IBM PPC440X5 Manual de usuario descargar pdf (Pagina 209)

100

101

User’s Manual

Preliminary PPC440x5 CPU Core

timers.fm.

September 12, 2002

Page 209 of 589

7. Timer Facilities

The PPC440x5 provides four timer facilities: a time base, a Decrementer (DEC), a Fixed Interval Timer (FIT),

and a Watchdog Timer. These facilities, which share the same source clock frequency, can support:

• Time-of-day functions

• General software timing functions

• Peripherals requiring periodic service

• General system maintenance

• System error recoverability

Figure 7-1 shows the relationship between these facilities and the clock source.

7.1 Time Base

The time base is a 64-bit register which increments once during each period of the source clock, and provides

a time reference. Access to the time base is via two Special Purpose Registers (SPRs). The Time Base

Upper (TBU) SPR contains the high-order 32 bits of the time base, while the Time Base Lower (TBL) SPR

contains the low-order 32 bits.

TBL (32 bits)

TBU

clocks)

TBL

clocks)

TBL

clocks)

TBL

clocks)

TBL

clocks)

TBL

clocks)

TBL

clocks)

TBL

clocks)

Watchdog Timer

Fixed Interval Timer

Time Base (Incrementer)

TBU (32 bits)

DEC (Decrementer)

(32 bits)

Zero Detect Decrementer exception

Figure 7-1. Relationship of Timer Facilities to the Time Base

Reference

Clock

Source

Period

1 2 ... 204 205 206 207 208 209 210 211 212 213 214 ... 589 590

Comentarios a estos manuales

Sin comentarios

IBM PPC440X5 Manual de usuario Pagina 209

Comentarios a estos manuales

Relacionado con productos y manuales para Procesadores IBM PPC440X5