CMSIS 头文件的bug

只看该作者 · 2012-12-11 12:13

问题出在函数 NVIC_GetPriority



__STATIC_INLINE uint32_t NVIC_GetPriority(IRQn_Type IRQn)

{

  if(IRQn < 0) {

    return((uint32_t)((SCB->SHP[_SHP_IDX(IRQn)] >> _BIT_SHIFT(IRQn) ) >> (8 - __NVIC_PRIO_BITS)));  } /* get priority for Cortex-M0 system interrupts */

  else {

    return((uint32_t)((NVIC->IP[ _IP_IDX(IRQn)] >> _BIT_SHIFT(IRQn) ) >> (8 - __NVIC_PRIO_BITS)));  } /* get priority for device specific interrupts  */

}

这里移位时发生了错误，高位没有去除。
例如：如果 IRQn == 26 ，并且 NVIC->IP[ _IP_IDX(IRQn)] == 0x40404040,
函数返回优先级为 0x101.

实际上正确的返回值应为 1

代码修正如下

复制



__STATIC_INLINE uint32_t NVIC_GetPriority(IRQn_Type IRQn)

{

  if(IRQn < 0) {

    return 0xFF & ((uint32_t)((SCB->SHP[_SHP_IDX(IRQn)] >> _BIT_SHIFT(IRQn) ) >> (8 - __NVIC_PRIO_BITS)));  } /* get priority for Cortex-M0 system interrupts */

  else {

    return 0xFF & ((uint32_t)((NVIC->IP[ _IP_IDX(IRQn)] >> _BIT_SHIFT(IRQn) ) >> (8 - __NVIC_PRIO_BITS)));  } /* get priority for device specific interrupts  */

}