Intel 80C188XL Interrupt Mask Register, Imask, Masks individual interrupt sources, Register Name

Models: 80C186XL 80C188XL

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Interrupt Mask Register

INTERRUPT CONTROL UNIT

Register Name:

Interrupt Mask Register

Register Mnemonic:

IMASK

Register Function:

Masks individual interrupt sources

15

I

I

I

I

 

D

D

N

N

N

N

 

M

M

T

T

T

T

 

A

A

3

2

1

0

 

1

0

 

 

 

 

 

 

 

0

T

M

R

A1202-A0

Bit

Bit Name

Reset

Function

Mnemonic

State

 

 

 

 

 

 

INT3:0

External

0000 0

Set a bit to mask (disable) interrupt requests

 

Interrupt

 

from the corresponding external interrupt pin.

 

Mask

 

 

 

 

 

 

DMA1:0

DMA

0

Set to mask (disable) interrupt requests from

 

Interrupt

 

the corresponding DMA channel .

 

Mask

 

 

 

 

 

 

TMR

Timer

0

Set to mask (disable) interrupt requests from

 

Interrupt

 

the timers.

 

Mask

 

 

 

 

 

 

NOTE: Reserved register bits are shown with gray shading. Reserved bits must be written to a logic zero to ensure compatibility with future Intel products.

Figure 8-8. Interrupt Mask Register

8.4.4Priority Mask Register

The Priority Mask register (Figure 8-9) contains a three-level field that holds a priority value. This register allows you to mask interrupts based on their priority levels. Write a priority value to the PM2:0 field to specify the lowest priority interrupt to be serviced. This disables (masks) any interrupt source whose priority is lower than the PM2:0 value. After reset, the Priority Mask register is set to the lowest priority (seven), which enables all interrupts of any priority.

8-17

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Intel 80C188XL, 80C186XL Interrupt Mask Register, Imask, Masks individual interrupt sources, 8.4.4Priority Mask Register