无法在dspic33ev256上循环TX ISR

我刚刚更新了我的XIDE并安装了XC 16编译器。我取消了dspic33ev256gm106。我写TX ISR例程有困难。由于某些原因，TX ISR没有经过成功的迭代。我在使用皮克特3。跟踪原应用程序TX调用后的TX ISR触发。然而，ISR从来没有中断过。我在ISR中休息，只看到它被击中一次。我不确定，如果我遗漏了什么。请帮助：



      以下为原文

    I have just updated my XIDE and installed the XC 16 compiler. I am unsing dspic33ev256gm106.
I am having trouble writing a TX ISR routine.

For some reason, the TX ISR does not go through successful iterations. I am using Pickit3. I trace TX ISR firing after the original application tx call. However, ISR never breaks ever again. I put a break in the ISR and only see it being hit once. I am not sure, if I am missing something. Please help:)


void uart2_init(void)
{
    //rx_buffer[RX_BUFFER_SIZE];
    rx_buffer_size = 0;
    rx_buffer_max_size = RX_BUFFER_SIZE;
    rx_buffer_head = 0;
    rx_buffer_tail = 0;

    //tx_buffer[TX_BUFFER_SIZE];
    tx_buffer_size = 0;
    tx_buffer_max_size = TX_BUFFER_SIZE;
    tx_buffer_head = 0;
    tx_buffer_tail = 0;

    /* digital input & output */
     _TRISC12 = 1; // Input
     _TRISB7 = 0; // output

    // map UART2 TX pin to port RB7, which is remappable RP39
    _RP39R = 0x03;
    /* map UART2 RX pin to port RC12, which is remappable RP160 */
    RPINR19bits.U2RXR = 0x3C;

    // set up the UART for default baud, 1 start, 1 stop, no parity
    U2MODEbits.LPBACK = 0; // disable LOOPBACK
    U2MODEbits.UEN = 0;
    U2MODEbits.ABAUD = 0; // Auto-Baud disabled
    U2MODEbits.STSEL = 0; // 1-stop bit
    U2MODEbits.PDSEL0 = 0; // No Parity, 8-Data bits
    U2MODEbits.PDSEL1 = 0;
    U2MODEbits.BRGH = 0; // Standard-Speed mode
                         // 4 clock cycles per bit, 0 - 16 cycles per bit
    U2STAbits.URXISEL0 = 0;
    U2STAbits.URXISEL1 = 0; // Interrupt after TX buffer done
    U2STAbits.UTXISEL0 = 0;
    U2STAbits.UTXISEL1 = 1; // Interrupt after TX buffer done

    U2BRG = 11;// BRGH - 0, Baud Rate setting for 115200 (default)
               // 44 if BRGH is 1

    IEC1bits.U2TXIE = 1; // Enable UART TX interrupt
    IEC1bits.U2RXIE = 1; // Enable UART RX interrupt
    U2MODEbits.UARTEN = 1; // Enable UART (this bit must be set *BEFORE* UTXEN)
    //U2STAbits.UTXEN = 1; // Enable the hardware control of the pin and link it to UART2

}



int uart2_send_packet(unsigned char *message, int length)
{
    int i = 0;
    if( ((tx_buffer_tail+1)%tx_buffer_max_size)==tx_buffer_head )
    {
        // buffer is full
        return 0;
    }
    else
    {
        // load up as many bytes as possible
        while ( (((tx_buffer_tail+1)%tx_buffer_max_size)!=tx_buffer_head ) && i         {
            tx_buffer[tx_buffer_tail] = message;
            i++;
            tx_buffer_tail = (tx_buffer_tail+1)%tx_buffer_max_size;
            tx_buffer_size++;
        }
        U2STAbits.UTXEN = 1;
        return i;
    }
}




void __attribute__((interrupt, no_auto_psv)) _U2TXInterrupt(void)
{
    IFS1bits.U2TXIF = 0; // Clear TX2 Interrupt flag
    if( tx_buffer_head!=tx_buffer_tail)
    {
        // there are things left to send
        while (U2STAbits.TRMT==0);
        U2TXREG = tx_buffer[tx_buffer_head];
        tx_buffer_head = (tx_buffer_head+1)%tx_buffer_max_size;
        tx_buffer_size--;
    }
    else
    {
        U2STAbits.UTXEN = 0;
    }
}

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