Fujitsu FR30 Computer Hardware User Manual


 
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3.10 Standby Mode (Low Power Consumption Mechanism)
[Example of setting the maximum gear speed:]
Returning from the Stop State
An interrupt or resetting can be used to return from the stop state.
Return by way of an interrupt
When the interrupt enable bit, which is one of the peripheral functions, is on, a peripheral
interrupt can be caused to return from the stop state.
The procedure for returning from the stop state to the normal run state is as follows:
Interrupt generation --> restart of oscillation circuit operation --> wait for oscillation
stabilization --> restart of internal peripheral clock supply after stabilization --> restart of
internal DMA clock supply --> restart of internal bus clock supply --> restart of internal
CPU clock supply
Program execution after the oscillation stabilization wait time is as follows:
When the level of the interrupt is enabled by the I flag of CPU ILM
The program saves the register, fetches the interrupt vector, and executes processing
beginning from the interrupt processing routine.
When the level of the interrupt is disabled by the I flag of CPU ILM
The program executes instructions beginning from the instruction following the instruction
that caused the transition to the stop state.
Return by way of the RSTX pin
The procedure for returning from the stop state to the normal run state is as follows:
LDI:20 #GCR,R0
LDI:8 #00000011b,R1 ; CHC = 1, CPU = Peripheral gear
ratio
STB R1,@R0 ; DBLON=0
loop
BTSTH #0010b,@R0 ;
BNE loop ; Wait until DBLAK becomes 0
LDI:20 #STCR,R0
LDI:8 #10010000b,R1 ; STOP=1
STB R1@R0
NOP ;
NOP ;
NOP ;
NOP ;
NOP ;
NOP ;