CHAPTER 3: CPU OPERATION

During SLEEP status, as in the HALT status, the contents of the registers in the CPU that have been set before shifting are maintained if rated voltage is supplied.

Figure 3.6.2.1 shows the sequence of shifting to the SLEEP status and restarting.

When an interrupt that releases the SLEEP status is generated, the oscillation circuit begins to oscillate. When the oscillation starts, the CLK input to the CPU is masked by the peripheral circuit and the input to the CPU begins after stabilization waiting time (several 10 msec–several msec) has elapsed. The CPU samples the interrupt at the falling edge of the initially input CLK and starts the interrupt processing.

OSC

 

T1 T2 T3 T4

 

T1T2 T3 T4

CLK

 

 

 

PK

 

 

 

PL

 

 

 

PC

pc

pc+1

 

FETCH

SLP

 

DUMMY

DBS1/0

ANY

0

2

STOP

 

 

 

IRQ

 

 

 

 

 

Oscillation stable

 

 

 

waiting time

 

 

 

SLEEP status

Interrupt processing

Fig. 3.6.2.1 Sequence of the shift to SLEEP status and restarting

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EPSON

S1C63000 CORE CPU MANUAL