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Visitor esi2st
Visitor
419 Views
Registered: ‎11-14-2018

Burst access with longer data types vs shorter data types

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Hi,

 

I am doing a project where I am reading and writing to DRAM (MIG) through a master axi interface. My data types are 16 bits wide. I am using a wide bus interface (128 bits wide)

 

My question is: Is the bus width efficiently utilized for a high burst access (128bit x 256 read/write) or is it confined by my data type (16bits x 256 read/write) if I use memcpy to copy 256x(128/16) values (corresponding to 128 bits x 256 read/write) from my data buffer? or do I have to pack up my data in 128 bit ap_uint types?

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Moderator
Moderator
320 Views
Registered: ‎10-04-2011

Re: Burst access with longer data types vs shorter data types

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Hello @esi2st,

 

Unfortunately, with HLS, you have to have the ports match what you would be connecting to. In this case, the 128-bit interface to the MIG/DDR IP. So yes, you would have to concatenate the 8 16-bit words into the single 128-bit interface. Else, as you mentioned, the efficiency of interface would be low with only 16 bits being used. 

 

OK, hope this helps,
Scott 

1 Reply
Moderator
Moderator
321 Views
Registered: ‎10-04-2011

Re: Burst access with longer data types vs shorter data types

Jump to solution

Hello @esi2st,

 

Unfortunately, with HLS, you have to have the ports match what you would be connecting to. In this case, the 128-bit interface to the MIG/DDR IP. So yes, you would have to concatenate the 8 16-bit words into the single 128-bit interface. Else, as you mentioned, the efficiency of interface would be low with only 16 bits being used. 

 

OK, hope this helps,
Scott