Related Register; Fig. 2.9.1 Start Condition Identified Example; Table 2.9.2 Return Source And Return Condition; Table 2.9.3 Start Condition Identification - Renesas 4513 User Manual

APPLICATION
2.9 RAM back-up

Table 2.9.2 Return source and return condition

Return source
Return by an external falling
Ports P0, P1
edge input ("H" "L").
Return by an external "H" level
Port P3 /INT0
0
or "L" level input.
The EXF0 flag is not set.
Return by an external "H" level
Port P3 /INT1
1
or "L" level input.
The EXF1 flag is not set.
(2) Start condition identification
When system returns from both RAM back-up mode and reset, software is started from address 0
in page 0.
The start condition (warm start or cold start) can be identified by examining the state of the power
down flag (P) with the SNZP instruction.

Table 2.9.3 Start condition identification

Return condition
External wakeup signal input
Reset

2.9.2 Related register

(1) Key-on wakeup control register K0
Key-on wakeup control register K0 controls key-on wakeup functions of ports P0
Set the contents of this register through register A with the TK0A instruction. The TAK0 instruction
can be used to transfer the contents of register K0 to register A.
Table 2.9.4 shows the key-on wakeup control register K0.

Table 2.9.4 Key-on wakeup control register K0

Key-on wakeup control register K0
Pins P1 and P1
2
K0
3
control bit
Pins P1 and P1
0
K0
2
control bit
Pins P0 and P0
2
K0
1
control bit
Pins P0 and P0
0
K0
0
control bit
Note: "R" represents read enabled, and "W" represents write enabled.
2-60
Return condition
P flag
1
0
at reset : 0000
0
key-on wakeup
3
1
0
key-on wakeup
1
1
key-on wakeup 0
3
1
0
key-on wakeup
1
1
4513/4514 Group User's Manual
Set the port using the key-on wakeup function selected
with register K0 to "H" level before going into the RAM
back-up state because the port P0 shares the falling
edge detection circuit with port P1.
Select the return level ("L" level or "H" level) with the bit
2 of register I1 according to the external state before
going into the RAM back-up state.
Select the return level ("L" level or "H" level) with the bit
2 of register I2 according to the external state before
going into the RAM back-up state.
Software start
P = "1"
?
Cold start

Fig. 2.9.1 Start condition identified example

at RAM back-up : state retained
2
Key-on wakeup not used
Key-on wakeup used
Key-on wakeup not used
Key-on wakeup used
Key-on wakeup not used
Key-on wakeup used
Key-on wakeup not used
Key-on wakeup used
Remarks
Yes
No
Warm start
–P0 , P1
0 3
–P1 .
0 3
R/W