The trick to conserving power is to do nothing—or next to nothing. Most low-power microcontrollers utilize this approach in some fashion. Freescale’s MPC8536E incorporates a number of features to optimize power consumption in a network environment. Its gigabit Ethernet ports support packet lossless deep sleep. When in use, the Ethernet ports are active and filter incoming network traffic while the rest of the chip is in deep-sleep mode. Packets are buffered in local memory and copied to dynamic memory if they’re destined for processing based on the advanced filtering system. The 1.5-GHz e500 processor is then started. The MPC8663E also has a range of lower-power jog modes including doze (snooping on), nap (processor idle), sleep (CPU and snoop off), and deep sleep, which uses less than 1 W. The Ethernet filtering support can operate in all these modes.
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