几个专有名词
System OFF mode：
System ON mode：
Sub power modes：
- Constant latency
- Low power
功能模块（CPU、外设等）的两个模式
IDLE mode：挂起
RUN mode：运行 每一个内存Section都可以单独配置进入System OFF后是否保存数据，可以保存大量数据，甚至RTOS的上下文 ：-）
Sub power模式下PPI都是正常工作的， System OFF mode is deepest power saving mode the system can enter.In this mode, the system’s corefunctionality is powered down and all ongoing tasks are terminated.
最节能的模式，核心被关闭，所有任务被终止。 System ON is the default state after power-on reset. In System ON, all functional blocks such as the CPU orperipherals, can be in IDLE or RUN mode, depending on the configuration set by the software and the state of the application executing.
复位后的运行模式，所有的能模块（CPU、外设等）都可以配置为挂起、运行。 In constant latency mode the CPU wakeup latency and the PPI task response will be constant and kept at a minimum. This is secured by forcing a set of base resources on while in sleep. The advantage of having a constant and predictable latency will be at the cost of having increased power consumption. The constant latency mode is selected by triggering the CONSTLAT task. In low power mode the automatic power management system, described in System ON mode on page 80, ensures the most efficient supply option is chosen to save the most power. The advantage of having the lowest power possible will be at the cost of having varying CPU wakeup latency and PPI task response. The low power mode is selected by triggering the LOWPWR task.