16-channel digital input module based on MCP23017

What is it?

This is a 16-channel industrial digital input module designed for 24VDC systems, based on the MCP23017 I2C GPIO expander.

Unlike typical low-voltage GPIO boards, this module is built for real-world applications, allowing you to directly interface with 24V sensors, switches, and control signals.

Each input is opto-isolated and conditioned, providing reliable and noise-resistant signal acquisition for embedded systems and industrial control panels.

Why this board is different

Most I2C GPIO expanders: - Operate at 3.3V / 5V only - Require external signal conditioning - Are not suitable for industrial environments

This board solves that by providing: - Direct 24VDC input compatibility (PNP / sourcing signals) - Opto-isolation between field and logic - Integrated protection (TVS, reverse polarity) - Per-channel filtering for noise reduction

This allows direct connection to real industrial signals without additional interface circuits.

Key Features - 16 × 24VDC digital inputs (PNP / sourcing) - Opto-isolated inputs (field side isolated from logic side) - MCP23017 I2C interface (3.3V logic) - On-board 24V → 3.3V regulator - Per-channel input protection and filtering - TVS surge suppression + reverse polarity protection - Interrupt outputs (INTA / INTB) - Reset signal access - Configurable I2C address (up to 8 modules) - I2C IN / OUT connectors for daisy-chaining - Optional onboard I2C pull-ups

Electrical Characteristics - Input voltage: 24VDC nominal - Input type: PNP (sourcing) - Detection levels: - ON ≥ 12V (recommended) - OFF ≤ 5V - Input current: ~6.8 mA per channel @ 24V - Logic interface: I2C (3.3V)

Typical Applications - PLC and embedded controller input expansion - 24V sensor interfacing (proximity sensors, limit switches, etc.) - Industrial control panels - Alarm and status monitoring systems - Remote / distributed I/O systems

Integration - Connect 24V signals directly to input terminals - Communicate via I2C - Daisy-chain multiple modules (up to 8 boards)

Designed to work seamlessly with STM32, ESP32, and other microcontrollers.

Important Notes - Designed for 24VDC industrial systems only - Inputs are PNP (sourcing type) - Field side is opto-isolated from logic side - Do not exceed intended input voltage levels - Power down before wiring changes

Learn more:
🌐 www.eacontroltech.com