DMA With minor loops

davidzhou — Wed, 11 May 2016 21:11:57 GMT

Hi,

I have K60 Tower board: TWRK60F120MUM

I have DMA transfer 2 bytes for each external trigger (from PORT B input)

ChnInit1.TCD.DMA_TCD_SADDR_Reg = DMA_SADDR_SADDR((void*)&FTM1_CNT) ;

ChnInit1.TCD.DMA_TCD_SOFF_Reg = 0x0; //Source address increment: no increment needed

ChnInit1.TCD.DMA_TCD_SLAST_Reg = 0; //Source address reload after major loop finishes: no reload needed

ChnInit1.TCD.DMA_TCD_ATTR_Reg = DMA_ATTR_SSIZE(1) | DMA_ATTR_DSIZE(1) ;

// destination configuration

ChnInit1.TCD.DMA_TCD_DADDR_Reg = DMA_DADDR_DADDR((void*)UserDataPtr);//&gdwDummyDA

ChnInit1.TCD.DMA_TCD_DOFF_Reg = 0x0;

ChnInit1.TCD.DMA_TCD_DLASTSGA_Reg = 0; //in Bytes : reload after major loop finishes

// set CITER and BITER to maximum value

ChnInit1.TCD.DMA_TCD_BITER_Reg = DMA_BITER_ELINKNO_BITER_MASK;

ChnInit1.TCD.DMA_TCD_CITER_Reg = DMA_CITER_ELINKNO_CITER_MASK;

ChnInit1.TCD.DMA_TCD_NBYTES_Reg = 2;

// enable auto close request

ChnInit1.TCD.DMA_TCD_CSR_Reg = 0; //disale ELINK

// ChnInit1.TCD.DMA_TCD_CSR_Reg |= DMA_CSR_DREQ_MASK;

It works.

But I want to transfer 8 bytes for each trigger, changed CNT to SC. and I make the following modifications:

ChnInit1.TCD.DMA_TCD_SADDR_Reg = DMA_SADDR_SADDR((void*)&FTM1_SC) ;

ChnInit1.TCD.DMA_TCD_SOFF_Reg = 0x4; //Source address increment: no increment needed

ChnInit1.TCD.DMA_TCD_SLAST_Reg = 0; //Source address reload after major loop finishes: no reload needed

ChnInit1.TCD.DMA_TCD_ATTR_Reg = DMA_ATTR_SSIZE(2) | DMA_ATTR_DSIZE(2) | DMA_ATTR_DMOD(8) | DMA_ATTR_SMOD(8) ;

// destination configuration

ChnInit1.TCD.DMA_TCD_DADDR_Reg = DMA_DADDR_DADDR((void*)UserDataPtr);//&gdwDummyDA

ChnInit1.TCD.DMA_TCD_DOFF_Reg = 0x4;

ChnInit1.TCD.DMA_TCD_DLASTSGA_Reg = 0; //in Bytes : reload after major loop finishes

// set CITER and BITER to maximum value

ChnInit1.TCD.DMA_TCD_BITER_Reg = DMA_BITER_ELINKNO_BITER_MASK;

ChnInit1.TCD.DMA_TCD_CITER_Reg = DMA_CITER_ELINKNO_CITER_MASK;

ChnInit1.TCD.DMA_TCD_NBYTES_Reg = 8;

// enable auto close request

ChnInit1.TCD.DMA_TCD_CSR_Reg = 0; //disale ELINK

// ChnInit1.TCD.DMA_TCD_CSR_Reg |= DMA_CSR_DREQ_MASK;

It only transfer once (8 Bytes). It doesn't continuously transfer with each trigger.

Suppose NBYTES=8 is minor loop. Why it only transfer once (8 bytes)?

Thank you,

david Zhou

Re: DMA With minor loops

Hui_Ma — Thu, 12 May 2016 06:34:20 GMT

It need to set ChnInit1.TCD.DMA_TCD_NBYTES_Reg value to you expected total transfer bytes, such as 0x400 (1KBytes).

Wish it helps.

Have a great day,
Ma Hui
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