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319973-003 参数 Datasheet PDF下载

319973-003图片预览
型号: 319973-003
PDF下载: 下载PDF文件 查看货源
内容描述: 英特尔I / O控制器中枢10 [Intel I/O Controller Hub 10]
分类和应用: 控制器
文件页数/大小: 840 页 / 5889 K
品牌: INTEL [ INTEL ]
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Functional Description  
5.8.4.2  
Special Fully-Nested Mode  
This mode is used in the case of a system where cascading is used, and the priority has  
to be conserved within each slave. In this case, the special fully-nested mode is  
programmed to the master controller. This mode is similar to the fully-nested mode  
with the following exceptions:  
• When an interrupt request from a certain slave is in service, this slave is not locked  
out from the master's priority logic and further interrupt requests from higher  
priority interrupts within the slave are recognized by the master and initiate  
interrupts to the processor. In the normal-nested mode, a slave is masked out  
when its request is in service.  
• When exiting the Interrupt Service routine, software has to check whether the  
interrupt serviced was the only one from that slave. This is done by sending a Non-  
Specific EOI command to the slave and then reading its ISR. If it is 0, a non-  
specific EOI can also be sent to the master.  
5.8.4.3  
5.8.4.4  
5.8.4.5  
Automatic Rotation Mode (Equal Priority Devices)  
In some applications, there are a number of interrupting devices of equal priority.  
Automatic rotation mode provides for a sequential 8-way rotation. In this mode, a  
device receives the lowest priority after being serviced. In the worst case, a device  
requesting an interrupt has to wait until each of seven other devices are serviced at  
most once.  
There are two ways to accomplish automatic rotation using OCW2; the Rotation on  
Non-Specific EOI Command (R=1, SL=0, EOI=1) and the rotate in automatic EOI mode  
which is set by (R=1, SL=0, EOI=0).  
Specific Rotation Mode (Specific Priority)  
Software can change interrupt priorities by programming the bottom priority. For  
example, if IRQ5 is programmed as the bottom priority device, then IRQ6 is the highest  
priority device. The Set Priority Command is issued in OCW2 to accomplish this, where:  
R=1, SL=1, and LO–L2 is the binary priority level code of the bottom priority device.  
In this mode, internal status is updated by software control during OCW2. However, it  
is independent of the EOI command. Priority changes can be executed during an EOI  
command by using the Rotate on Specific EOI Command in OCW2 (R=1, SL=1, EOI=1,  
and LO–L2=IRQ level to receive bottom priority.  
Poll Mode  
Poll mode can be used to conserve space in the interrupt vector table. Multiple  
interrupts that can be serviced by one interrupt service routine do not need separate  
vectors if the service routine uses the poll command. Poll mode can also be used to  
expand the number of interrupts. The polling interrupt service routine can call the  
appropriate service routine, instead of providing the interrupt vectors in the vector  
table. In this mode, the INTR output is not used and the microprocessor internal  
Interrupt Enable flip-flop is reset, disabling its interrupt input. Service to devices is  
achieved by software using a Poll command.  
The Poll command is issued by setting P=1 in OCW3. The PIC treats its next I/O read as  
an interrupt acknowledge, sets the appropriate ISR bit if there is a request, and reads  
the priority level. Interrupts are frozen from the OCW3 write to the I/O read. The byte  
returned during the I/O read contains a 1 in bit 7 if there is an interrupt, and the binary  
code of the highest priority level in bits 2:0.  
Datasheet  
125  
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