init_dma.c

Using the ADSP-BF561 Blackfin Processor as a TFT-LCD Controller

/*****************************************************************************
**																			**
**	 Project Name: 	LCD											**	
**																			**
******************************************************************************

(C) Copyright 2005 - Analog Devices, Inc.  All rights reserved.

File Name:		Init_DMA.c

Date Modified:	5/1/05		CL		Rev 1.0

Software:       VisualDSP++3.5

Hardware:		ADSP-BF561 EZ-KIT Lite

Special Connections:  None

Purpose:		This file initializes the DMA channel.
				
******************************************************************************/


#include "main.h"
#include "DescriptorDMA_PPI.h"

#define XCNT 429
#define XMOD 4
#define YCNT 525
#define YMOD 4

volatile short config_word;

void Init_DMA_A(volatile short *descript_addr, volatile int *frame_addr){

	char i;
	short descript_size = DESCRIPTOR_SIZE;
	short descript_size_in_bytes;
	
	descript_size_in_bytes = descript_size * sizeof(short);
	descript_size <<= 8;
	config_word = descript_size|DMA_CONFIG;
	
	*pDMA1_0_X_COUNT = XCNT;	// 2 bytes for each pixel, count divided by four if 32-bit DMA transfers are done
	*pDMA1_0_X_MODIFY = XMOD;
	
	*pDMA1_0_Y_COUNT = YCNT;		
	*pDMA1_0_Y_MODIFY = YMOD;
	
	*pDMA1_0_NEXT_DESC_PTR = descript_addr;
	ssync();
		
	for(i=1; i<NUM_BUFFERS; i++){
		*descript_addr = (unsigned short) ((int)(descript_addr)+(int)(descript_size_in_bytes)) & 0xffff;
		*(descript_addr+1) = (unsigned short) ((int) (*frame_addr) & 0xffff);
		*(descript_addr+2) = (unsigned short) ((int) (*frame_addr) >> 16);
		*(descript_addr+3) = config_word;
		frame_addr += 1;
		descript_addr = descript_addr+DESCRIPTOR_SIZE;
	}
	
	*descript_addr = (unsigned short) ((int)(descript_addr)-(int)(descript_size_in_bytes)*(int)(NUM_BUFFERS-1)) & 0xffff;
	*(descript_addr+1) = (unsigned short) ((int) (*frame_addr) & 0xffff);
	*(descript_addr+2) = (unsigned short) ((int) (*frame_addr) >> 16);
	*(descript_addr+3) = config_word & 0xffff;	//0x00ff to stop.  0xffff to loop.

	config_word &= 0xfffe;
	*pDMA1_0_CONFIG = config_word;
	ssync();		
}