217
6.6 External Interrupt Request Levels
6.6
External Interrupt Request Levels
When an edge is selected for the interrupt request mode, a pulse width of at least three
machine cycles (peripheral clock machine cycles) is required to detect an edge.
When a level is selected for the interrupt request mode, an external request that has
been input may be canceled later, though the request issued to the interrupt controller
remains active because an interrupt cause hold circuit exists inside.
The interrupt request register must be cleared to cancel the request issued to the
interrupt controller.
■
External Interrupt Request Levels
Figure 6.6-1 shows how the interrupt cause hold circuit is cleared when a level is selected for
the interrupt request mode. Figure 6.6-2 shows the input of an interrupt cause in interrupt
enable mode and a request issued to the interrupt controller.
Figure 6.6-1 Clearing the Interrupt Cause Hold Circuit at Level Setting for the Interrupt Request Mode
Figure 6.6-2 Input of an Interrupt Cause in Interrupt Enable Mode and a Request Issued to the Interrupt
Controller
Level
detection
Input of interrupt
Cause F/F
(cause hold circuit)
The cause is held until the flip-flop is cleared.
Enable gate
To the interrupt
controller
H level
Interrupt request to
the interrupt controller
Input of interrupt
Clearing the interrupt cause flip-flop deactivates the signal.
Summary of Contents for MB91F109
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Page 96: ...72 CHAPTER 2 CPU ...
Page 224: ...200 CHAPTER 4 BUS INTERFACE ...
Page 234: ...210 CHAPTER 5 I O PORTS ...
Page 268: ...244 CHAPTER 9 U TIMER ...
Page 290: ...266 CHAPTER 10 UART ...
Page 314: ...290 CHAPTER 12 16 BIT RELOAD TIMER ...
Page 322: ...298 CHAPTER 13 BIT SEARCH MODULE ...
Page 392: ...368 CHAPTER 16 FLASH MEMORY ...
Page 432: ...408 APPENDIX E Instructions F Table E 2 Instruction Formats OP rel11 5 11 ...
Page 448: ...424 APPENDIX E Instructions ...
Page 449: ...425 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
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