Power Management Modes on the ARM11 Processors

 

Run Mode

 

 

This mode is the normal mode of operation in which all of the functionality of the ARM11 processor is available.

 

 

Standby Mode

 

 

This mode disables most of the clocks of the device, while keeping the device powered up. 

Enter into Standby Mode through  a Wait For Interrupt instruction.

 

Return to Run Mode by:

• an interrupt (nIRQ) or fast interrupt (nFIQ), whether masked or unmasked

• an external debug request (EDBGRQ), regardless of whether debug is enabled

• assertion of Reset.

 

 

Shutdown Mode

 

 

This mode allows the entire device to power down.

All processor state, including cache and TCM state, must be saved externally.

Enter Standby Mode by executing a Wait For Interrupt instruction. The core then asserts the STANDBYWFI signal to indicate to the external power controller that the processor is in Standby Mode and is ready to be powered down to enter Shutdown Mode.

 

 

Implementation of Shutdown Mode also requires the following external considerations:

• Implementation of an external Power Management Controller to control the power supply and reset signals for the core, and that can differentiate between an initial Power On Reset and subsequent returns from Dormant or Shutdown Mode.

• The part must be returned to Run Mode by the assertion of Reset.

 

 

Dormant Mode

 

 

 

This mode enables the ARM11 processor core to power down while leaving the caches and the TCM powered up and maintaining their state. Similar to Shutdown Mode, all state must be saved, with the exception of the contents of the caches and the TCMs.

 

Dormant mode is partially supported on ARM1136JF-S processors.