EDMA 自链接

zc wang

请问，

EDMA在发送初始化和发送完成中断中，都会用到的这个函数设置为自链接，是什么作用？

/*
** Assigns loop job for a parameter set
*/
static void ParamTxLoopJobSet(unsigned short parId)
{
EDMA3CCPaRAMEntry paramSet;

memcpy(&paramSet, &txDefaultPar, SIZE_PARAMSET - 2);

/* link the paRAM to itself */
paramSet.linkAddr = parId * SIZE_PARAMSET;

EDMA3SetPaRAM(SOC_EDMA30CC_0_REGS, parId, &paramSet);
}

9 年多前

0 zc wang 9 年多前

Intellectual 321 points

请教 @Tony Tang

还有个问题，每次启动发送前不需要判断下这个通道是否处于空闲状态吗？（官方mcsap-edma demo）

while(1)
{
if(lastFullRxBuf != lastSentTxBuf)
{
/*
** Start the transmission from the link paramset. The param set
** 1 will be linked to param set at PAR_TX_START. So do not
** update paRAM set1.
*/
parToSend = PAR_TX_START + (parOffTxToSend % NUM_PAR);
parOffTxToSend = (parOffTxToSend + 1) % NUM_PAR;
parToLink = PAR_TX_START + parOffTxToSend;

lastSentTxBuf = (lastSentTxBuf + 1) % NUM_BUF;

/* Copy the buffer */
memcpy((void *)txBufPtr[lastSentTxBuf],
(void *)rxBufPtr[lastFullRxBuf],
AUDIO_BUF_SIZE);

/*
** Send the buffer by setting the DMA params accordingly.
** Here the buffer to send and number of samples are passed as
** parameters. This is important, if only transmit section
** is to be used.
*/
BufferTxDMAActivate(lastSentTxBuf, NUM_SAMPLES_PER_AUDIO_BUF,
(unsigned short)parToSend,
(unsigned short)parToLink);
}
}