PCA捕捉模块0的CEX0被设置在按键S3对应的引脚上，按下和松开S3，将会产生下降和上升沿信号，引发捕捉模块动作。-PCA Capture Module CEX0 0 is set on the keys S3 corresponding pin, press and release S3, it will have a fall and rising signal, triggering capture module operation.