NXP Semiconductors MPC5644A Reference Manual

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NXP Semiconductors MPC5644A Reference Manual Manual pdf 746 page image

Enhanced Time Processing Unit (eTPU2)MPC5644A Microcontroller Reference Manual, Rev. 6746 Freescale SemiconductoreTPU provides higher resolution than the Host CPU can achieve and creates no Host overhead forservicing timing tasks.Latency is the interval from occurrence of an event to the start of event servicing. eTPU can service itsown events without interrupting the Host. There are two types of timing events:• Input pin transition• Selected Time Base match, that is, a selected Time Base counter reached or exceeded apreprogrammed valueService time is the time spent servicing an event. In general, in microcontrollers the service time isconstrained because the instruction set is not optimized for time function synthesis. The eTPU instructionset is optimized, so that time functions can be implemented with much fewer instructions than the HostCPU. Instructions execute faster, service time is reduced and program memory compacted.Instructions executed by the eTPU are connected directly to the eTPU timing hardware and allowparallelism of hardware related actions.24.2.1 OverviewFigure 24-1 shows a top-level eTPU block diagram.