
Interrupt Control Unit
7-33
7.4.7
Priority Mask Register
(PRIMSK, Offset 2Ah)
(Slave Mode)
The format of the Priority Mask register is shown in Figure 7-22. The Priority Mask register
provides the value that determines the minimum priority level at which maskable interrupts
can generate an interrupt.
Figure 7-22
Priority Mask Register
The value of the PRIMSK register at reset is 0007h.
Bits 15–3: Reserved
Bits 2–0: Priority Field Mask (PRM2–PRM0)—This field determines the minimum priority
which 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 7-6
Priority Level
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
15
7
0
PRM0
PRM2
PRM1
Reserved
Содержание Am186 ES
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Страница 22: ...Features and Performance 1 8...
Страница 60: ...System Overview 3 28...
Страница 84: ...Chip Select Unit 5 14...
Страница 132: ...Timer Control Unit 8 8...
Страница 166: ...Programmable I O Pins 11 6...
Страница 184: ...Register Summary A 18...