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RAM BACKUP MODE
19
19-7
32185/32186 Group Hardware Manual
Rev.1.10 REJ09B0235-0110 May 15, 07
19.3 Example of RAM Backup for Saving Power Consumption
19.3.2 RAM Backup State
Figure 19.3.3 shows the RAM backup state of the M32R/ECU. Figure 19.3.4 shows a RAM backup se-
quence. When the external circuit outputs "L," input on the SBI# or AD0INi pin is pulled "L." "L" on these
input pins generates a RAM backup signal (A and (a) in Figure 19.3.3). To enable RAM backup mode,
make the following settings:
(1) Create data for RAM check to verify after returning from RAM backup mode to normal mode
whether the RAM data has been retained normally ((b) in Figure 19.3.3).
(2) To materialize low-power operation, set all programmable input/output pins except port n for
input mode (or for output mode, with the output level fixed "L") ((c) in Figure 19.3.3).
(3) Set port n for input mode (B and (d) in Figure 19.3.3). This causes the transistor’s base voltage,
IB,to go "L," so that the power to all power supply pins except VDDE is shut off (C and D in
Figure 19.3.3).
By settings in (1) to (3), the VDDE pin voltage goes to 3.0–5.5 V and all other pin voltages drop to 0 V, and
the M32R/ECU is thereby placed in RAM backup mode ((d) in Figure 19.3.3).
Figure 19.3.3 RAM Backup State for Low Power Operation
"L"
B
C
(a)
(b)
(c)
(d)
"L"
IB
0V
A
D
DC IN
VREF0
SBI#
AD0INi
M32R/ECU
VDDE
AVCC0
VCCE,
VCCER
EXCVCC
EXCVDD
VCC-
BUS
3.3V or 5V
(5V or 3.3V)
Example of RAM backup processing
RAM backup signal
External circuit
Port n
(Note 1)
(Note 3)
RAM backup power supply
Regulator
Input
Output
Regulator
(Note 2)
Output
Note 1: This circuit outputs "L" during RAM backup.
Note 2: This port outputs "H" when the power is on, and is set for input mode
when in RAM backup mode (one of the port pins selected).
Note 3: These pins are used to detect a RAM backup signal.
Note 4: Determined by the input level on SBI# pin or AD0INi pin.
Note 5: Base voltage IB = 0 causes the power to all power supply pins except VDDE
to stop.
See A to D in the above explanation.
Generate a RAM backup signal
(Note 4)
Create data for
backup RAM check
Set the pin connecting to the
transistor's base (port n)
for input mode
(Note 5)
RAM backup mode