MPC5644A - eDMA Trial

ShadowShooTR — Wed, 17 Feb 2021 09:37:09 GMT

Hi all,

I just want to transfer data from source to destination like ;

Source : uint8 g_uchSource[12] --> the address is 0x40001e80

Source variables are : 0x00 , 0x11 , 0x22 , 0x33, 0x44 , 0x55, 0x66 , 0x77, 0x88, 0x99, 0xAA , 0xBB

Destination : uint16 g_untGhostHold[6]. --> the address is 0x40001e8c

The DMA TCD is arranged as :

EDMA.TCD[CH2].SADDR = (vuint32)&g_uchSource;
EDMA.TCD[CH2].DADDR = (vuint32)&g_untGhostHold;
EDMA.TCD[CH2].CITER = (vuint16)3;
EDMA.TCD[CH2].BITER = (vuint16)3;
EDMA.TCD[CH2].SSIZE = 0; //8 bit source size
EDMA.TCD[CH2].DSIZE = 1; //16 bit destination size
EDMA.TCD[CH2].NBYTES = 4; //4 bytes will be transferred for each major iteration
EDMA.TCD[CH2].SLAST = (vuint32)(-1*12); //return
EDMA.TCD[CH2].CITERE_LINK = 0;
EDMA.TCD[CH2].BITERE_LINK = 0;
EDMA.TCD[CH2].BWC = 0;
EDMA.TCD[CH2].DLAST_SGA = (vuint32)(-2*6); //return
EDMA.TCD[CH2].SMOD = 0;
EDMA.TCD[CH2].DMOD = 0;
EDMA.TCD[CH2].SOFF = 1; //Source minor address iteration will be 1 byte
EDMA.TCD[CH2].DOFF = 2; //Destination 2 byte
EDMA.TCD[CH2].MAJORE_LINK = 0;
EDMA.TCD[CH2].MAJORLINKCH = 0;
EDMA.TCD[CH2].E_SG = 0;
EDMA.TCD[CH2].D_REQ = 0;
EDMA.TCD[CH2].INT_HALF = 0;
EDMA.TCD[CH2].INT_MAJ = 0;
EDMA.TCD[CH2].ACTIVE = 0;
EDMA.TCD[CH2].DONE = 0;
EDMA.TCD[CH2].START = 0;

Then I set the TCD.START bit in the software.

I expected that it would work like this :

1. Major (CITER = 3)

- 1.Minor -> read(0x40001e80) , read(0x40001e81)

write(0x40001e8c)

- 2.Minor -> read(0x40001e82) , read (0x40001e83)

write(0x40001e8e)

2. Major (CITER = 2)

- 1.Minor -> read(0x40001e84) , read(0x40001e85)

write(0x40001e90)

- 2. Minor -> read(0x40001e86) , read(0x40001e87)

write(0x40001e92)

3. Major (CITER = 1)

- 1. Minor -> read(0x40001e88), read(0x40001e89)

write(0x40001e94)

- 2. Minor -> read(0x40001e8A), read(0x40001e8B)

write(0x40001e96)

Then Majors are complete, TCD.DONE will be set.

However it didn't work as I expected.

In experiment :

After the first major iteration ,DMA stops. CITER decreased just once and 4 byte transfer occured as shown below.

Then I set the TCD_START bit manually.

Then other 4 byte transferred correctly. CITER decreased again.

Again, I set TCD_Start bit manually , The TCD_DONE bit is set at this time.

All transfers were done correctly by setting TCD_START bit manually for every major iteration break, but the question is that why doesn't DMA continue to work by itself after the first major iteration done until TCD_DONE occurs ?

I searched referance manual (Page 589), it's given a similar example but it is hardware request.

There is a sentence like this :

Probably , eDMA goes idle in my case right ?

I do this transfer with single request just setting CITER = 1 and NBYTE = 12. It works.

I tried different channel but no change.

Do I have to do this transfer with hardware request ? But it's not any specific signal or module.

Thank you in advance.

Best regards.

SS.

Re: MPC5644A - eDMA Trial

davidtosenovjan — Wed, 17 Feb 2021 11:10:10 GMT

Hi, it is correct behavior. Every time CITER is decreased, new DMA request is needed. DMA request means either HW request from other module or assertion of START bit by SW.

Re: MPC5644A - eDMA Trial

ShadowShooTR — Wed, 17 Feb 2021 12:22:45 GMT

Hi,

I thought that those minor requests will trigger by themselves until major complete. That was the hardware request. I missed this point. Thank you so much @davidtosenovjan.

Re: MPC5644A - eDMA Trial

berat24 — Thu, 26 Aug 2021 11:04:48 GMT

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