readme.txt

基于visual dsp++开发环境

****************************************************************************************************

ADSP-BF533 EZ-KIT Interface to DAC AD9744 Example

Analog Devices, Inc.
DSP Division
Three Technology Way
Norwood, MA 02062

Date Created:	6/06/03

____________________________________________________________________________________________________

This directory contains an example on how to interface the ADSP-BF533 EZ-kit to an AD9744 Evaluation Board 
via the Extender Card.


Files contained in this directory (all source code in C language):

AD9744_DAC.dpj			VisualDSP++  project file
main.c				main routine 
Init PPI.c			initialization of PPI port and DMA channel
Init Timer for PPI.c		initialization of timer 1 for the PPI GP output mode
Init Interrupts.c		initialization and definition of Interrupts and service routine
Init SDRAM.c			initialize SDRAM controller
InitFlash.c			setup flash I/O port
Start PPI.c			Starts data transfer over PPI
readme.txt			this readme file
system.h			header file

____________________________________________________________________________________________________


CONTENTS

I.	FUNCTIONAL DESCRIPTION
II.	IMPLEMENTATION DESCRIPTION
III.	OPERATION DESCRIPTION


I.    FUNCTIONAL DESCRIPTION

	Writes continous streams of data to the DAC. The data is transmitted from a memory buffer via the PPI interface of the ADSP-BF533.


II.   IMPLEMENTATION DESCRIPTION

 	A double buffering scheme is implemented so that data in one half is available for "re-fill" while the other half is being 
	transmitted out via DMA operations. A flag ("Ping_Pong") indicates which half is available for the new data.
	A variety of predefined output signals are #defined in system.h. In the case of SINES being defined, you may also
	define amplitude and frequency. The sinevalues are then precalculated.
						

III.  OPERATION DESCRIPTION

	- follow the "hardware setup" instructions in the main comment header in "main.c"	
	- Open the project "AD9744_ADC.dpj" in the VisualDSP Integrated Development Environment (IDDE).
	- Under the "Project" tab, select "Build Project" (program is then loaded automatically into DSP).
	
	- Select "Run" from the "Debug" tab on the menu bar of VisualDSP.
	- You should see the analog signal from the DAC output on a scope.

	- The main header file "system.h" contains #define statements to change shape of output waveform and buffer size.