2.4.3. Event communication using WFE or SEV

An external agent can use the the EVENTI pin to participate in a WFE or SEV event communication of the Cortex-A7 MPCore processor. When this pin is asserted, it sends an event message to all the Cortex-A7 MPCore processors in the cluster. This is similar to executing a SEV instruction on one processor in the cluster. This enables the external agent to signal to the processors that it has released a semaphore and that the processors can leave the WFE standby power saving mode. The EVENTI input pin must remain HIGH at least one CLK clock cycle to be visible by the processors.

The external agent can determine that at least one of the Cortex-A7 MPCore processors in the cluster has executed an SEV instruction by checking the EVENTO pin. When SEV is executed by any of the processors in the cluster, an event is signaled to all the processors in the cluster, and the EVENTO pin is asserted. This pin is asserted HIGH for one CLK clock cycle when any Cortex-A7 MPCore processor in the cluster executes an SEV instruction.

Copyright © 2011-2013 ARM. All rights reserved.ARM DDI 0464F