Rainbow Electronics AT89C5131 User Manual
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146
AT89C5131
4136A–USB–03/03
Figure 65. Power-down Exit Waveform
Exit from power-down by reset redefines all the SFRs, exit from power-down by external
interrupt does no affect the SFRs.
Exit from power-down by either reset or external interrupt does not affect the internal
RAM content.
Note:
If idle mode is activated with power-down mode (IDL and PD bits set), the exit sequence
is unchanged, when execution is vectored to interrupt, PD and IDL bits are cleared and
idle mode is not entered.
This table shows the state of ports during idle and power-down modes.
Note:
1. Port 0 can force a 0 level. A “one” will leave port floating.
INT1
INT0
XTALA
Power-down Phase
Oscillator restart Phase
Active Phase
Active Phase
or
XTALB
Table 98. State of Ports
Mode
Program
Memory
ALE
PSEN
PORT0
PORT1
PORT2
PORT3
PORTI2
Idle
Internal
1
1
Port
Data
(1)
Port
Data
Port Data
Port Data
Port
Data
Idle
External
1
1
Floating
Port
Data
Address
Port Data
Port
Data
Power-down
Internal
0
0
Port
Data
(1)
Port
Data
Port Data
Port Data
Port
Data
Power-down
External
0
0
Floating
Port
Data
Port Data
Port Data
Port
Data