The difference between the IRQ and FIQ

2, the IRQ can be interrupted by FIQ, but FIQ cannot be interrupted by the IRQ, must be closed when dealing with FIQ interruption,

3, FIQ priority is higher than the IRQ,

4, FIQ mode, more than the IRQ mode R8 ~ R13 backup registers, such as
During compilation, if backup register enough to deal with, not use backup register, do not stack pressure stack and returned after the bomb instruction, improve the efficiency of running

5, FIQ interrupt vector address in 0 x0000001c, and IRQ at 0 x00000018, (in general)

Can put an instruction only 18, in order not to conflict with 1 c in FIQ, this place can only jump, and FIQ, 1 c later without any interruption to the scale, so that we can put directly on the 1 c FIQ interrupt handlers, because of the limit to jump, at least less a jump instruction,