An Arduino-compatible library designed to interface the Analog Front End (AFE) AFE4950 — an ultra-compact, high-precision biomedical acquisition IC — with ESP32, nRF52840, and other microcontrollers. This library enables real-time acquisition of ECG (electrocardiogram) and PPG (photoplethysmogram) signals, making it ideal for both research and embedded healthcare applications.

The AFE4950 Module is a specialized board built for biosignal acquisition with:

• High-precision signal chain components
• Electrostatic discharge (ESD) protection
• High-frequency noise filtering (EMI protection)

These features ensure robust, clean signal acquisition and improve overall reliability, even in demanding environments.

While intended for development, the AFE4950 Module is also suitable for integration into production-ready devices.

This version introduces major architectural improvements:

• Structured ring buffer integration: Internally implemented circular buffer for efficient, non-blocking sample storage.
• Modular ISR handling: Optional use of IRAM_ATTR optimized for ESP32.
• Protocol tagging and packetization: Data packets include headers and sample tags (ECG/PPG identifiers).
• Improved object-oriented design: Allows for better encapsulation and portability.

Deprecated: Functions like ready(), getData() and getBytesToSend() have been removed in favor of availableBytes(), readByte(), and readBytes() for a more efficient pull-based interface.

• Simultaneous acquisition of ECG and PPG in a 3:1 pattern (ECG, ECG, PPG...)
• Interrupt-driven FIFO readout and SPI transfer
• Configurable sampling frequency (e.g., 500 Hz ECG / 250 Hz PPG)
• Clean buffer separation between acquisition and transmission
• Platform-compatible with ESP32, nRF52840, and other MCUs

Use Arduino Library Manager to search for AFE4950 and install the latest version.

#include <AFE4950.h>

Follow the pinout diagram to wire up the SPI interface and control lines (RESET, FIFO_RDY).

Examples include:

• RawPacket-ECG-PPG-Streaming.ino: Streams raw 224-byte data packets
• Separated-ECG-PPG-Decoder.ino: Extracts and prints voltage values for each ECG/PPG sample

• Arduino IDE >= 1.8.13 or PlatformIO
• Compatible hardware (ESP32, nRF52840, STM32, etc.)
• AFE4950 Module with SPI wiring and signal interface

• API Reference
• Example Use Cases
• Register Configuration Details

For questions or feedback, contact: jjlondonocarrillo@gmail.com