Design of Portable PPG Heart Rate Detection System Based on Single Chip Microcomputer

Abstract

Reliable pulse wave acquisition and heart rate tracking are critical to the evolution of portable pulse diagnosis tools, especially for point-of-care and daily monitoring scenarios. Existing acquisition modules frequently impose a trade-off: analog-intensive front ends hinder miniaturization and increase power draw, whereas more compact, fixed-function designs often foreclose the later addition of complementary sensing modalities such as pressure-based metronome. This study introduces an STM32-based photoplethysmographic (PPG) heart rate detection system built around a fully integrated optical sensor. Pulse waveform data are converted to the digital domain on sensor and streamed directly to the micro-controller via an I²C link, with heart rate values refreshed in real time on an OLED display. The architecture addresses prior limitations in two concrete ways. First, the all‑digital signal chain eliminates the need for discrete analog conditioning components, yielding a significantly smaller footprint and lower cost without compromising waveform fidelity. Second, the board incorporates a reserved signal‑conditioning path centered on an operational amplifier, which provides the necessary gain and band-limiting for future pressure‑pulse sensors. This deliberate provision preserves both the portability of the current unit and the flexibility required for subsequent hardware expansions, effectively decoupling core functionality from peripheral augmentation. The paper details the hardware design rationale and confirms operational integrity of the principal modules through empirical testing. The resulting platform constitutes a low-cost, lightweight front-end solution that directly supports the iterative development and refinement of new‑generation pulse diagnostic instruments.