esp-now-differential-probe

Industrial measurement platform combining ESP-NOW sensor nodes and a W5500 Ethernet gateway with 16-channel ADC, FreeRTOS, and custom PCB.

COMPONENTS Hardware components

WIZnet - W5500

x 1

PROJECT DESCRIPTION

Why This Project Stands Out

Many embedded measurement systems stop at data acquisition. This project goes significantly further.

It combines:

Distributed wireless measurement nodes using ESP-NOW
Local high-resolution 16-channel ADC acquisition
FreeRTOS-based concurrent task execution
Ethernet-based industrial data delivery
Custom-designed hardware including PCB, Ethernet interface, and analog front-end
Python-based capture and visualization tools

The result is not simply a sensor node connected to a network.

It is a complete measurement infrastructure designed from the PCB level through to data analysis software.

System Architecture

Generated By GPT

Hybrid Network Concept

The project deliberately separates networking responsibilities.

Wireless Edge Layer

Distributed measurement probes
Reduced field wiring
Easier installation across large physical areas
Low-latency ESP-NOW communication

Wired Backhaul Layer

Reliable Ethernet transport
Deterministic communication path
Stable long-duration acquisition
Simplified integration with servers and SCADA systems

This hybrid architecture directly addresses one of the most common industrial deployment problems: balancing installation flexibility with network reliability.

Where WIZnet Fits

The W5500 is not used as an external shield or evaluation module.

Instead, it is integrated directly into the custom hardware design as a native system component.

Hardware-Level Integration

The gateway board incorporates:

W5500 Ethernet controller
RJ45 interface
Dedicated SPI bus
Ethernet link monitoring
Hardware reset circuitry

The design uses the W5500 LQFP-48 device directly on the PCB, making this a true product-level implementation rather than a development-board demonstration.

Hardwired TCP/IP as an Embedded TOE Example

One of the most technically interesting aspects of this project is its use of the W5500 as a practical TCP Offload Engine (TOE).

In conventional embedded Ethernet systems:

MCU
 ├─ ADC Processing
 ├─ Wireless Handling
 ├─ RTOS Tasks
 └─ TCP/IP Stack

The processor must manage networking alongside all application workloads.

In this design:

ESP32-S3
 ├─ ADC Acquisition
 ├─ Calibration
 ├─ ESP-NOW Communication
 ├─ JSON Serialization
 └─ RTOS Scheduling

W5500
 ├─ TCP
 ├─ IP
 ├─ Socket Management
 └─ Ethernet Protocol Handling

The networking workload is offloaded to dedicated silicon.

This allows the ESP32-S3 to focus on measurement and data-processing tasks while the W5500 independently handles Ethernet communication.

For embedded engineers, this represents a real-world example of TOE deployment in a resource-constrained measurement system.

Engineering Complexity

The value of this project is not a single feature but the interaction of multiple subsystems operating simultaneously.

High-Resolution Measurement

LTC2449
16 channels
24-bit delta-sigma conversion
Differential signal acquisition

Real-Time Software Architecture

FreeRTOS multitasking
Independent ADC acquisition tasks
Ethernet server task
Watchdog supervision
Core affinity assignment

Network Aggregation

Local ADC measurements
Remote ESP-NOW measurements
JSON serialization
TCP-based Ethernet serving

All of these functions execute concurrently on the gateway.

This makes the project significantly more sophisticated than typical Arduino Ethernet examples.

Why It Is More Than "Raspberry Pi + USB Dongle"

A common approach to measurement systems is:

ADC → USB → Raspberry Pi

Networking is often added afterward through external adapters.

This project takes a fundamentally different engineering approach.

The Ethernet subsystem is designed into the hardware architecture from the beginning.

The W5500 is:

Included in the schematic
Included in the PCB layout
Assigned a dedicated SPI bus
Integrated with RTOS services
Used as part of the acquisition pipeline

Networking is therefore a first-class system function rather than an afterthought.

That distinction makes this project a valuable engineering reference for developers building industrial gateways, DAQ systems, and edge measurement platforms.

Key Takeaways

Hybrid architecture combining ESP-NOW wireless sensing and Ethernet backhaul
W5500 directly integrated into a custom KiCad PCB
Practical Hardwired TCP/IP and TOE deployment example
16-channel 24-bit measurement subsystem
FreeRTOS multitasking with concurrent acquisition and networking
End-to-end open-source stack from hardware design to analysis software
Strong reference design for industrial measurement gateways and distributed DAQ systems

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