, incorporating the colorimetric CIE 1931 and Delta E calculation algorithms.
- Configure the dual-mode Wi-Fi and BLE 5 stack on the ESP32-C3 to enable seamless mobile app pairing and cloud synchronization.
4
Testing & Calibration
- Perform a white-tile calibration routine by placing the colorimeter wand onto a certified standard white reference tile to normalize RGB sensor gain and eliminate ambient light artifacts.
- Conduct final quality control tests by measuring standard chromaticity color charts and verifying that calculated Delta E values fall within acceptable tolerance limits (< 0.5 dE).
Document
Wireless Handheld Colorimeter Wand
A compact, pen-style wireless colorimeter designed for portable quality control and field testing with mobile app integration.
Executive Summary
This reference design defines the system architecture, critical component candidates, risk register, and validation path for Wireless Handheld Colorimeter Wand. It is a system-level design deliverable; verify critical claims with manufacturer evidence and prototype testing before production release.
Design Overview
Requirements Coverage
| Requirement | Architecture coverage | Status |
|---|---|---|
| LED-based color illumination and optical sensing | Pending validation | Needs verification |
| Bluetooth/Wi-Fi wireless data transfer to mobile and cloud apps | Pending validation | Needs verification |
| Rechargeable Li-ion battery power with USB charging | Pending validation | Needs verification |
| Item | Details |
|---|---|
| Product Type | Wireless Handheld Colorimeter Wand |
| Key Functions | LED-based color illumination and optical sensing, Bluetooth/Wi-Fi wireless data transfer to mobile and cloud apps, Rechargeable Li-ion battery power with USB charging |
| Power Source | Li-Ion Battery |
| Connectivity | Bluetooth, WiFi |
| Size | Handheld pen or wand style, compact |
| Environment | outdoor |
| Difficulty | Intermediate |
| Est. Time | 3-5 hours |
System Architecture
Power Topology: USB Type-C input feeds a linear Li-Ion charger IC (MCP73831 style) charging a single-cell Li-Ion battery. A low-dropout (LDO) regulator steps down the battery/USB voltage to a clean 3.3V rail for the ESP32-C3 SoC and optical sensor.
Module List
| Module ID | Type | Name | Function | Voltage |
|---|---|---|---|---|
| POWER_MANAGEMENT | POWER | Texas Instruments TPS62180 or MCP73831 Linear Li-Ion Charger with USB-C | Manages single-cell Li-ion battery charging via USB Type-C and provides regulated 3.3V rail. | 5V/3.3V |
| MCU_WIRELESS | MCU | Espressif ESP32-C3 Single-Core Wi-Fi & BLE 5 SoC | Executes colorimetric Delta E calculation and handles dual-mode wireless sync to cloud and mobile apps. | 3.3V |
| OPTICAL_SENSING | SENSOR | Texas Instruments OPT4048 or ams OSRAM TCS34725 | Measures reflected chromaticity matching human eye CIE 1931 response curve. | 3.3V |
| ILLUMINATION_LED | ACTUATOR | Nichia Optisolis High-CRI White LED with ZXLD1350 Driver | Provides stable 45°/0° optical geometry illumination for repeatable color measurement. | 3.3V |
Power Tree and Signal Interfaces
| From | To | Type | Interface / rail | Voltage |
|---|---|---|---|---|
| MCU_WIRELESS | OPTICAL_SENSING | power | I2C | 3.3V |
| MCU_WIRELESS | ILLUMINATION_LED | power | PWM | 3.3V |
| POWER_MANAGEMENT | MCU_WIRELESS | power | Power | 3.3V |
| POWER_MANAGEMENT | OPTICAL_SENSING | power | Power | 3.3V |
Design Schemes
Single-Chip Wireless SoC with Integrated Tristimulus Color Sensor ★
Utilizes ESP32-C3 wireless combo SoC paired with a high-precision digital RGB/XYZ color sensor and linear USB-C charging for an ultra-compact pen wand.
Trade-offs: Optimized for minimal PCB footprint and lowest BOM cost, meeting the <25mm diameter target at the expense of custom multi-channel discrete spectral separation.
Dual-Processor Multi-Spectral Sensor Architecture
Employs a dedicated low-power sensor controller paired with an external Wi-Fi/BLE module, using a multi-channel spectral sensor.
