M34282M2-XXXGP View Datasheet(PDF) - MITSUBISHI ELECTRIC
Part Name
Description
Manufacturer
M34282M2-XXXGP Datasheet PDF : 70 Pages
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MITSUBISHI MICROCOMPUTERS
4282 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER
WATCHDOG TIMER
Watchdog timer provides a method to reset and restart the system
when a program runs wild. Watchdog timer consists of 14-bit
timer (WDT) and watchdog timer flags (WDF1, WDF2).
Watchdog timer downcounts the instruction clock (INSTCK) as
the count source immediately after system is released from reset.
When the timer WDT count value becomes 000016 and underflow
occurs, the WDF1 flag is set to “1.” Then, when the WRST
instruction is not executed before the timer WDT counts 16383,
WDF2 flag is set to “1” and internal reset signal is generated and
system reset is performed.
Execute the WRST instruction at period of 16383 machine cycle
or less to keep the microcomputer operation normal.
Timer WDT is also used for generation of oscillation stabilization
time. When system is returned from reset and from RAM back-
up mode by key-input, software starts after the stabilization
oscillation time until timer WDT downcounts to 3E0016 elapses.
Software start
3FFF16
3E0016
Value of timer WDT
Software start
WDF1 flag
WDF2 flag
0000 16
“1”
“0”
“1”
“0”
Internal reset signal “H”
“L”
System
reset
POF
instruction
execution
Return
WRST
instruction
execution
Software start
System
reset
Fig. 17 Watchdog timer function
LOGIC OPERATION FUNCTION
The 4282 Group has the 4-bit logic operation function. The logic
operation between the contents of register A and the low-order
4 bits of register E is performed and its result is stored in register
A.
Table 5 Logic operation selection register LO
Each logic operation can be selected by setting logic operation
selection register LO.
Set the contents of this register through register A with the TLOA
instruction. The logic operation selected by register LO is
executed with the LGOP instruction.
Table 5 shows the logic operation selection register LO.
Logic operation selection register LO
at reset : 002
at RAM back-up : 002
W
LO1
Logic operation selection bits
LO0
LO1 LO0
Logic operation function
0 0 Exclusive logic OR operation (XOR)
0 1 OR operation (OR)
1 0 AND operation (AND)
1 1 Not available
Note: “W” represents write enabled.
MITSUBISHI
16
ELECTRIC
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