Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

The sgdma in sopc has 8 bits per symbol?

Hi,I developed a component with a streaming soure interface whose data width is 32 bits(per symbol),but when I add this componet to a sopc system which also instantiatized a sgdma component,and the s...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

The symbol size of the SGDMA is the same width as a byte. Avalon-MM is 'little endian' whereas ST is 'big endian' so when the transfer occurs between MM and ST the symbols are flipped. So the tools are just telling you that the SGDMA streaming port has a different unit of data (symbol) than the streaming port connected to it. So this symbol size is independent of the data width, by adjusting the width of the SGDMA you are just increasing/decreasing the number of symbols per beat. If you take a look at the Avalon spec this should become clear.

To work around this you can make a simple ST widget that has 8-bit symbols on one side and wide symbols on the other and wire the data through between the two ports.