Trade-offs: Offers advanced spectral curve breakdown and hardware decoupling, but increases PCB footprint and exceeds the tight wand diameter target.
Key IC selection
main wireless MCU for compute and comms
- Need: Execute Delta E color calculations locally and stream data via BLE/Wi-Fi with low power consumption in a compact form factor.
- Class: RISC-V 32-bit single-core SoC with integrated 2.4GHz Wi-Fi and Bluetooth 5 (LE)
- Shortlist: Espressif ESP32-C3 series, Nordic nRF5340 (requires external Wi-Fi chip)
- Pick: Select exact ESP32-C3 QFN variant based on required flash size (e.g., 4MB embedded flash) and antenna integration preference.
precision color sensor
- Need: Accurately measure RGB/XYZ tristimulus values matching human eye CIE 1931 response under controlled illumination.
- Class: Digital color sensor (XYZ or RGB true-color filter array) with I2C interface and IR blocking filter
- Shortlist: ams OSRAM TCS34725, Texas Instruments OPT4048
- Pick: Select based on spectral responsivity matching CIE 1931 curve, dark current performance, and package size constraints for the wand nozzle.
Li-ion battery charger and DC-DC regulator
- Need: Safely charge single-cell Li-ion battery from USB Type-C and supply a stable, low-noise 3.3V rail for optical sensing and RF transmission.
- Class: Linear Li-ion charge management controller combined with a high-efficiency synchronous step-down DC-DC converter
- Shortlist: Microchip MCP73831 + TI TPS62180, Analog Devices LTC4054 + TPS62840
- Pick: Select based on quiescent current, charging current requirements (e.g., 500mA), and ultra-low noise performance to avoid corrupting optical analog front-ends.
Risk register
| ID | Area | Severity | Detail | Mitigation |
|---|---|---|---|---|
| r1 | thermal | med | High-CRI LED illumination generates localized heat near the optical sensor inside the enclosed wand tip, causing thermal drift in color measurements. | Pulse the LED illumination only during active measurement windows (fraction of a second) and implement software temperature compensation using an on-board thermistor or sensor internal temp reading. |
| r2 | emi | high | ESP32-C3 Wi-Fi/BLE radio transmissions can inject high-frequency noise into the sensitive color sensor's I2C lines or the analog power supply rail, causing measurement jitter. | Use a dedicated LDO or heavily filtered DC-DC rail for the OPTICAL_SENSING module, place physical ground shielding between the RF section and the optical frontend, and route I2C traces away from the antenna. |
| r3 | mech | high | The 45°/0° optical geometry required for accurate colorimetry depends entirely on rigid mechanical alignment of the LED, sensor, and optical aperture; any drop or flex will ruin calibration. | Design an internal rigid structural chassis (e.g., black anodized aluminum or glass-filled PBT bracket) to lock the optical components in place, independent of the outer cosmetic wand shell. |
Bring-up and Validation Plan
- Power-off inspection and rail resistance checks
- Current-limited first power-up; verify every rail before enabling loads
- Validate interfaces and timing one subsystem at a time
- Run thermal, fault-injection, EMC pre-scan, and endurance tests for the target environment
Key Components
4/4 modules matched to real parts. See the BOM tab for the full component table.
Texas Instruments TPS62180 or MCP73831 Linear Li-Ion Charger with USB-C (MCP73831)
Candidate 2 is the exact base MPN for the MCP73831 linear Li-Ion charger from Microchip, matching the primary MPN and pr
Espressif ESP32-C3 Single-Core Wi-Fi & BLE 5 SoC (ESP32-C3-MINI-1-N4)
The candidate 'ESP32-C3' matches the primary MPN exactly.
Build Summary
- Difficulty: Intermediate
- Estimated time: 3-5 hours
- Tools required: Antistatic tweezers, Digital microscope, ESD mat, Compressed air can, Lint-free isopropyl alcohol wipes, Temperature-controlled soldering iron
See the Build tab for the full step-by-step assembly guide.
Evidence and Limitations
- Confirm part parameters, certifications, and compatibility against current manufacturer documents.
- Treat industry compliance without test or certificate evidence as a compliance gap, not an approval.
- See Reference Images for visual artifacts and Build Guide for detailed assembly and bring-up steps.