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DMA transfer count

Question asked by Andrei Chichak on Feb 27, 2017

Since the Wish List seems to be closed, I'll put this request here.


To the processor designers:


The DMA transfer count is a 16 bit value that can be in the range 1-65535. Since 0 is a useless value and 65536 would be a useful value, could you change the hardware so that we can specify the count to be 1-65536?


You see, program FLASH on the 407 is 1MB, or 256K words. If I could specify a count of 65536, I could CRC all of program FLASH in exactly 4 transfers. 


But since the maximum is 65535, I have to either do 5 weird sized DMAs to the CRC unit, or go for 8 transfers of 32768 words each.


Just a thought.


Andrei from The Great White North

as seen on the Embedded.FM embedded systems podcast and blog.