PCA9555，NXP的I2C接口16位GPIO扩展芯片，可读可写，针对一般中低速应用I/O扩展，扩展简单，应用方便；(PCA9555, NXP I2C interface, 16 bit GPIO expansion chip, readable and writable, for the general medium and low speed applications I/O expansion, expansion simple, easy to use;)