m3819 Renesas Electronics Corporation., m3819 Datasheet - Page 181

• Manufacturer Part Number: m3819
• Description: Mitsubishi 8-bit Single-chip Microcomputer 740 Family / 38000 Series
• Manufacturer: Renesas Electronics Corporation.

2. APPLICATION
Fig. 2.9.19 Control procedure (1) [Counting without clock errors during a power failure]
Control procedure : Set the related registers in the order shown below to prepare for a power failure.
N
Recovery processing from a power failure
CPUM
T1
T12M
T34M
T34M
IREQ1
IREQ2
Base counter
1second counter
ICON1
Initialization
T12M
ICON1
CPUM
CPUM
IREQ1
IREQ2
T1
T2
T3
ICON2(Address:3F
CPUM (Address:3B
Execute the WIT instruction
(Address:3B
(Address:20
(Address:28
(Address:29
(Address:29
(Address:3C
(Address:3D
(Address:3E
(Address:28
(Address:3E
(Address:3B
(Address:3B
(Address:3C
(Address:3D
(Address:20
(Address:21
(Address:22
Be concluded the condition
recovered from a power failure?
Detect a power failure?
(Internal RAM)
(Internal RAM)
RESET
~ ~
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
)
)
), bit6, bit0
), bit2
), bit6
), bit6
), bit0
), bit6
Y
16
Y
), bit2
)
)
)
), bit6
), bit7
), bit5
), bit6
), bit0
), bit0
16
), bit4
1
0
1(Note)
1(Note)
0
0
8–1
256–1
16–1
1
3819 Group USER’S MANUAL
1
0
64–1
00
0
1
0
0
256–1
16–1
1
16
N
Middle-speed mode
Select the X
Main clock division ratio : select the high-speed
Set for being count the base and 1 second
counters during the Timer 1 interrupts.
In the normal power state, these software
counters generate one second.
Timer 1 count source : f(X
Timer 1 interrupt : Disabled
Internal system clock : select the low-speed
Main clock f(X
Set for generating the Timer 3 interrupts every
second.
Generate 1 second by the hardware timer during
a power failure.
Timer 3 interrupt : Enabled
Generate the Timer 3 interrupts every second
(recover from a wait mode)
Note : Do not switch at the same time.
2.9 Clock generating circuit
CIN
IN
-X
) : Stopped
~ ~
COUT
oscillating function
mode f(X
mode
CIN
)
MITSUBISHI MICROCOMPUTER
CIN
).
3819 Group
167