MITSUBISHI MICROCOMPUTERS
4280 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for INFRARED REMOTE CONTROL TRANSMITTERS
(4) Return signal
An external wakeup signal is used to return from the RAM
back-up mode. Table 8 shows the return condition for each
return source.
Table 8 Return source and return condition
Return source
Return condition
Return by an external “H” level Only key-on wakeup function of the port whose pull-down transistor is
input. turned ON is valid.
Remarks
Ports D7, E0, E1
Ports G, E2
Return by an external “H” level Key-on wakeup function is always valid.
input.
(5) Pull-down control register PU0
Set the contents of this register through register A with the
TPU0A instruction.
•
Pull-down control register PU0
Register PU0 controls the ON/OFF of pull-down transistor,
input, key-on wakeup function of ports E0, E1 and D7.
Table 9 Pull-down control register
Pull-down control register PU0
at reset : 0002
at RAM back-up : state retained
W
Pull-down transistor OFF, input circuit OFF, key-on wakeup invalid
Pull-down transistor ON, input circuit ON, key-on wakeup valid
Pull-down transistor OFF, key-on wakeup invalid
Pull-down transistor ON, key-on wakeup valid
0
1
0
1
0
1
Port D7 pull-down control bit
Port E1 pull-down control bit
Port E0 pull-down control bit
PU02
PU01
PU00
Pull-down transistor OFF, key-on wakeup invalid
Pull-down transistor ON, key-on wakeup valid
Note: “W” represents write enabled.
POF instruction
is executed
A
B
f(XIN) stop
(Stabilizing time a )
Reset
f(XIN) oscillation
(RAM back-up
mode)
Return input
(Stabilizing time a )
: Microcomputer starts its operation after f(XIN) is counted to16384 times.
Stabilizing time a
Fig. 21 State transition
Power down flag P
Software start
POF instruction
Reset input
S
Q
Yes
P = “1”
?
R
No
Warm start
Cold start
● Set source
● Clear source
POF instruction is executed
Reset input
Fig. 23 Start condition identified example using the SNZP
instruction
Fig. 22 Set source and clear source of the P flag
MITSUBISHI
ELECTRIC
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MITSUBISHI [ Mitsubishi Group ]
