GPIO_InitTypeDef 	GPIO_Handle = {0}; 
/* init GPIO Alternate Function */
GPIO_Handle.Pin       = GPIO_PIN_6|GPIO_PIN_7;
GPIO_Handle.Mode      = GPIO_MODE_AF_PP;
GPIO_Handle.Pull      = GPIO_PULLUP;
GPIO_Handle.Alternate = GPIO_FUNCTION_5;
gpio_init(GPIO_A, &GPIO_Handle);

/* init uart1 */   
Uart1_handle.UARTx = Uart1;
Uart1_handle.Init.BaudRate   = 115200;
Uart1_handle.Init.DataLength = UART_DATA_LENGTH_8BIT;
Uart1_handle.Init.StopBits   = UART_STOPBITS_1;
Uart1_handle.Init.Parity     = UART_PARITY_NONE;
Uart1_handle.Init.FIFO_Mode  = UART_FIFO_ENABLE;
uart_init_ex(&Uart1_handle);

__UART_INT_RX_ENABLE(Uart1_handle.UARTx);
NVIC_EnableIRQ(UART1_IRQn);

/* init uart1 rx DMA */ 

DMA_Chan2.Channel               = DMA_Channel2;
DMA_Chan2.Init.Data_Flow        = DMA_P2M_DMAC;
DMA_Chan2.Init.Request_ID       = 3;
DMA_Chan2.Init.Source_Inc       = DMA_ADDR_INC_NO_CHANGE;
DMA_Chan2.Init.Desination_Inc   = DMA_ADDR_INC_INC;
DMA_Chan2.Init.Source_Width     = DMA_TRANSFER_WIDTH_8;
DMA_Chan2.Init.Desination_Width = DMA_TRANSFER_WIDTH_8;
dma_init(&DMA_Chan2);

__SYSTEM_DMA_CLK_ENABLE();
NVIC_EnableIRQ(DMA_IRQn);
uart_receive_DMA(&Uart1_handle);
__UART_RxFIFO_THRESHOLD((&Uart1_handle), 1);//Set RxFIFO 1/4 full  

dma_start(&DMA_Chan2, (uint32_t)&Uart1_handle.UARTx->DATA_DLL.DATA,(uint32_t)Checkbuf, 200, DMA_BURST_LEN_4, DMA_BURST_LEN_1);

}
void DMA_disable(DMA_HandleTypeDef hdma)
{
/ Disable the channel /
DMA->Misc_Reg.ChEnReg = (DMA->Misc_Reg.ChEnReg&(~(1 << hdma->Channel))) | (1 << (hdma->Channel + 8));
/ Clear Transfer complete status /
dma_clear_tfr_Status(hdma->Channel);
/ channel Transfer complete interrupt disable */
dma_tfr_interrupt_disable(hdma->Channel);
}
attribute((section("ram_code"))) void uart1_isr(void)
{
uint32_t isr_id;

volatile struct_UART_t * const uart_reg_ram = (volatile struct_UART_t *)UART1_BASE;

isr_id = __UART_INT_GET_ID(Uart1_handle.UARTx);
if((isr_id & 0x0f) == 0x0c)
{
	if(dma_recv_idx == 0)
	{
		dma_recv_idx = DMA->Channels[DMA_Chan2.Channel].CTL2.BLOCK_TS;
		co_printf("dma_recv_idx:%d\r\n",dma_recv_idx);
	}
	while(uart_reg_ram->LSR.LSR_BIT.DR)
	{
		Checkbuf[dma_recv_idx++] = (uint8_t)uart_reg_ram->DATA_DLL.DATA;
	}
	recv_done= 1;
}

}
主循环中
while(1)
{
if(recv_done)
{
recv_done = 0;
DMA_disable(&DMA_Chan2);
dma_start(&DMA_Chan2, (uint32_t)&Uart1_handle.UARTx->DATA_DLL.DATA,(uint32_t)Checkbuf, 200, DMA_BURST_LEN_4, DMA_BURST_LEN_1);
co_printf("recv done:%d\r\n",dma_recv_idx);
show_reg(Checkbuf,dma_recv_idx,1);
dma_recv_idx = 0;
}
}