DMA不切换缓冲区

嗨，我正在使用一个DSPIC33 EP512MC202和MixStiK II开发工具包。我使用DMA将数据从ADC传输到ED中声明的2个缓冲器。DMA被配置为乒乓模式。我想使用for循环找到缓冲区中的最大值，然后如果该值超过阈值，则关闭DMA/ADC。理想情况下，这将发生在DMA中断中，所以我需要的数据没有被DMA写过。我在中断程序中遇到了一个问题，当我把循环添加到查找最大值时，DMA缓冲区没有被交换。这就是我的中断的样子：我的DMA初始化函数在这里：如果我使用调试器，DMAPPsBIT.PPST0寄存器值一致。如果中断例程不包含循环以查找缓冲区中的最大值，则每次中断0到1之间的ping。使用循环来找到最大值，DMAPPsBIT.PPST0寄存器值保持在0。有人对如何修复这个问题/什么可能出错有什么建议？谢谢！



      以下为原文

    Hi,
       I'm working with a dsPIC33EP512MC202 and a MicroStik II development kit. I'm using the DMA to transfer data from the ADC to 2 buffers declared in EDS. The DMA is configured for ping-pong mode. I would like to use a for loop to find the maximum value in a buffer and then if that value exceeds a threshold to then turn off the DMA/ADC. Ideally, this would occur within the DMA interrupt so that the data that I need is not over-written by the DMA. I'm having an issue with the interrupt routine where the DMA buffers are not being swapped when I add the loop to the find the maximum value.

This is what my interrupt looks like:


void __attribute__ ( ( interrupt, no_auto_psv ) ) _DMA0Interrupt( void )
{  
    //Reset the interrupt flag  
    IFS0bits.DMA0IF = 0;
   
    BUFFER_INDEX = DMAPPSbits.PPST0;
    //IO_RA0_SetHigh();
    if (CURRENT_BUFFER == 0){
        BUFFERA_FULL = 1;
    }
    else{
        BUFFERA_FULL = 0;
    }
   
    if(BUFFERA_FULL == 1){
    //if(BUFFER_INDEX == 2){
        /*CURRENT_BUFFER = 1;*/
        //BUFFERA_FULL = 1;
       //Find the max value in the buffer
       for (i = 0; i < BUFFER_SIZE; i++){
                /*if (BUFFER_A > max){
                    max = BUFFER_A;
                }*/
           max = (max > BUFFER_A?max:BUFFER_A);
        }
    }
    //this was changed to if from else if
    //if (CURRENT_BUFFER == 1){
    else{
        
        /*CURRENT_BUFFER = 0;*/
        //BUFFERA_FULL = 0;
        /*k = DMAPPSbits.PPST0;*/
        for (i = 0; i < BUFFER_SIZE; i++){
                /*if (BUFFER_B > max){
                    max = BUFFER_B;
                }*/
            max = (max > BUFFER_B?max:BUFFER_B);
        }
    }


My DMA initilization function is here:

void DMA_Initialize_1(void)
{
    // Initialize channels which are enabled
    // AMODE Peripheral Indirect Addressing mode; CHEN enabled; DIR Reads from peripheral address, writes to RAM address; HALF Initiates interrupt when half of the data has been moved; SIZE 16 bit; NULLW disabled; MODE Continuous, Ping-Pong modes are enabled;
    //DMA0CON= 0x9022 & 0x7FFF; //Enable DMA Channel later;
    // FORCE disabled; IRQSEL ADC1;
    //DMA0REQ= 0xD;
    // CNT 0;
    //DMA0CNT= BUFFER_SIZE - 1;
    // STA 4096;
    //Initialize the DMA buffers
    //DMA0STAL= 0x1000;
    //Transfer a word at a time
    DMA0CONbits.SIZE = 0;
    //Read from peripheral write to RAM
    DMA0CONbits.DIR = 0;
    //Generate Interrupt when the entire transfer has completed
    //DMA0CONbits.HALF = 0;
    //Generate Interrupt when all of the transfer has completed
    DMA0CONbits.HALF = 0;
    //When the full transfer is complete
    //DMA0CONbits.HALF = 0;
    //Normal operation
    DMA0CONbits.NULLW = 0;
    //DMA Configured for Peripheral Indirect Mode
    //DMA0CONbits.AMODE = 2;
    DMA0CONbits.AMODE = 0;
    //Configure for Continuous Ping-Pong Mode
    DMA0CONbits.MODE = 2;
    DMA0PAD = (int)&ADC1BUF0;
    //ADC1 Selected as DMA Request Source
    DMA0REQ = 13;
    DMA0CNT = ( BUFFER_SIZE - 1 );
    //DMA0CNT = 7;
   
    DMA0STAL = __builtin_dmaoffset(&BUFFER_A);
    DMA0STAH = __builtin_dmapage(&BUFFER_A);
    /*DMA0STAL = __builtin_dmaoffset(&gDataBuff);
    DMA0STAH = __builtin_dmapage(&gDataBuff);*/
    /*DMA0STAL =&BUFFER_A;
    DMA0STAH = &BUFFER_A;*/
    //DMA0STAH = 0x0000;
    DMA0STBL = __builtin_dmaoffset(&BUFFER_B);
    DMA0STBH = __builtin_dmapage(&BUFFER_B);
    /*DMA0STBL = &BUFFER_B;
    DMA0STBH = &BUFFER_B;*/
    //DMA0STBH = 0x0000;
    // STA 0;
    //DMA0STAH= 0x0;
    // Clearing Channel 0 Interrupt Flag;
    IFS0bits.DMA0IF = false;
    // Enabling Channel 0 Interrupt
    IEC0bits.DMA0IE = 1;

    //Enable DMA Channel 0
   
    DMA0CONbits.CHEN = 1;
}


If I go through using the debugger the DMAPPSbits.PPST0 register value consistently ping-pongs between 0 and 1 every time the interrupt fires if the interrupt routine does not contain the loop to find the max value in the buffer. With the loop to find the maximum value the DMAPPSbits.PPST0 register values stays at 0.

Does anyone have any advice on how to fix this issue/what might be going wrong? Thanks!