ppi0_init.c

基于visual dsp++开发环境

#include "main.h"

/********************************************************************************/
/***** InitPPI0()															*****/
/***** PPI0 is configured in infinite capture, self triggered mode			*****/
/***** This routine configures both the PPI and the associated DMA channel	*****/
/***** Supports  16 and 32 bit DMA according to the input parameter 		*****/
/***** DMA is setup in descriptor list mode, input is pointer to 1st header	*****/
/********************************************************************************/

void InitPPI0(bool dma32, tDMA_descriptor* First_Header, short lower, short upper)
{ short transfer_length_bytes = ((dma32) ? 4 : 1);

	// configure PPI0 - not enabled yet
	*pPPI0_CONTROL = 0x3800 | FLD_SEL | (dma32 << 8) | PORT_CFG | XFR_TYPE;
	*pPPI0_FRAME = upper;
	ssync();

	// configure DMA for PPI0 - not enabled yet
	*pDMA1_0_X_COUNT = lower * sizeof(short) / transfer_length_bytes;	// 2 bytes for each sample, count divided by four if 32-bit DMA transfers are done
	*pDMA1_0_Y_COUNT = upper;
	*pDMA1_0_X_MODIFY = transfer_length_bytes;		
	*pDMA1_0_Y_MODIFY = transfer_length_bytes;		
	*pDMA1_0_NEXT_DESC_PTR = First_Header;
	*pDMA1_0_CONFIG = 0x7000 | 0x0400 | DI_EN | DMA2D | (dma32 << 3) | WNR;
	
	ssync();
	
}