8.3.10Priority Mask Register (PRIMSK, Offset 2Ah) (Master Mode)

The Priority Mask (PRIMSK) Register provides the value that determines the minimum priority level at which maskable interrupts can generate an interrupt.

Figure 8-13 Priority Mask Register (PRIMSK, offset 2Ah)

15

7

0

0 0 0 0 0 0 0 0 0

0 0 0 0

PRM2

PRM1

PRM0

The value of PRIMSK at reset is 0007h.

Bits 15–3: Reserved —Set to 0.

Bits 2–0: Priority Field Mask (PRM2–PRM0) —This field determines the minimum priority that is required for a maskable interrupt source to generate an interrupt. Maskable interrupts with programmable priority values that are numerically higher than this field are masked. The possible values are zero (000b) to seven (111b).

A value of seven (111b) allows all interrupt sources that are not masked to generate interrupts. A value of five (101b) allows only unmasked interrupt sources with a programmable priority of zero to five (000b to 101b) to generate interrupts.

Table 8-4 Priority Field Mask (Master Mode)

Priority

PR2–PR0

 

 

(High) 0

0 0 0b

 

 

1

0 0 1b

 

 

2

0 1 0b

 

 

3

0 1 1b

 

 

4

1 0 0b

 

 

5

1 0 1b

 

 

6

1 1 0b

 

 

(Low) 7

1 1 1b

 

 

8-24

Interrupt Control Unit

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AMD Am186TMER, Am188TMER Priority Mask Register PRIMSK, Offset 2Ah Master Mode, Priority Field Mask Master Mode PR2-PR0