STM32F103处理嵌套中断的优先级-Java 学习之路

我可以在STM32F10x库中找到与NVIC_Init相关的问题，该问题与处理嵌套中断的优先级有关 . 我们知道优先级值等于或高于BASEPRI（在我们的例子中为11）的任何中断都可以调用FromISR（）FreeRTOS API函数 .

FreeRTOS使用15级（最低优先级） .

#define configLIBRARY_KERNEL_INTERRUPT_PRIORITY    15

换句话说，FreeRTOS允许我们以15-11优先级从ISR调用API函数（请参阅xQueueSendToBackFromISR） . 当我们初始化NVIC时，我们使用＃11级

#define    WRTU2_DMA1_SPI2_IRQ_PRIORITY     (configLIBRARY_KERNEL_INTERRUPT_PRIORITY-4*)
    /* DMA1 Channel4 interrupt setting */
    NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel4_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = WRTU2_DMA1_SPI2_IRQ_PRIORITY;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = WRTU2_DMA1_SPI2_IRQ_PRIORITY;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

所以，我们应该没问题 . 但问题是存在的 . 我决定检查NVIC_Init .

根据STM32数据表中的信息，优先级寄存器为 0xe000e40e （NVIC通道14属于 DMA1_Channel4 中断） .

NVIC初始化后，我可以从该寄存器中读取 0x00 . 这意味着NVIC通道＃14在系统中具有最高优先级 .

它会导致所有问题 .

我添加了最简单的修复 NVIC->IP[DMA1_Channel4_IRQn] = 0xF0; 并且系统不再失败 . 所以，我们目前的问题已经解决了 .

当然，我试图分析NVIC_Init中发生的事情

**
  * @brief  Initializes the NVIC peripheral according to the specified
  *         parameters in the NVIC_InitStruct.
  * @param  NVIC_InitStruct: pointer to a NVIC_InitTypeDef structure that contains
  *         the configuration information for the specified NVIC peripheral.
  * @retval None
  */
void NVIC_Init(NVIC_InitTypeDef* NVIC_InitStruct)
{
  uint32_t tmppriority = 0x00, tmppre = 0x00, tmpsub = 0x0F;

  /* Check the parameters */
  assert_param(IS_FUNCTIONAL_STATE(NVIC_InitStruct->NVIC_IRQChannelCmd));
  assert_param(IS_NVIC_PREEMPTION_PRIORITY(NVIC_InitStruct->NVIC_IRQChannelPreemptionPriority));  
  assert_param(IS_NVIC_SUB_PRIORITY(NVIC_InitStruct->NVIC_IRQChannelSubPriority));

  if (NVIC_InitStruct->NVIC_IRQChannelCmd != DISABLE)
  {
    /* Compute the Corresponding IRQ Priority --------------------------------*/    
    tmppriority = (0x700 - ((SCB->AIRCR) & (uint32_t)0x700))>> 0x08;
    tmppre = (0x4 - tmppriority);
    tmpsub = tmpsub >> tmppriority;

    tmppriority = (uint32_t)NVIC_InitStruct->NVIC_IRQChannelPreemptionPriority << tmppre;
    tmppriority |=  NVIC_InitStruct->NVIC_IRQChannelSubPriority & tmpsub;
    tmppriority = tmppriority << 0x04;

    NVIC->IP[NVIC_InitStruct->NVIC_IRQChannel] = tmppriority;

    /* Enable the Selected IRQ Channels --------------------------------------*/
    NVIC->ISER[NVIC_InitStruct->NVIC_IRQChannel >> 0x05] =
      (uint32_t)0x01 << (NVIC_InitStruct->NVIC_IRQChannel & (uint8_t)0x1F);
  }
  else
  {
    /* Disable the Selected IRQ Channels -------------------------------------*/
    NVIC->ICER[NVIC_InitStruct->NVIC_IRQChannel >> 0x05] =
      (uint32_t)0x01 << (NVIC_InitStruct->NVIC_IRQChannel & (uint8_t)0x1F);
  }
}

所以，我在我的应用程序中添加了类似的测试代码，以了解它如何转换所有值

uint32_t NVIC_IRQChannelPreemptionPriority=0xFF,NVIC_IRQChannelSubPriority=0xFF;
int32_t tmppriority = 0x00, tmppre = 0x00, tmpsub = 0x0F;
tprintf("\n\rSCB->AIRCR=0x%08x",SCB->AIRCR);

 tmppriority = (0x700 - ((SCB->AIRCR) & (uint32_t)0x700))>> 0x08;
 tprintf("\n\rtmppriority=0x%08x",tmppriority);
tmppre = (0x4 - tmppriority);
tmpsub = tmpsub >> tmppriority;

 tprintf("\n\rtmppre=0x%08x",tmppre);
 tprintf("\n\rtmpsub=0x%08x",tmpsub);


tmppriority = (uint32_t)NVIC_IRQChannelPreemptionPriority << tmppre;
tmppriority |=  NVIC_IRQChannelSubPriority & tmpsub;
tmppriority = tmppriority << 0x04;
tprintf("\n\rtmppriority=0x%08x",tmppriority);

有一个日志

SCB->AIRCR=0xfa050000
tmppriority=0x00000007
tmppre=0xfffffffd
tmpsub=0x00000000
tmppriority=0x00000000

注意，即使我为两个输入参数指定0xFF，它也会返回0x00 .

我对这种行为感到非常惊讶 . 这是一个库函数 .

人们使用它已经很多年了 . 所以，我真的很困惑，我可以找到在该功能中找到问题 .

可能与应用程序中断和复位控制寄存器（SCB_AIRCR）有关地址偏移量：0x0C复位值：0xFA05 0000所需特权：特权AIRCR为异常模型提供优先级分组控制，数据访问的字节序状态和系统复位控制 .

注意，在库中我可以看到 #define AIRCR_VECTKEY_MASK ((uint32_t)0x05FA0000)

因此，看起来我们在16位半字节中有某种BIG vs LITTLE ENDIAN字节顺序 .

你对这个问题有什么建议或知识吗？

STM32F103处理嵌套中断的优先级

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