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Altera_Forum
Honored Contributor I
802 Views

how to calculate the length register and the burst count port in DMA control manual

hello: 

when I read the DMA control manual provided by the altera.com,I came across a question. 

According to the manual at page 3 "The master Read and Write port",it says "For example, if a 32-bit data width DMA is programmed for a word transfer of 64 bytes, the length registered is programmed with 64 and the burst count port will be 16. If a 64-bit data width DMA is programmed for a doubleword transfer of 8 bytes, the length register is programmed with 8 and the burst count port will be 1." 

I can't understand the meaning of the above paragraph,can anyone help me?
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2 Replies
Altera_Forum
Honored Contributor I
37 Views

Length register == number of bytes. 

Burst count == number of transfers of full bus width. 

 

64 bytes (512 bits) on 32 bit bus: 512/32 = burst count of 16. 

8 byte (64 bits) on 64 bit bus: 64/64 = burst count of 1.
Altera_Forum
Honored Contributor I
37 Views

 

--- Quote Start ---  

Length register == number of bytes. 

Burst count == number of transfers of full bus width. 

 

64 bytes (512 bits) on 32 bit bus: 512/32 = burst count of 16. 

8 byte (64 bits) on 64 bit bus: 64/64 = burst count of 1. 

--- Quote End ---  

 

Matthias Wachter: 

thank you very much,best wishes!