4571 Datasheet, PDF (46/126 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4571 Group
(Note 1)
Reset
State A
Operating state
f(XIN) : operating
POF instruction execution
(Note 2)
Key-on wakeup
(Notes 1, 3)
State D
RAM back-up mode
f(XIN) : Stop
Notes 1: Microcomputer starts its operation after counting f( XIN) 5400 to 5424 times from system is released from reset.
2: Continuous execution of the EPOF instruction and the POF instruction is required to go into the RAM back-up state.
3: The operation mode also returns to the initial state (internal frequency divided by 4 mode) (register MR initialized).
Fig 47. State transition
EPOF
POF
instruction ⁺ instruction
Power down flag (P)
SQ
Internal reset signal
R
- Set source ... _{EPOF instruction + POF instruction}
- Clear source ... Reset
Fig 48. Set source and clear source of the P flag
Software start
SNZP instruction
P = “1”
Yes
?
No
Cold start
Warm start
Fig 49. Start condition identified example using the
SNZP instruction
Rev.1.02 May 25, 2007 Page 46 of 124
REJ03B0179-0102