This is a rundown on how the system will act. Documentation on the protocol and configuration data shows what can be done in greater detail.
Power Control: Operation
- Initial power up
On power up, the system cutts power to the computer and reads the settings, such as temperature and voltage thresholds, from EEPROM. The flag indicating if the computer's power was applied when running power was last applied is set to indicate the computer was not supplied with power (this isn't kept in EEPROM).
- Running power applied
- When the running power is initially applied, power to the computer will be applied after a few seconds if:
During such a wait, the user indicator will flash. If any of the conditions are not met, no attempt will be made to apply power until the user requests it.
- the computer was running when the running power was last lost
- the enviornmental conditions are within the thresholds allowing application of power
- the user does not press the input button
- While running power is applied, the user may request power to the computer be applied or cut. To do this:
- the user presses the input button to toggle power to the computer
- the user turns on or off the stereo (external device) -- note how this doesn't affect operation when running power is initially applied. It only affects operation after that.
- To apply power:
- The enviornmental conditions must be within the thresholds allowing application of power. Otherwise, the request will be ignored.
- The relay that supplies power to the computer will be switched to apply power
- To cut power:
- The computer is informed of a shutdown request after the user request
- The computer requests a shutdown and supplies a delay time to loss of power
- Any further shutdown requests by the computer will update the delay time
- If the computer does not issue a shutdown abort command, the relay that supplies power to the computer will be switched to cut power after the delay time has elapsed
- If the environment leaves one or more thresholds
- The computer is informed of an impending forced shutdown and told the amount of time it has before loss of power
- The computer may request one extension of time on the shutdown up to the length of time initially granted for time until power loss
- The computer cannot abort the shutdown
- After the time has elapsed, the relay that supplies power to the computer will be switched to cut power
- Running power lost
- The computer is still running
- The system notes that the computer was still running at loss of running power
- The computer is told that running power is lost, but is allowed to run until the environment is beyond a threshold
- The system can be configured to force a shutdown upon loss of running power
- The computer is not running
- The user may or may not be able to apply power depending on the configuration.