如何循环基于DMA必须适当的工作定义解决4096个字节的传输缓冲区的限制？

你好，
我的工作项目以模拟样本的SAR ADC使用DMA，放入缓冲区1位于RAM，完成填充缓冲区后，切换到填充缓冲区2。而DMA填充缓冲区，缓冲区是通过串口传送给PC使用的CPU。而缓冲2完成灌装、DMA开始aggain填满缓冲区1和2是通过UART发送缓冲区。这个过程是循环的。
每笔交易以每2字节DMA突发ADC（ADC工作在12位分辨率）和传输数256（每个DMA transactiontakes ADC，128样本而样本2字节）。
（总和）后4096字节通过throughdma我开始从DMA得到错误的数据。
我的问题是：
我怎么能更新中转柜台（我想看看通过debuggeronphub_tdmem [XXX] - 12位ofxfrcnt）？
如何循环基于DMA必须适当的工作定义，解决了4096个字节的传输缓冲区的限制？
谢谢您。
亚历克斯



     以下为原文
  Hello,
    I am working on project which takes analog samples from SAR ADC using DMA, put them into the buffer 1 located in RAM, after it finishes filling buffer, it switches to fill buffer 2. While DMA fills buffer 2, buffer 1 is transmitted to pc using CPU via uart. While filling of buffers 2 finishing, the DMA start aggain to fill buffer 1 and buffer 2 is transmitted via uart. The process is cyclic.
    Each transaction of DMA takes 2 bytes per burst from ADC (ADC operates at resolution of 12 bits) and transfers count is 256 (each DMA transaction takes 128 samples from ADC, while each sample is 2 bytes).
    After 4096 (total sum) of bytes pass through DMA I start to get wrong data from DMA.
    My questions are:
    How I can  update the transfer counter (I tried to take a look via debugger on PHUB_TDMEM[xxx] - 12 bit of XFRCNT)?
    How cyclic processes based on DMA must be defined for proper work, solving the limitation of transfer buffer of 4096 bytes?
    Thank you.
    Alex