INTERRUPT STRUCTURE S3C8245/P8245/C8249/P8249
5-10
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.
Interrupt Mask Register (IMR)
DDH, Set 1, R/W
.7 .6 .5 .4 .3 .2 .1 .0MSB LSB
IRQ1
IRQ2
IRQ4
IRQ5
IRQ6
IRQ7
IRQ0
IRQ3
NOTE:
Before IMR register is changed to any value, all interrupts must be disable.
Using DI instruction is recommended.
Interrupt level enable bits (7-4, 2-0):
0 = Disable (mask) interrupt level
1 = Enable (un-mask) interrupt level
Figure 5-6. Interrupt Mask Register (IMR)