7751 Group User’s Manual
INTERRUPTS
4–12
The following explains the operation of the interrupt priority detection circuit using Figure 4.5.2.
The interrupt priority level of a requested interrupt (Y in Figure 4.5.2) is compared with the resultant priority
level sent from the preceding comparator (X in Figure 4.5.2); whichever interrupt of the higher priority level
is sent to the next comparator (Z in Figure 4.5.2). (Initial comparison value is “0.”) For interrupts for which
no interrupt request occurs, the priority level sent from the preceding comparator is forwarded to the next
comparator. When the two priority levels are found the same by comparison, the priority level sent from the
preceding comparator is forwarded to the next comparator. Accordingly, when the same priority level is set
by software, the interrupt requests are subject to the following relation about priority:
A-D conversion > UART1 transmit > UART1 receive > UART0 transmit > UART0 receive > Timer B2
____
____
____
> Timer B1 > Timer B0 > Timer A4 > Timer A3 > Timer A2 > Timer A1 > Timer A0 > INT
2
> INT
1
> INT
0
Among the multiple interrupt requests sampled at the same time, one that has the highest priority level is
detectedd by the above comparison.
Then this highest interrupt priority level is compared with the processor interrupt priority level (IPL). When
this interrupt priority level is higher than the processor interrupt priority level (IPL) and the interrupt disable
flag (I) is “0,” the interrupt request is accepted. A interrupt request which is not accepted here is retained
until it is accepted or its interrupt request bit is cleared to “0” by software.
The interrupt priority is detected when the CPU fetches an op code, which is called the CPU’s op-code fetch
cycle. However, when an op-code fetch cycle is generated during detection of an interrupt priority, new
detection of that does not start. (Refer to Figure 4.6.1.) Since the state of the interrupt request bit and
interrupt priority levels are latched during detection of interrupt priority, even if the bit state and priority
levels change, the detection is performed on the previous state before it has changed.
4.5 Interrupt priority level detection circuit
Fig. 4.5.2 Interrupt priority level detection model
Y
X
Z
Comparator
(Priority level
comparison)
●
When X
Y then Z = X
●
When X
Y then Z = Y
Interrupt source Y
X : Resultant priority level sent from the preceding
comparator (Highest priority at this point)
Y : Priority level of interrupt source Y
Z : Highest priority at this point
Time
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Содержание 7700 FAMILY
Страница 2: ...MITSUBISHI 16 BIT SINGLE CHIP MICROCOMPUTER 7700 FAMILY 7751 SERIES 7751 Group User s Manual...
Страница 11: ...Table of Contents viii 7751 Group User s Manual MEMORANDUM...
Страница 12: ...CHAPTER 1 DESCRIPTION 1 1 Performance overview 1 2 Pin configuration 1 3 Pin description 1 4 Block diagram...
Страница 48: ...CHAPTER 3 INPUT OUTPUT PINS 3 1 Programmable I O ports 3 2 I O pins of internal peripheral devices...
Страница 157: ...TIMER B 6 28 7751 Group User s Manual 6 5 Pulse period pulse width measurement mode MEMORANDUM...
Страница 245: ...7751 Group User s Manual 8 36 A D CONVERTER Precautions when using A D converter MEMORANDUM...
Страница 246: ...CHAPTER 9 WATCHDOG TIMER 9 1 Block description 9 2 Operation description 9 3 Precautions when using watchdog timer...
Страница 254: ...CHAPTER 10 STOP MODE 10 1 Clock generating circuit 10 2 Operation description 10 3 Precautions for Stop mode...
Страница 260: ...CHAPTER 11 WAIT MODE 11 1 Clock generating circuit 11 2 Operation description 11 3 Precautions for Wait mode...
Страница 265: ...7751 Group User s Manual WAIT MODE 11 6 11 3 Precautions for Wait mode MEMORANDUM...
Страница 289: ...CONNECTION WITH EXTERNAL DEVICES 12 4 Hold function 7751 Group User s Manual 12 24 MEMORANDUM...
Страница 290: ...CHAPTER 13 RESET 13 1 Hardware reset 13 2 Software reset...
Страница 302: ...CHAPTER 14 CLOCK GENERATING CIRCUIT 14 1 Oscillation circuit example 14 2 Clock...
Страница 307: ...CLOCK GENERATING CIRCUIT 7751 Group User s Manual 14 6 14 2 Clock MEMORANDUM...
Страница 359: ...ELECTRICAL CHARACTERISTICS 7751 Group User s Manual 15 52 MEMORANDUM 15 15 Testing circuit for ports P0 to P8 1 and E...
Страница 360: ...CHAPTER 16 STANDARD CHARACTERISTICS 16 1 Standard characteristics...
Страница 365: ...STANDARD CHARACTERISTICS 16 1 Standard characteristics 7751 Group User s Manual 16 6 MEMORANDUM...
Страница 366: ...CHAPTER 17 APPLICATIONS 17 1 Memory expansion...
Страница 405: ...APPLICATIONS 7751 Group User s Manual 17 40 17 1 Memory expansion MEMORANDUM...
Страница 406: ...CHAPTER 18 PROM VERSION 18 1 EPROM mode 18 2 Usage precaution...
Страница 417: ...7751 Group User s Manual PROM VERSION 18 12 18 2 Usage precaution MEMORANDUM...
Страница 418: ...CHAPTER 19 FLASH MEMORY VERSION 19 1 Parallel input output mode 19 2 Serial input output mode...
Страница 451: ...FLASH MEMORY VERSION 7751 Group User s Manual 19 34 19 2 Serial input output mode MEMORANDUM...
Страница 483: ...APPENDIX 7751 Group User s Manual 20 32 Appendix 4 Package outlines Appendix 4 Package outlines 80P6N A...
Страница 484: ...APPENDIX 7751 Group User s Manual 20 33 Appendix 4 Package outlines 80D0...
Страница 489: ...APPENDIX 7751 Group User s Manual 20 38 Appendix 6 Hexadecimal instruction code table...
Страница 490: ...APPENDIX 7751 Group User s Manual 20 39 Appendix 6 Hexadecimal instruction code table...
Страница 491: ...APPENDIX 7751 Group User s Manual 20 40 Appendix 7 Machine instructions Appendix 7 Machine instructions...
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Страница 535: ...APPENDIX Appendix 9 Q A 7751 Group User s Manual 20 84 MEMORANDUM...
Страница 536: ...GLOSSARY...
Страница 539: ...GLOSSARY 7751 Group User s Manual 4 MEMORANDUM...