|ARM Technical Support Knowledge Articles|
Applies to: PL08x DMAC (DM & SM)
DBSize/SBSize is the amount of data transferred when the DMACxBREQ signal goes active. The value of HBURST depends on DBSize/SBSize and DWidth/SWidth. Since the FIFO is only four words deep, an INCR4 is the maximum HBURST possible when transferring words. When transferring half-words (16 bit quantities), INCR8 is the maximum HBURST size possible; with BYTES it is INCR16. Let's say that PL081 is told to transfer 15 words. Assuming the initial conditions of DBSize = SBSize = 4, DWidth = SWidth = WORD, it will transfer this burst as 3 x HBURST = INCR4, followed by 3 x HBURST = INCR where the burst length is one.
Did you find this article helpful? Yes No
How can we improve this article?