MSP430 Interrupt flag activity

John Malone

Does disabling an individual port 1 or 2 interrupt also disable the associated interrupt flag or does the interrupt flag continue to get set on the active transition of the discrete input even when its interrupt is disabled?

over 13 years ago

0 blb over 13 years ago

Genius 3020 points

Hi,

From the MSP4305xx users guide

" Each PxIFG bit is the interrupt flag for its corresponding I/O pin and is set when the selected input signal
edge occurs at the pin. All PxIFG interrupt flags request an interrupt when their corresponding PxIE bit
and the GIE bit are set."

So flag is set even if the interrupt is disabled.

Barry

0 John Malone over 13 years ago in reply to blb

Prodigy 30 points

Barry,

I read that in the user's guide but when I read the next paragraph I was less certain.

"8.2.7.3 Interrupt Enable P1IE, P2IE

"Each PxIE bit enables the associated PxIFG interrupt flag."

Thanks for the information.

Jack

0 blb over 13 years ago in reply to John Malone

Genius 3020 points

Jack,

I was pretty sure that the flags did get set even if the IE bits were not set, but I ran quick test and verified that flags do get set.

Regards,

Barry

0 John Malone over 13 years ago in reply to blb

Prodigy 30 points

Barry,

Thanks for checking that out, I appreciate your help.

Jack

0 milap patel over 13 years ago in reply to John Malone

Intellectual 805 points

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0 Jens-Michael Gross over 13 years ago in reply to John Malone

Guru 227245 points

John Malone said:
Each PxIE bit enables the associated PxIFG interrupt flag

Well, it does not enable the IFG bit being set, but it enables the IFG bit triggering an interrupt.
Almost all MSP interrupts (except a few system ones) work with an IE/IFG combo. The two bits are ANDed to trigger an interrupt. If teh IE bit is not set, no interrupt will happen, but one can still check the IFG bit.

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MSP430 Interrupt flag activity