要了解一款MCU，首先需要知道就是其ROM空间、RAM空间、IO口数量、定时器数量和定时方式、所提供的外围功能模块（Peripheral Circuit）、中断源、工作电压及功耗等等。-For an MCU, you first need to know is its ROM space, RAM space, IO port number, quantity and timing timer mode, the external function modules provided by (Peripheral Circuit), interrupt source, voltage and power consumption, and so on.