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Zynq DMA Part Two – Adam Taylor’s MicroZed Chronicles Part 29

by Xilinx Employee ‎04-21-2014 09:53 AM - edited ‎04-21-2014 10:16 AM (39,460 Views)

Having introduced Direct Memory Access in my previous blog, this blog will focus upon creating a very simple example which demonstrates how to set up and use DMA. To demonstrate this I will transfer one memory location to another using one DMA controller channel.

 

The starting point for this is one which we have commonly used in this blog series: the inclusion of header files generated as part of the BSP. These header files provide macros and functions we can use to drive the DMA. For this example we will need to include:

 

#include "xscugic.h"

#include "xdmaps.h"

#include "xil_exception.h"


Xscugic.h and xil_exceptions.h allow use of the interrupt controller while xdmaps.h configures and allows use of the DMA.

 

Using parameters provided with xparamters.h, we can define the device identifications for the DMA and interrupt controller, the interrupts that will be used, and the length of the data we will be transferring:

 

#define DMA_DEVICE_ID               XPAR_XDMAPS_1_DEVICE_ID

#define INTC_DEVICE_ID              XPAR_SCUGIC_SINGLE_DEVICE_ID

#define DMA_FAULT_INTR              XPAR_XDMAPS_0_FAULT_INTR

#define DMA_DONE_INTR_0             XPAR_XDMAPS_0_DONE_INTR_0

#define DMA_LENGTH      1024

 

The next stage of the development is to write three functions to configure the DMA, to configure the interrupt controller, and to act as the interrupt service routine at the completion of the DMA transfer.

 

Within the DMA configuration function we first create a DMA command using the command structure provided by xdmaps.h. A DMA command consists of the channel control, block descriptor, a user-defined program, a pointer to the generated program and the result of the transfer. As this is a simple example we will not be requiring all of these components however we will be configuring the DMA controller as below:

 

            DmaCmd.ChanCtrl.SrcBurstSize = 4;

            DmaCmd.ChanCtrl.SrcBurstLen = 4;

            DmaCmd.ChanCtrl.SrcInc = 1;

            DmaCmd.ChanCtrl.DstBurstSize = 4;

            DmaCmd.ChanCtrl.DstBurstLen = 4;

            DmaCmd.ChanCtrl.DstInc = 1;

            DmaCmd.BD.SrcAddr = (u32) Src;

            DmaCmd.BD.DstAddr = (u32) Dst;

            DmaCmd.BD.Length = DMA_LENGTH * sizeof(int);

 

The next step is to initialize and configure the DMA controller before running the interrupt set up function to connect the DMA interrupts to the interrupt controller:

 

DmaCfg = XDmaPs_LookupConfig(DeviceId);

            XDmaPs_CfgInitialize(DmaInst,DmaCfg,DmaCfg->BaseAddress);

            SetupInterrupt(&GicInstance, DmaInst);

 

Following this, the source memory location is seeded with data and the destination location is cleared before we connect the done handler and start the transfer, to track progress we also make one call to the DMA progress function:

 

DmaCfg = XDmaPs_LookupConfig(DeviceId);

            XDmaPs_CfgInitialize(DmaInst,DmaCfg,DmaCfg->BaseAddress);

            SetupInterrupt(&GicInstance, DmaInst);

XDmaPs_Print_DmaProg(&DmaCmd);

 

 

When the attached source code file was run on the MicroZed the following results were shown on the rs232 monitor output I was using to report the status.

 

Figure 1.gif 

 

Having looked at the DMA control and basic example, in my next blog I will be moving on to look at the MicroZed carrier card and how we can use this with the MicroZed as a system of modules.

 

 

 

Please see the previous entries in this MicroZed series by Adam Taylor:

 

The Zynq PS/PL, Part Eight: Zynq DMA – Adam Taylor’s MicroZed Chronicles Part 28  

 

The Zynq PS/PL, Part Seven: Adam Taylor’s MicroZed Chronicles Part 27

 

The Zynq PS/PL, Part Six: Adam Taylor’s MicroZed Chronicles Part 26

 

The Zynq PS/PL, Part Five: Adam Taylor’s MicroZed Chronicles Part 25

 

The Zynq PS/PL, Part Four: Adam Taylor’s MicroZed Chronicles Part 24

 

The Zynq PS/PL, Part Three: Adam Taylor’s MicroZed Chronicles Part 23

 

The Zynq PS/PL, Part Two: Adam Taylor’s MicroZed Chronicles Part 22

 

The Zynq PS/PL, Part One: Adam Taylor’s MicroZed Chronicles Part 21

 

Introduction to the Zynq Triple Timer Counter Part Four: Adam Taylor’s MicroZed Chronicles Part 20

 

Introduction to the Zynq Triple Timer Counter Part Three: Adam Taylor’s MicroZed Chronicles Part 19

 

Introduction to the Zynq Triple Timer Counter Part Two: Adam Taylor’s MicroZed Chronicles Part 18

 

Introduction to the Zynq Triple Timer Counter Part One: Adam Taylor’s MicroZed Chronicles Part 17

 

The Zynq SoC’s Private Watchdog: Adam Taylor’s MicroZed Chronicles Part 16

 

Implementing the Zynq SoC’s Private Timer: Adam Taylor’s MicroZed Chronicles Part 15

 

MicroZed Timers, Clocks and Watchdogs: Adam Taylor’s MicroZed Chronicles Part 14

 

More About MicroZed Interrupts: Adam Taylor’s MicroZed Chronicles Part 13

 

MicroZed Interrupts: Adam Taylor’s MicroZed Chronicles Part 12

 

Using the MicroZed Button for Input: Adam Taylor’s MicroZed Chronicles Part 11

 

Driving the Zynq SoC's GPIO: Adam Taylor’s MicroZed Chronicles Part 10

 

Meet the Zynq MIO: Adam Taylor’s MicroZed Chronicles Part 9

 

MicroZed XADC Software: Adam Taylor’s MicroZed Chronicles Part 8

 

Getting the XADC Running on the MicroZed: Adam Taylor’s MicroZed Chronicles Part 7

 

A Boot Loader for MicroZed. Adam Taylor’s MicroZed Chronicles, Part 6 

 

Figuring out the MicroZed Boot Loader – Adam Taylor’s MicroZed Chronicles, Part 5

 

Running your programs on the MicroZed – Adam Taylor’s MicroZed Chronicles, Part 4

 

Zynq and MicroZed say “Hello World”-- Adam Taylor’s MicroZed Chronicles, Part 3

 

Adam Taylor’s MicroZed Chronicles: Setting the SW Scene

 

Bringing up the Avnet MicroZed with Vivado

 

Comments
by Participant zwm215
on ‎07-15-2014 04:20 PM

Does anyone know if there is a reference implementation that uses DMA with a custom perpheral on the FPGA in order to speed up data transfer (FPGA is in vhdl)?

by Xilinx Employee
on ‎07-15-2014 04:25 PM

@zwm215: You might want to pose this question on one of the Xilinx support forums or the Zedboard support forum. This blog is not really set up for answering your question.

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About the Author
  • Be sure to join the Xilinx LinkedIn group to get an update for every new Xcell Daily post! ******************** Steve Leibson is the Director of Strategic Marketing and Business Planning at Xilinx. He started as a system design engineer at HP in the early days of desktop computing, then switched to EDA at Cadnetix, and subsequently became a technical editor for EDN Magazine. He's served as Editor in Chief of EDN Magazine, Embedded Developers Journal, and Microprocessor Report. He has extensive experience in computing, microprocessors, microcontrollers, embedded systems design, design IP, EDA, and programmable logic.