topic what is "spurious interrupt requests" mean? in S12 / MagniV Microcontrollers

what is "spurious interrupt requests" mean?

zy — Wed, 25 Jul 2012 16:23:00 GMT

Hello! anybody

I am using Periodic Interrupt Timer with XET256 ,there is a NOTE in MC9S12XEP100 Reference Manual 17.4.2

Be careful when resetting the PITE, PINTE or PITCE bits in case of pending
PIT interrupt requests, to avoid spurious interrupt requests.

what is mean?

If there is a interrupt request pending ,then I clear PITIE,and PITCE, there is still have a interrupt request pending?

Re: what is "spurious interrupt requests" mean?

kef — Wed, 01 Aug 2012 14:58:56 GMT

It will cost you just one byte of nonbanked flash (one RTI instruction) to provide empty spurious interrupt handler and not worry about it any more.

Spurious interrupt may happen in the case when specific interrupt is disabled after interrupt is signalled, but before interrupt source is recognised. It is something like you phone rings, you are interrupted, but you hear beeps instead of someone's voice.