NIOS2 essay--DMA (1)

1. NIOS2 DMA controller Structural block diagram

650) this.width=650; "src=" http://s2.51cto.com/wyfs02/M02/86/14/wKioL1e0FhOgQLM0AABV0YChFOY335.jpg "title=" Dma_ Block.jpg "width=" "height=" 195 "border=" 0 "hspace=" 0 "vspace=" 0 "style=" width:600px;height:195px; "alt=" Wkiol1e0fhogqlm0aabv0ychfoy335.jpg "/>

Like other IP peripherals, the DMA controller also implements the register configuration and data reading and writing functions via the Avalon mm bus.

2. NIOS2 DMA three modes of transmission
650) this.width=650; "src=" http://s2.51cto.com/wyfs02/M01/86/14/wKioL1e0FvjiUQ-ZAAChmJyhnjQ108.jpg "title=" Dma_ 3trans.jpg "width=" "height=" 513 "border=" 0 "hspace=" 0 "vspace=" 0 "style=" width:600px;height:513px; "alt=" Wkiol1e0fvjiuq-zaachmjyhnjq108.jpg "/>

3. NIOS2 DMA API function

NIOS2 DMA API function prototypes are defined in the ALT_DMA.H header file, the usual API functions are as follows:

alt_dma_txchan alt_dma_txchan_open  (const char* name); static alt_inline int  alt_dma_txchan_send  (alt_dma_txchan dma,               const void* from,               alt_u32 length,              alt_txchan_done* done,               void* handle) {  return dma ? dma->dma_send   (dma,         from,          length,        done,          handle)  : -enodev;} static alt_inline int alt_dma_txchan_ioctl  (alt_dma_txchan dma,               int             req,                void*          arg ) {  return dma ? dma->ioctl  (Dma, req, arg)  : -ENODEV;} alt_dma_rxchan alt_dma_rxchan_open  (Const char* dev);static alt_inline int  alt_dma_rxchan_prepare  (alt_dma_rxchan   dma,                                                  void*            data,                                                 alt_u32          len,                                                 alt_rxchan_done* done,                                                   void*             handle) { &Nbsp;return dma ? dma->prepare  (Dma, data, len, done, handle)  :  -enodev;} static alt_inline int alt_dma_rxchan_ioctl  (alt_dma_rxchan dma,                int             req,                VOID*          ARG) {   return dma ? dma->ioctl  (Dma, req, arg)  : -enodev;}

4. Reference Design--onchipmenmory to SDRAM

1) Qsys Settings

The NIOS2 code runs in SDRAM, and onchipmemory acts as an on-chip storage peripheral.

The following two figures are the IP settings in the Qsys, which shows that DMA supports burst read-write mode, which can greatly improve efficiency.

In the second picture, the blogger checked the show signals option to see the signal interface defined by the DMA component, a Avalon mm slave port for the configuration register, two Avalon mm Masters to read and write, and an IRQ interrupt output, Generates an interrupt signal to the CPU.

650) this.width=650; "src=" http://s5.51cto.com/wyfs02/M01/86/14/wKioL1e0F77xnOH4AAC2JfTl0N4138.jpg "title=" DAM_ Set0.jpg "width=" "height=" 414 "border=" 0 "hspace=" 0 "vspace=" 0 "style=" width:600px;height:414px; "alt=" Wkiol1e0f77xnoh4aac2jftl0n4138.jpg "/>

650) this.width=650; "src=" http://s2.51cto.com/wyfs02/M01/86/15/wKiom1e0F-LBCPE6AAC95qBBTc8052.jpg "title=" Dma_ Set1.jpg "width=" "height=" 508 "border=" 0 "hspace=" 0 "vspace=" 0 "style=" width:600px;height:508px; "alt=" Wkiom1e0f-lbcpe6aac95qbbtc8052.jpg "/>

2) Software source code

File name:main.c//date:2016.8.15//author:shugen.yin//function:dma, onchip memory to  sdram/ddr2//log: #include  <stdio.h> #include  <string.h> #include  <sys/alt_ irq.h> #include   "system.h" #include   "alt_types.h" #include   "sys/alt_dma.h" #define  dat_len  32unsigned int buffer0[dat_len/4];unsigned int *point=onchip_memory1_0_base;static  void dma_init (void);  //initialization Dmaunsigned int dma_end_flag = 0;alt_dma_txchan  tx;alt_dma_rxchan rx;void dma_done () {dma_end_flag++;} Static void dma_init (void) {Tx = alt_dma_txchan_open ("/dev/dma_0"); if (tx != null) {printf ("dma transition start\n");} Alt_dma_txchan_ioctl (tx,alt_dma_set_mode_32,null);//point is the source address, the length of the transmitted data block is Dat_lenalt_dma_txchan_send (tx,  Point, dat_len, null, null); Rx = alt_dma_rxchan_open ("/dev/dma_0"); Alt_dma_rxchan_ IOCTL (Rx,alt_dma_set_mode_32,null);//buffer0 is the destination address, the length of the transmitted data block is Dat_len, Dma_done () is the callback function called after the DMA is completed Alt_dma_rxchan_prepare (RX,&NBSP;BUFFER0  , dat_len, dma_done, null);} Int main () {int i;for (i=0;i<dat_len/4;i++) buffer0[i] = 0;for (i=0;i<DAT_LEN/4;i++) * ( Point+i)  = i+1;//initializes the Dmadma_init ();//waits for the end of the interrupt, indicating that the transfer is complete while (dma_end_flag == 0) {}//Prints the data for the receive address for ( i=0;i<dat_len/4;i++) {printf ("buffer0[%d]=%d\t", I,buffer0[i]);} Alt_dma_txchan_close (TX); Alt_dma_rxchan_close (rx); return 0;}

This article is from the "Shugenyin blog" blog, make sure to keep this source http://shugenyin.blog.51cto.com/4259554/1839585

NIOS2 essay--DMA (1)