TMS570LS3137: DMA Addressing Mode is not working

Faruk Keser

Prodigy 20 points

Part Number: TMS570LS3137

Hi,

I wrote a program that using ADC with DMA.

If i code like that it didnt work correctly.

************************************************************

g_dmaCTRL g_dmaCTRL_init;

///

g_dmaCTRL_init.ELDOFFSET = 0;

g_dmaCTRL_init.ELSOFFSET = 0;

g_dmaCTRL_init.FRDOFFSET = 0;

g_dmaCTRL_init.FRSOFFSET = 0;

g_dmaCTRL_init.ADDMODERD = ADDR_INC1;

g_dmaCTRL_init.ADDMODEWR = ADDR_FIXED;

///

************************************************************

but if i code like that it worked correctly.

************************************************************

g_dmaCTRL g_dmaCTRL_init;

///

g_dmaCTRL_init.ELDOFFSET = 0;

g_dmaCTRL_init.ELSOFFSET = 1;

g_dmaCTRL_init.FRDOFFSET = 0;

g_dmaCTRL_init.FRSOFFSET = 1;

g_dmaCTRL_init.ADDMODERD = ADDR_OFFSET;

g_dmaCTRL_init.ADDMODEWR = ADDR_OFFSET;

///

************************************************************

i couldnt get it why.

Thanks,

over 3 years ago

0 jagadish gundavarapu over 3 years ago

TI__Guru 71411 points

Hi Faruk,

I guess in your first case you are doing wrong because here we are using DMA to the ADC, so we have to read the converted value from ADC and have to write it to the buffer. Reading is from ADC and writing is to Buffer, so read address should be fixed(because it is ADC register) and write address should be incremented(because it is buffer), but you are doing this in reverse way. So that might be the reason for your failure.