Ah I understand your confusion now.
The ipending register does not contain the configuration of interrupts, rather the interrupts that have been raised and currently need servicing (i.e. the corresponding peripherals have raised their lanes).
By default the Interval Timer IP will raise an interrupt every time interval as specified in your instance parameters. So it may happen quite often. If you don't service these interrupts, the lane stay up, and so does ipending.
The only way to clear ipending is for the CPU to access your peripheral and perform the specific operation that the device needs to lower the interrupt lane value (often you will write to some control register through a bus write to notify the device that you took care of it).
Let me know if it's still unclear,
Cheers,
The TAs
