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PowerPC decrementer and Real Time Clock questions


Hi

I am hoping someone can help me, I am very confused on how the Decrementer and the Real Time Clock are used.  I have got Redboot running on a MPC5554 which uses the decrementer to create delays. This is good and ok in my mind.  Where the confusion comes in is when the Kernel creates the real time clock.  On the MPC555 processor the role of the decrementer and the RTC have me very confused.    To add to the confusion, the decrementer can generate a exception while the rtc share an interrupt with the rest of the system.   

Does anyone know how these are all interrelated ???, is there a simpler PPC implementation that would be a good model ???

While both the MPC555 & MPC5554 have a decrementer, periodic timer and a watchdog, the MPC5554 does not have a RTC.

Any enlightenment here for a ecos porting newbie ????


Roman F. Rycerz
Engr Section Mgr
Test & Tools
Motorola IESS, ACES, PCSG, PCG

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