TI中文支持网假设设定PWM1与PWM4同步，PWM4发出同步信号，PWM1接受同步信号。另外PWM1在计数器为零时将触发一个事件。
如果PWM1比4计数快，那么PWM1计数器首先归零触发事件，而PWM4稍后归零。然而，PWM4归零时将产生同步信号使得PWM1再次归零，那么是不是会再一次触发PWM1的事件？如何解决这个问题？
还有一个附带的问题，在PWM周期寄存器设定为映射模式时，如何判断映射寄存器的值是否已经载入过周期寄存器中，从而可以将其覆盖？
Seven Han：2.2.3.3 Time-Base Counter Synchronization
A time-base synchronization scheme connects all of the ePWM modules on a device. Each ePWM
module has a synchronization input (EPWMxSYNCI) and a synchronization output (EPWMxSYNCO). The
input synchronization for the first instance (ePWM1) comes from an external pin. The possible
synchronization connections for the remaining ePWM modules are shown in Figure 7, Figure 8, and
Figure 9.
www.ti.com/…/sprug04a.pdf
