Interrupt Mask Register (Imr) - Samsung S3C8275X User Manual

INTERRUPT STRUCTURE

INTERRUPT MASK REGISTER (IMR)

The interrupt mask register, IMR (set 1, DDH) is used to enable or disable interrupt processing for individual
interrupt levels. After a reset, all IMR bit values are undetermined and must therefore be written to their required
settings by the initialization routine.
Each IMR bit corresponds to a specific interrupt level: bit 1 to IRQ1, bit 2 to IRQ2, and so on. When the IMR bit of
an interrupt level is cleared to "0", interrupt processing for that level is disabled (masked). When you set a level's
IMR bit to "1", interrupt processing for the level is enabled (not masked).
The IMR register is mapped to register location DDH in set 1. Bit values can be read and written by instructions
using the Register addressing mode.
MSB
NOTE:
5-10
Interrupt Mask Register (IMR)
DDH, Set 1, R/W
.7 .6 .5 .4
IRQ4
IRQ5
IRQ6
IRQ7
Before IMR register is changed to any value, all interrupts must be disable.
Using DI instruction is recommended.
Figure 5-6. Interrupt Mask Register (IMR)
S3C8275X/F8275X/C8278X/F8278X/C8274X/F8274X
.3 .2 .1 .0
IRQ0
IRQ1
IRQ2
IRQ3
Interrupt level enable bits:
0 = Disable (mask) interrupt level
1 = Enable (un-mask) interrupt level
LSB