What is it?

This is a 4-channel software-configurable industrial analog I/O module, based on the Analog Devices AD74412R.

Each channel can be independently configured via software to operate as:

• Voltage Input (0–10V)
• Current Input (0–25mA / 4–20mA)
• Voltage Output (0–11V)
• Current Output (0–25mA)
• RTD Input (PT100 / PT1000, 2-wire)

The board is designed for 24V industrial systems and integrates full signal conditioning, protection, and power regulation, enabling direct connection to real-world field signals.

Communication is handled via a simple SPI interface, making it easy to integrate with STM32, ESP32, and other embedded controllers.

Why this board exists

Building a flexible industrial analog I/O system typically requires:

• Separate input and output circuits
• Signal conditioning and protection design
• Careful handling of 24V field signals
• Significant hardware and firmware effort

Most available solutions are:

Fixed-function (input or output only), or Expensive modular systems not suited for embedded integration

This board provides a compact, deployment-ready analog front-end, allowing engineers to integrate advanced analog I/O functionality without redesigning complex circuitry.

What makes it different

True software-defined I/O (per channel) Each channel can be dynamically configured as voltage, current, or RTD input/output. A single board can replace multiple dedicated modules.

Industrial-ready design (24V systems) Designed for direct integration into 24V environments with proper power architecture, protection, and field wiring support.

Integrated analog front-end (AD74412R) Combines multiple precision analog functions into a single platform, reducing design complexity and improving reliability

Wide signal compatibility Supports standard industrial ranges (0–10V, 4–20mA, RTD) without requiring external signal conditioning.

Compact and scalable architecture Small form factor with SPI daisy-chain capability for multi-board expansion.

Key Features

• 4 independently configurable analog I/O channels
• Voltage input: 0–10V
• Current input: 0–25mA (supports 4–20mA)
• Voltage output: 0–11V
• Current output: 0–25mA
• RTD support: PT100 / PT1000 (2-wire)
• SPI communication interface (3.3V logic)
• 24VDC industrial power input
• On-board 3.3V and analog supply regulation
• Reverse polarity protection + TVS surge suppression
• Hardware address / chip-select configuration
• Auxiliary signals: RESET, ALERT, ADC_READY

Typical Applications

• Industrial control and automation systems
• PLC / RTU development and expansion
• Process control (temperature, pressure, flow)
• Sensor and actuator interfacing
• Test and measurement platforms
• Rapid prototyping of industrial analog systems

Integration

• Connect directly to a microcontroller via SPI
• Configure each channel via software
• Support for multi-board expansion using shared SPI bus

Designed for seamless integration with STM32, ESP32, and similar platforms.

Important Notes

• Designed for 24VDC industrial systems
• Non-isolated design (shared system ground)
• All channels share a common ground reference
• Ensure proper grounding practices in your system
• Do not exceed signal limits for the selected mode
• Power down before modifying wiring