M37733MHBXXXFP Datasheet, PDF (14/89 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

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MITSUBISHI MICROCOMPUTERS
M37733MHBXXXFP
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
As shown in Figure 9, there are three different interrupt priority
detection time from which one is selected by software. After the
selected time has elapsed, the interrupt which has the highest priority
is determined and is processed after the current instruction execution
has been completed.
The time is selected with bits 4 and 5 of the processor mode register
0 (address 5E16) shown in Figure 10. Table 4 shows the relationship
between these bits and the number of cycles. After a reset, the
processor mode register 0 is initialized to “0016”. Therefore, the longest
time is selected. However, the shortest time should be selected by
software.
Table 3. Value set in processor interrupt level (IPL) during an interrupt
Interrupt types
Setting value
Reset
0
DBC
7
Watchdog timer
7
Zero divide
Not change value of IPL.
BRK instruction
Not change value of IPL.
Table 4. Relationship between interrupt priority detection time selec-
tion bits and number of cycles
Interrupt priority detection time selection bits
Bit 5
Bit 4
0
0
0
1
1
0
Number of cycles
7 cycles of φ
4 cycles of φ
2 cycles of φ
φ : internal clock
Internal clock φ
Operation code fetch cycle
Sampling pulse
Priority detection time
0
Select one from 0 to 2 with 1
bits 4 and 5 of the
processor mode register 0 ₂
Fig. 9 Interrupt priority detection time
76543210
0
Fig. 10 Processor mode register 0 configuration
Address
Processor mode register 0 (5E 16)
Processor mode bits
0 0 : Single-chip mode
0 1 : Memory expansion mode
1 0 : Microprocessor mode
Wait bit
0 : Wait
1 : No wait
Software reset bit
The processor is reset when this bit is set to “1” .
Interrupt priority detection time selection bits
0 0 : Select 0 in Figure 9
0 1 : Select 1 in Figure 9
1 0 : Select 2 in Figure 9
Always “0”
Clock φ 1 output selection bit
0 : No φ 1 output
1 : φ 1 output
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