Interrupt Mask Register (Imr) - Samsung S3C80A5B User Manual

S3C80A5B

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:
Interrupt Mask Register (IMR)
DDH, Set 1, R/W
.7 .6 .5 .4
IRQ7
IRQ6
Not used
IRQ4
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)
.3 .2 .1
IRQ0
IRQ1
Not used
Not used
Interrupt level enable bits (7-6, 4, 1, 0):
0 = Disable (mask) interrupt
1 = Enable (un-mask) interrupt
INTERRUPT STRUCTURE
.0
LSB
5-11