Abstract: A system comprising a real time clock, RTC, and a processor configured to execute a secure application to provide a secure clock and configured to operate in a first low-power-mode and a first normal-mode, and a non-secure application configured to perform a clock modification procedure and configured to operate in a second low-power-mode and a second normal-mode, the system configured to perform a secure clock initialisation procedure comprising obtaining a record of a current time from the RTC based on a transition from the first low-power-mode to the first normal-mode, wherein the secure application is configured to perform a clock update procedure including updating the RTC with a secure record of the current time and wherein the system is further configured to prevent performing the clock modification procedure after the clock update procedure has been performed.

Abstract: Power management circuitry includes a power management circuitry having a handshake watchdog (HWD) timer and configured to, upon a reset, set the HWD timer to a maximum delay time allowed between an initial wakeup request received at a first input and a qualified wakeup request expected at a second input and configured to start the HWD timer counting in response to the initial wakeup request. Processing circuitry includes a wakeup signal aggregator configured to receive wakeup signals from internal and external wakeup events and to provide a notification of an occurrence of a wakeup event. The notification is provided as the initial wakeup request. A low power mode sequencer configured to initiate a low power mode exit sequence in response to the notification from the wakeup signal aggregator and to provide the qualified wakeup request as a result of performing at least a portion of the exit sequence.

Abstract: A method and apparatus for storing and classifying packets transmitted over a network to a processor in a low power mode. The processor receives and classifies the packets as interesting or not interesting. Uninteresting packets are discarded while interesting packets are stored in memory. For the first interesting packet received, a receive timer is activated and for every interesting packet received a counter is incremented. A transmit timer is activated when the processor enters the low power mode. When either the receive timer expires, the transmit timer expires or the counter reaches a threshold value then a wake-up interrupt is asserted.

Abstract: A method and apparatus for storing and classifying packets transmitted over a network to a processor in a low power mode. The processor receives and classifies the packets as interesting or not interesting. Uninteresting packets are discarded while interesting packets are stored in memory. For the first interesting packet received, a receive timer is activated and for every interesting packet received a counter is incremented. A transmit timer is activated when the processor enters the low power mode. When either the receive timer expires, the transmit timer expires or the counter reaches a threshold value then a wake-up interrupt is asserted.