Hi,
抱歉这么长时间才回复你的帖子。
RT的eDMA模块和之前很多系列产品的模块都是相同的，所以之前一些产品，例如Kinetis，MPC56xx关于eDMA的应用笔记同样适用于RT产品。我这里列举了一些关于eDMA的应用笔记供你参考：
AN4522
AN4765
回到你提出的eDMA如何支持循环buffer，可以参考下面的例程，希望对你有所启发：
eDMA提供modulo特性，使用 circular buffer 接受/发送数据。
For example if you want to transfer each byte as it is received by LINFlex UART into a circular buffer, that will have 16 8-bit entries you will set the TCD as below (assume using LINFlex0 and TCD[0]):
uint8_t buffer[16]; // should be aligned to even address
EDMA_0.TCD[0].SADDR = ((vuint32_t) &LINFLEX_0.BDRM.R + 3);
EDMA_0.TCD[0].SMOD = 0;
EDMA_0.TCD[0].SSIZE = 0; // Source data size = 8bit
EDMA_0.TCD[0].SLAST = 0;
EDMA_0.TCD[0].SOFF = 0; // Source address signed offset = 0
EDMA_0.TCD[0].DMOD = 4; // least significant 4 address bits are changed, providing circular queue of 16 bytes
EDMA_0.TCD[0].DSIZE = 0; // Destination data transfer size = 8 bit
EDMA_0.TCD[0].NBYTES = 1; // Transfer 1 byte per minor loop
EDMA_0.TCD[0].DADDR = ((vuint32_t) &buffer[0]) ;
EDMA_0.TCD[0].CITER = 1;
EDMA_0.TCD[0].DOFF = 1; // After transfer, add 1 to dest addr
EDMA_0.TCD[0].DLAST_SGA = 0;
EDMA_0.TCD[0].BITER = 1;
EDMA_0.TCD[0].BWC = 0;
EDMA_0.TCD[0].MAJORLINKCH = 0;
EDMA_0.TCD[0].DONE = 0;
EDMA_0.TCD[0].ACTIVE = 0;
EDMA_0.TCD[0].MAJORE_LINK = 0;
EDMA_0.TCD[0].E_SG = 0;
EDMA_0.TCD[0].D_REQ = 0;
EDMA_0.TCD[0].INT_HALF = 0;
EDMA_0.TCD[0].INT_MAJ = 0;
EDMA_0.TCD[0].START = 0;
EDMA_0.DMAERQL.R = 0x00000001; // eDMA request signal for channel 0 is enabled
DMAMUX_0.CHCONFIG[0].R |= 0x97; // route LINFlex0 RX DMA request to eDMA channel 0
关于eDMA半完成触发中断，之后无法再次触发。
需要查看中断处理速度是否匹配中断发生的速度，另外中断标志位有没有及时清除。
也可以查看eDMA Error Status (ES) 寄存器，看看eDMA配置是否存在问题。
祝顺利。
Mike
