Enable\Disable Interrupts

[autukuri]

Posted on July 29, 2008 at 19:01

Enable\Disable Interrupts

[autukuri]

Posted on May 17, 2011 at 12:40

Is there a quick way to temporarily disable and enble the interrupts on the Cortex? I have a critical timing loop which varies in time due to USB, DMA, and other interrupts. Is there a way to suspend interrupts for a few microseconds? I have worked with other ST parts (like the ST7) that had assembly instructions to perform this task. I am unable to find this info in the datasheet.

Thanks in advance.

[joseph239955]

Posted on May 17, 2011 at 12:40

You can use the PRIMASK register. When it is set to 1, it disable all

exception except hard fault exception and NMI exception.

To do this, you can use assembler instruction

CPSID I

or

MOVS r0, #1

MSR PRIMASK, r0 ; move R0 into PRIMASK

To re-enable interrupt, you can use

CPSIE I

or

MOVS r0, #0

MSR PRIMASK, r0

If you use RealView Compiler, or KEIL RealView Microcontroller Development Kit, you can use C functions

__disable_irq();

and

__enable_irq();

(http://www.keil.com/support/man/docs/armccref/armccref_cjafbcbb.htm)

Or if you are using the ST firmware library, you can use the functions defined in cortexm3_macros.h

void __SETPRIMASK(void); // disable interrupts

void __RESETPRIMASK(void); // enable interrupts

or functions in stm32f10x_nvic.h

void NVIC_SETPRIMASK(void); // disable interrupts

void NVIC_RESETPRIMASK(void); // enable interrupts

which I believe has the same functions.

[disirio]

Posted on May 17, 2011 at 12:40

''cpsid i'' disables interrupts, ''cpsie i'' re-enables them. Another option is to modify the BASEPRI register.

regards,

Giovanni

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