4518 Datasheet, PDF (64/160 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4518 Group
Reset
A
Operation state
• Operation source clock:
(Note 1) _f(RING)
• f(XIN): Stop
(Note 2) MR1←0
MR1←1
(Note 5)
Key-on wakeup
E
RAM back-up mode
POF instruction
execution
(Note 4)
B
Operation state
• Operation source clock:
f(RING)
• f(XIN): Operating
(Note 3) MR0←0
MR0←1
POF instruction
execution
(Note 4)
C
Operation state
• Operation source clock:
f(XIN)
• f(RING): Operating
RG0←1
RG0←0
POF instruction
execution
(Note 4)
D
Operation state
• Operation source clock:
f(XIN)
• f(RING): Stop
POF instruction
execution
(Note 4)
f(RING): stop
f(XIN): stop
Notes 1: Microcomputer starts its operation after counting f(RING) 120 to 144 times.
2: The f(XIN) oscillation circuit (ceramic resonance, RC oscillation or quartz-crystal oscillation) selected by the CMCK, CRCK or CYCK
instruction starts oscillatng (the start of oscillation and the operation source clock is not switched by these instructions).
The start/stop of oscillation and the operation source is switched by register MR.
Surely, select the f(XIN) oscillation circuit by executing the CMCK, CRCK or CYCK instruction before clearing MR1 to “0”.
MR1 cannot be cleared to “0” when the oscillation circuit is not selected.
3: Generate the wait time by software until the oscillation is stabilized, and then, switch the system clock.
4: Continuous execution of the EPOF instruction and the POF instruction is required to go into the RAM back-up state.
5: System returns to state A certainly when returning from the RAM back-up mode.
However, the selected contents (CMCK, CRCK, CYCK instruction execution state) of f(XIN) oscillation circuit is retained.
Fig. 53 State transition
EPOF
POF
instruction + instruction
Power down flag P
SQ
Reset input
R
q Set source ^{• • • • • • •} _{EPOF instruction +} POF instruction
q Clear source ^{• • • • • •}Reset input
Fig. 54 Set source and clear source of the P flag
Rev.3.01 2005.06.15 page 64 of 157
REJ03B0008-0301
Program start
Yes
P = “1”
?
No
Cold start
Warm start
Fig. 55 Start condition identified example using the SNZP in-
struction