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68HC705JJ7_1 参数 Datasheet PDF下载

68HC705JJ7_1图片预览
型号: 68HC705JJ7_1
PDF下载: 下载PDF文件 查看货源
内容描述: 常规版本规格 [General Release Specification]
分类和应用:
文件页数/大小: 230 页 / 5548 K
品牌: FREESCALE [ Freescale ]
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Freescale Semiconductor, Inc.  
Inte rrup ts  
NOTE: The response of the IRQ/V pin can be affected if the external interrupt  
PP  
capability of the PA0 through PA3 pins is enabled. If the port A pins are  
enabled as external interrupts, then any high level on a PA0–PA3 pin will  
cause the IRQ changes and state to be ignored until all of the PA0–PA3  
pins have returned to a low level.  
4.6.2 PA0–PA3 Pins  
Programming the PIRQ bit in the MOR to a logic one enables the  
PA0–PA3 pins (PA0:3) to serve as additional external interrupt sources.  
A rising edge on a PA0:3 pin latches an external interrupt request. After  
completing the current instruction, the CPU tests the IRQ latch. If the  
IRQ latch is set, the CPU then tests the I bit in the condition code register  
and the IRQE bit in the ISCR. If the I bit is clear and the IRQE bit is set,  
the CPU then begins the interrupt sequence. The CPU clears the IRQ  
latch while it fetches the interrupt vector, so that another external  
interrupt request can be latched during the interrupt service routine. As  
soon as the I bit is cleared during the return from interrupt, the CPU can  
recognize the new interrupt request.  
The PA0:3 pins can be edge-triggered or edge- and level-triggered.  
External interrupt triggering sensitivity is selected by the LEVEL bit in the  
MOR.  
With the edge- and level-sensitive trigger MOR option, a rising edge or  
a high level on a PA0:3 pin latches an external interrupt request. The  
edge- and level-sensitive trigger MOR option allows connection to a  
PA0:3 pin of multiple wired-OR interrupt sources. As long as any source  
is holding the pin high, an external interrupt request is present, and the  
CPU continues to execute the interrupt service routine.  
With the edge-sensitive only trigger MOR option, a rising edge on a  
PA0:3 pin latches an external interrupt request. A subsequent external  
interrupt request can be latched only after the voltage level of the  
previous interrupt signal returns to a logic zero and then rises again to a  
logic one.  
General Release Specification  
MC68HC705JJ7/MC68HC705JP7 Rev. 3.0  
Interrupts  
For More Information On This Product,  
Go to: www.freescale.com  
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