ppi1_init.c

This example streams input from a ADC source to a DAC. An analog signal is acquired block-by-block

#include "main.h"

/********************************************************************************/
/***** InitPPI1()															*****/
/***** PPI1 is configured for  GP output 1FS 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 InitPPI1(bool dma32, tDMA_descriptor* First_Header, short lower, short upper)
{ short transfer_length_bytes = ((dma32) ? 4 : 1);

	// configure Timer10 for PPI frame sync - not enabled yet
	*pTMRS4_DISABLE |= TIMDIS10;						//disable Timer
	*pTMRS4_STATUS |= (TIMIL10 | TOVL_ERR10 | TRUN10);	// clear status

	*pTIMER10_PERIOD = lower * sizeof(short);
	*pTIMER10_WIDTH = 0x10;		// some small dutycycle
	if ( (*pDSPID & 0x0000000F ) < 0x0002) 
	      *pTIMER10_CONFIG   = PWM_OUT | PULSE_HI | PERIOD_CNT | CLK_SEL | EMU_RUN;	// for revision <0.2 it will need to be written again after PPI is initialised and enabled
	  else
		  *pTIMER10_CONFIG   = TIN_SEL | PWM_OUT | PULSE_HI | PERIOD_CNT | CLK_SEL | EMU_RUN;	
	ssync();
	
	// configure PPI1 - not enabled yet
	*pPPI1_CONTROL = 0x3800 | PORT_DIR | XFR_TYPE |  (dma32 << 8);
	*pPPI1_COUNT = lower * sizeof(short);					// 2 bytes for each sample
	ssync();

	// configure DMA for PPI1 - not enabled yet
	*pDMA1_1_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_1_Y_COUNT = upper;
	*pDMA1_1_X_MODIFY = transfer_length_bytes;		
	*pDMA1_1_Y_MODIFY = transfer_length_bytes;		
	*pDMA1_1_NEXT_DESC_PTR = First_Header;
	*pDMA1_1_CONFIG = 0x7000 | 0x0400 | DI_EN | DMA2D | (dma32 << 3);
	
	ssync();
	
}