如何设置UART接收中断

我很难弄清楚如何设置UART接收中断。我设法得到了例子TX和RX代码，并修改了TX和RX OK，但我需要做以下，不知道如何设置这一点，以及如何在中断中访问变量。
我有2个应用程序。第一个方面如下：
当接收到每个字节时，RX中断中的状态机。
RX引脚不断切换。一个字节的引导和序列标记开始分组，所以我需要丢弃不想要的字节，直到检测到导入序列，然后将字节收集到缓冲器中，直到接收到正确的字节数为止。
我是否把RX缓冲区设置为最小，这样程序就在每个RX字节上产生中断，然后把我的状态机放到UARTHARRX.C中？
第二个应用更简单，因为它可以接收整个包BVEI之前，我需要处理任何东西。但这一个，我希望一个定时器被重置每次字节到达，然后20毫秒后，最后一个字节，定时器将到期，我设置了一个标志，以指示DATAN BUBF。另外，如果PSoC具有某种标准组件THA可以使用XON/XOFF进行分组接收，则可以改变分组结构。
数据包长度是动态的。
谢谢



     以下为原文
   I am having trouble figuring out how to set up the UART Receive interrupt. I managed to get gthe example TX and RX code and modified for TX and RX ok but I need to do the following and not sure how to set this up and how to access variables in the interrupt.
    I have 2 applications. The first is as follows:
    State Machine within RX interrupt as each Byte is received.
    The RX pin is continuously toggling. A leading and sequence of bytes marks start of packet so I need to discard unwanted bytes until the lead-in sequence is detected and then gather bytes into a buffer until the correct number of bytes is received.
    Do I just set the RX buffer to minimum so the program generates interrupt on each RX byte and then put my state machine into UART_RX.C ?
    The second application is simpler in that it can receive the entire packet bvefore I need to process anything. But this one I want a timer to be reset every time a byte arrives and then 20ms after last byte the timer will expire and I set a flag to indicate DatainBuf. Alternately I can change packet structure if the PSOC has some sort of standard component tha can use XON/XOFF for packet reception.
    The packet lengty is dynamic.
    Thanks