## 3 Processing Method of Vibration Piezoelectric Signal
### The Schematic of Piezoelectric Detection Device  
The electronic circuit schematic of the chip-based vibration piezoelectric detection device is illustrated in Figure 5.  
We further describe the relevant chip electronic circuit principle as well as the technical parameters. The pin definitions are provided in Table 2. The technical parameter list is shown in Table 3.  
Figure 5: Electronic circuit diagram of vibration piezoelectric detection device based on chip.  
In this study, wireless communication technology was integrated into a vibration-assisted crop seed drying tray system to enable the real-time monitoring of seed moisture variation and the overall drying process. The specific implementation strategies are detailed as follows:  
1. Integration of Sensors and Wireless Modules:  
Piezoelectric sensors were embedded within the vibrating plate to detect collision signals resulting from interactions between seeds and the tray as well as to monitor the dynamic motion of the seeds. The acquired signals are transmitted wirelessly to a receiver via an embedded communication module, enabling real-time tracking of the drying process.
2. Real-Time Data Transmission:  
The wireless communication module facilitates the real-time transfer of time-domain response signals--such as seed collisions and moisture variation--captured by the piezoelectric sensors to the processing unit. This capability allows the system to dynamically adjust operational parameters, thereby optimizing drying performance based on real-time feedback.  
The complete workflow of the wireless communication subsystem is as follows. The piezoelectric sensor detects collision events between seeds and the tray surface. These raw signals are conditioned through an amplification and filtering circuit to enhance signal quality. The shortest routing protocol (SRP) is employed to mitigate discontinuous interference in the communication link, thereby improving transmission reliability. A microcontroller unit (STM32) acquires the conditioned analog signal via an analog-to-digital converter (ADC) and performs preliminary signal processing. The processed data are then transmitted to a cloud platform (Ali IoT) via a wireless module (Wi-Fi). On the cloud platform, the data are stored and subsequently analyzed using MATLAB 2020, where advanced signal processing algorithms extract key features such as collision frequency and amplitude. These features are then used to assess the drying status of the crop seeds.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Serial Number** & **Pin Definition** & **Function Description** & **Remark** \\ \hline
1 & VCC & Module power positive & 5 V power supply \\
2 & GND & Module power negative & When there is no vibration, the output voltage signal is about 2 V, and when there is vibration, the output voltage signal fluctuates up and down based on the 2 V level. The greater the vibration amplitude, the greater the voltage value. \\
4 & DO & TTL level output interface & The comparison voltage value is 0.5 VCC; the output is low when the comparison voltage is greater than the voltage, and the output is high when the comparison voltage is smaller \\
5 & +/ – & Piezoelectric thin film & Do not distinguish between positive and \\  & & sensor interface & negative poles \\ \hline \hline \end{tabular}
\end{table}
Table 2: Pin definitions.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Index** \\ \hline Operating voltage & 5 V \\ AO Output voltage range & 0.7–4.3 V \\ Magnification adjustment range & 0–100 \\ Size (length) & 38 \(\times\) 14.5 mm \\ \hline \hline \end{tabular}
\end{table}
Table 3: Technical parameter list.  
The wireless communication module also facilitates the real-time monitoring of the equipment's operational status by providing continuous feedback on parameters such as vibration frequency and airflow velocity. This functionality aids in the early detection of mechanical faults and supports timely maintenance, thereby ensuring uninterrupted and stable operation of the drying system.