In the suspend state, an H/PC uses minimal power to maintain its clock, its applications, and the persistent data stored in RAM. To reduce power requirements, an H/PC removes power from unneeded circuits and devices, such as the keyboard decoder, display, scratch-pad memory, and processor. A PC Card storage device driver determines the power that it uses when the device is in the suspend state. The processor might take as long as 100 milliseconds to wake up from this state.
An H/PC switches to the suspend state when the following events occur:
Windows CE uses an activity timer to gauge whether a user is actively using a device. The timer counts down while the device is in the on state. When the timer reaches zero, the H/PC switches to the suspend state. The user can set the maximum value of this timer, in seconds. Two events reset the timer to its maximum value: a key press or release or a touch event. When the timer reaches five seconds, the H/PC sounds a warning to alert the user that it is about to suspend operation. The operating system does not notify applications when it enters the suspend state because most applications are not affected by this transition. When the device resumes operation, applications also resume operation as if they had been continuously running.