NRF52832 SDK15.3 FPU功能配置

• keil中配置

• 在sdk_config.h中配置

  // <q> NRF_PWR_MGMT_CONFIG_FPU_SUPPORT_ENABLED  - Enables FPU event cleaning.
   
  
  #ifndef NRF_PWR_MGMT_CONFIG_FPU_SUPPORT_ENABLED
  #define NRF_PWR_MGMT_CONFIG_FPU_SUPPORT_ENABLED 1
  #endif

• 定義FPU相關宏

  #define FPU_EXCEPTION_MASK               0x0000009F                      //!< FPU exception mask used to clear exceptions in FPSCR register.
  #define FPU_FPSCR_REG_STACK_OFF          0x40                            //!< Offset of FPSCR register stacked during interrupt handling in FPU part stack.
  

• 使能FPU中斷

      NVIC_SetPriority(FPU_IRQn, APP_IRQ_PRIORITY_LOWEST);
      NVIC_ClearPendingIRQ(FPU_IRQn);
      NVIC_EnableIRQ(FPU_IRQn);

• FPU中斷處理函數

/**
 * @brief FPU Interrupt handler. Clearing exception flag at the stack.
 *
 * Function clears exception flag in FPSCR register and at the stack. During interrupt handler
 * execution FPU registers might be copied to the stack (see lazy stacking option) and
 * it is necessary to clear data at the stack which will be recovered in the return from
 * interrupt handling.
 */
void FPU_IRQHandler(void)
{
    // Prepare pointer to stack address with pushed FPSCR register.
    uint32_t * fpscr = (uint32_t * )(FPU->FPCAR + FPU_FPSCR_REG_STACK_OFF);
    // Execute FPU instruction to activate lazy stacking.
    (void)__get_FPSCR();
    // Clear flags in stacked FPSCR register.
    *fpscr = *fpscr & ~(FPU_EXCEPTION_MASK);
}

以上步驟是使能硬件FPU功能操作