如何检测UART是否准备好了它的传输

嗨，社区，最近我遇到了一个问题，如何检测UART是否准备好了它的传输。这并不像乍看起来那么容易。UART有多达3个区域，其中要传输的数据是：第一缓冲器（当在模块配置中定义）第二FIFO，4字节深度保存未发送数据，从中断例程第三中的缓冲器中提供字节，通常被遗忘，Tx移位寄存器，实际上持有。传输字节
获取缓冲区是否已经空的信息的API是UARTHGETGETXBuffResiSe（），它不返回名称所暗示的大小，而是返回缓冲区中使用的字节数。因此返回值为0（零）表示空缓冲区。
为了看看FIFO状态，我们有API UARTHARETCTXSTATUSER（），它不仅指示一个空的FIFO和一个位掩码
UARTHXTXYSTSH FIFOSY空，但指示TX移位寄存器的完整传输与掩蔽名为UARTHARTXYSTSSO完成。遗憾的是，当用API读取时，该位被重置。
当编写一个函数返回UART的忙状态时，我们必须考虑以下事实：缓冲器必须是空的FIFO必须是空的传输必须完成。
问题是，当查看“传输必须完成”时，API将状态设置为“传输不完全”，这会在下一个繁忙的UART返回“忙”的情况下回答，而当等待“准备”UART时，这个答案会导致无限循环。
因此，给出正确结果的函数有点复杂。我在这篇文章中附上一篇。
什么时候需要这个功能？传输数据时的所有管理都是由提供的UART例程来处理的，所以不需要。但是当你必须停止UART的时候
原因（主要是进入睡眠模式），你必须确保所有的通信。
这里的功能是：
Uti8UARTHOLL（空隙）{UTIN STS；静态UIT8 FILSTSTIMECTORACE= TRUE；Y定义忙1 / /只为了更好地阅读（我希望）
St= UARTHEADTXXSTATUS（）；如果（！）（（uart_gettxbuffersize() = = 0）&；&；（STS &；uart_tx_sts_fifo_empty）））/ /串口缓冲区是空的吗？{ firsttimecalled = false；返回忙；/ /缓冲器不空，返回“忙”}其他/ / UART缓冲区是空的，但最后一个字节可以转移目前{ if（STS &；uart_tx_sts_complete）/ /转移完成？位叫uart_readtxstatus() { firsttimecalled =真正的复位；/ /是的，我们做的回报！忙；}其他/ /转移没有完成或叫后第一时间！忙返回{if（第一次调用）返回！忙；返回忙；}{undf繁忙}
玩得开心鲍伯



     以下为原文
  Hi Community,
lately I came over the question how to detect if an UART is ready with its transmission.
This is not as easy as it seems as first sight. An UART has up to 3 areas where the data to be transmitted is stored:
1st The buffer (when defined in the module configuration)
2nd The FIFO, 4 bytes deep holding untransmitted data, fed with bytes from Buffer in the interrupt routine
3rd Often forgotten, the Tx-shift-register, holding the actually transmitted byte
    An API to get information whether the buffer is already empty is UART_GetTxBufferSize() which does not return the
size as the name would suggest, but the number of used bytes in the buffer. Thus a returned value of 0 (zero) indicates an empty buffer.
    To have a look at the FIFO state we have the API UART_ReadTxStatus() which not only indicates an empty FIFO with a bit-mask named
    UART_TX_STS_FIFO_EMPTY but indicates a complete transmission of the tx-shift-register with a mask named UART_TX_STS_COMPLETE.
Unfortunately this bit is reset when read with the API.
    When writing a function to return the busy state of an UART we have to consider following facts:
Buffer must be empty
FIFO must be empty
Transfer must be complete.
    The problem is, when looking at "Transfer must be complete" the API sets the state to "Transfer NOT complete" which would at a next
questioning for a busy UART return "Busy" and this answer can lead into an infinite loop when waiting for a "Ready" UART.
    So, a function to give a correct result is a bit complicated. I append one to this post.
    When is the function needed?
All the management when transfering data is handled by the supplied UART-routines, so there is no need. But when you have to stop the UART for any
    reason (mostly to enter sleep mode) you must be sure that all communication is made.
    Here is the function:
     
     
   
uint8 UART_Busy(void)
{
uint8 STS;
static uint8 FirstTimeCalled = TRUE;
#define Busy 1 // Just for better readabiliy (I hope)
    STS = UART_ReadTxStatus();
if (!((UART_GetTxBufferSize() == 0) && (STS & UART_TX_STS_FIFO_EMPTY))) // Are the UART buffers empty?
{
FirstTimeCalled = FALSE;
return Busy; // Buffers NOT empty, return "Busy"
}
else // UART buffers empty, but last byte may be transfered currently
{
if (STS & UART_TX_STS_COMPLETE) // Is Transfer completed? Bit was reset with call to UART_ReadTxStatus()
{
FirstTimeCalled = TRUE; // Yes, we are done
return !Busy;
}
else // Transfer not completed or called the first time after a !Busy returned
{
if (FirstTimeCalled) return !Busy;
return Busy;
}
}
#undef Busy
}
     
     
    Have fun
Bob