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INTERRUPT CONTROLLER S3C2410A
14-14
INTERRUPT PENDING (INTPND) REGISTER
Each of the 32 bits in the interrupt pending register shows whether the corresponding interrupt request, which is
unmasked and waits for the interrupt to be serviced, has the highest priority . Since the INTPND register is located
after the priority logic, only one bit can be set to 1, and that interrupt request generates IRQ to CPU. In interrupt
service routine for IRQ, you can read this register to determine which interrupt source is serviced among the 32
sources.
Like the SRCPND register, this register has to be cleared in the interrupt service routine after clearing the SRCPND
register. We can clear a specific bit of the INTPND register by writing a data to this register. It clears only the bit
positions of the INTPND register corresponding to those set to one in the data. The bit positions corresponding to
those that are set to 0 in the data remains as they are.
Register Address R/W Description Reset Value
INTPND 0X4A000010 R/W Indicate the interrupt request status.
0 = The interrupt has not been requested.
1 = The interrupt source has asserted the interrupt
request.
0x00000000
NOTES:
1. If the FIQ mode interrupt occurs, the corresponding bit of INTPND will not be turned on as the INTPND register is
available only for IRQ mode interrupt.
2. Cautions in clearing the INTPND register.
The INTPND register is cleared to "0" by writing "1". If the INTPND bit, which has "1", is cleared by "0", the INTPND
register & INTOFFSET register may have unexpected value in some case.
So, you never write "0" on the INTPND bit having "1". The convenient method to clear the INTPND register is writing the
INTPND register value on the INTPND register. (In even our example code, this guide hasn't been applied yet.)