STM32串口中 USART_GetITStatus 与 USART

一、ITStatus USART_GetITStatus(USART_TypeDef* USARTx, uint16_t USART_IT)在判断相应位是否置1（读SR寄存器）前会先判断相应位的中断是否使能（读CR寄存器）。

所以若使用 while(USART_GetITStatus(USART1,USART_IT_TC) != SET); 来进行判断数据是否发送完成，

注意需使能TC中断 USART_ITConfig(USART1, USART_IT_TC, ENABLE); 否则会一直返回0导致死在while里。

/*** @brief  Checks whether the specified USART interrupt has occurred or not.* @param  USARTx: Select the USART or the UART peripheral. *   This parameter can be one of the following values:*   USART1, USART2, USART3, UART4 or UART5.* @param  USART_IT: specifies the USART interrupt source to check.*   This parameter can be one of the following values:*     @arg USART_IT_CTS:  CTS change interrupt (not available for UART4 and UART5)*     @arg USART_IT_LBD:  LIN Break detection interrupt*     @arg USART_IT_TXE:  Tansmit Data Register empty interrupt*     @arg USART_IT_TC:   Transmission complete interrupt*     @arg USART_IT_RXNE: Receive Data register not empty interrupt*     @arg USART_IT_IDLE: Idle line detection interrupt*     @arg USART_IT_ORE:  OverRun Error interrupt*     @arg USART_IT_NE:   Noise Error interrupt*     @arg USART_IT_FE:   Framing Error interrupt*     @arg USART_IT_PE:   Parity Error interrupt* @retval The new state of USART_IT (SET or RESET).*/
ITStatus USART_GetITStatus(USART_TypeDef* USARTx, uint16_t USART_IT)
{uint32_t bitpos = 0x00, itmask = 0x00, usartreg = 0x00;ITStatus bitstatus = RESET;/* Check the parameters */assert_param(IS_USART_ALL_PERIPH(USARTx));assert_param(IS_USART_GET_IT(USART_IT));/* The CTS interrupt is not available for UART4 and UART5 */ if (USART_IT == USART_IT_CTS){assert_param(IS_USART_123_PERIPH(USARTx));}   /* Get the USART register index */usartreg = (((uint8_t)USART_IT) >> 0x05);/* Get the interrupt position */itmask = USART_IT & IT_Mask;itmask = (uint32_t)0x01 << itmask;if (usartreg == 0x01) /* The IT  is in CR1 register */{itmask &= USARTx->CR1;}else if (usartreg == 0x02) /* The IT  is in CR2 register */{itmask &= USARTx->CR2;}else /* The IT  is in CR3 register */{itmask &= USARTx->CR3;}bitpos = USART_IT >> 0x08;bitpos = (uint32_t)0x01 << bitpos;bitpos &= USARTx->SR;if ((itmask != (uint16_t)RESET)&&(bitpos != (uint16_t)RESET)){bitstatus = SET;}else{bitstatus = RESET;}return bitstatus;
}

二、FlagStatus USART_GetFlagStatus(USART_TypeDef* USARTx, uint16_t USART_FLAG)直接判断相应位是否置1（读SR寄存器），而不会判断相应中断是否开启，通常可用于没开启相应中断时进行判断，比如只使用了串口接收到数据进入中断时，只需使能 USART_ITConfig(USART1, USART_IT_RXNE, ENABLE); 无需再使能多余的中断。

void USART1_IRQHandler(void)
{u8 res;if(USART_GetITStatus(USART1,USART_IT_RXNE) != RESET)//Receive Data register not empty interrupt{res = USART_ReceiveData(USART1); while(USART_GetFlagStatus(USART1,USART_FLAG_TXE) != SET);//判断发送缓冲区是否空USART_SendData(USART1,res);while(USART_GetFlagStatus(USART1,USART_FLAG_TC) != SET);//while(USART_GetITStatus(USART1,USART_IT_TC) != SET);//需使能TC中断}USART_ClearFlag(USART1,USART_FLAG_TC);//USART_ClearITPendingBit(USART1,USART_IT_TC); //与USART_ClearFlag同种效果
}

/*** @brief  Checks whether the specified USART flag is set or not.* @param  USARTx: Select the USART or the UART peripheral. *   This parameter can be one of the following values:*   USART1, USART2, USART3, UART4 or UART5.* @param  USART_FLAG: specifies the flag to check.*   This parameter can be one of the following values:*     @arg USART_FLAG_CTS:  CTS Change flag (not available for UART4 and UART5)*     @arg USART_FLAG_LBD:  LIN Break detection flag*     @arg USART_FLAG_TXE:  Transmit data register empty flag*     @arg USART_FLAG_TC:   Transmission Complete flag*     @arg USART_FLAG_RXNE: Receive data register not empty flag*     @arg USART_FLAG_IDLE: Idle Line detection flag*     @arg USART_FLAG_ORE:  OverRun Error flag*     @arg USART_FLAG_NE:   Noise Error flag*     @arg USART_FLAG_FE:   Framing Error flag*     @arg USART_FLAG_PE:   Parity Error flag* @retval The new state of USART_FLAG (SET or RESET).*/
FlagStatus USART_GetFlagStatus(USART_TypeDef* USARTx, uint16_t USART_FLAG)
{FlagStatus bitstatus = RESET;/* Check the parameters */assert_param(IS_USART_ALL_PERIPH(USARTx));assert_param(IS_USART_FLAG(USART_FLAG));/* The CTS flag is not available for UART4 and UART5 */if (USART_FLAG == USART_FLAG_CTS){assert_param(IS_USART_123_PERIPH(USARTx));}  if ((USARTx->SR & USART_FLAG) != (uint16_t)RESET){bitstatus = SET;}else{bitstatus = RESET;}return bitstatus;
}

总结：我认为在GetITStatus和GetFlagStatus不仅在串口中是这种区别，在其他地方比如外部中断中使用也是类似道理。

以上为本人现阶段学习中所认为，若有错误希望指出相互学习谢谢！

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