Warm Reset Flow

Figure 7–3 Sleep Mode Sequence of Operation

internal clks

state

SLEEP IPR Wake-up interrupt

SromOE_L

ClkFwdRst_H

TestStat_H

 

 

 

 

 

 

b

 

f

 

RUN

DOWN1

DOWN2

DOWN3 WAIT_INTR

RAMP1

RAMP2

WAIT_ClkFwdRst0

 

WAIT_BiSI WAIT_ClkFwdRst1

RUN

 

 

 

 

 

 

a

c

e

 

 

 

 

 

 

 

 

 

 

no min

no min

A

d

internal ClkFwdRst

external Clks

FM-06487A.AI4

Table 7–7describes each signal and constraint for the sleep mode sequence.

Table 7–7 Signals and Constraints for the Sleep Mode Sequence

Signal Name

Description

Constraint

 

 

 

ClkFwdRst_H

Signal asserted by the system to

 

initialize and reset clock forwarding

 

interfaces

Forwarded clocks

Bit clocks forwarded to/from the

 

21264/EV68A

System interrupt

Asynchronous interrupt which

 

causes the 21264/EV68A to exit

 

sleep mode

ClkFwdRst_H must be asserted by the system when entering sleep mode. The system deasserts ClkFwdRst_H no sooner than one FrameClk_H cycle after sourcing an interrupt to the 21264/ EV68A.

Clocks stop running under ClkFwdRst_H.

7.4 Warm Reset Flow

The warm reset sequence of operation is triggered by the assertion of the Reset_L sig- nal line. The reset state machine is initially in RUN state. The 21264/EV68A then, by default, ramps down the PLL (similar to the sleep flow sequence) and the reset state machine ends up in the WAIT_RESET state.

Note the effects of entry into that state on the IPRs listed in Table 7–8 .

Table 7–8 Effect on IPRs After Warm Reset

IPR

Effects After Warm Reset

 

 

PAL_BASE Cleared

I_CTLCleared

PCTX[FPE] Set

WRITE_MANY Cleared (That is, the WRITE_MANY chain is initialized and the Bcache is turned off.)

21264/EV68A Hardware Reference Manual

Initialization and Configuration 7–11

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Compaq EV68A Warm Reset Flow, Signals and Constraints for the Sleep Mode Sequence, Effect on IPRs After Warm Reset