12-20-2010 03:12 AM
hello,Now I'm using stratix iv 230 device in a project.I use qdr_sram_compiler_with_uniphy as my qdr2 chip controller.The software is quartus ii 10.0 sp1.All the docs downloaded from the web do not describe the avl_w_size signal.I have been in this trouble so long,need help!
12-24-2010 02:26 PM
hi,std_logic.At the first sight of your name,i see the you are expert on VHDL.Yes?Haha,just a joke. Based on several experiments,I have summarized the usage of avl_w_write_size.Max_burst_length affects the width of avl_w_write_size(also avl_read_size),Nwidth = (log 2 (max_burst_length))+1.What is burst length?Cycpress's qdrii chip generally has 2 or 4 mem array,ie the data width of the chip is 9,addr width is 21.There 2 or 4 mem array with 21 addr width and 9 data width.If the burst_length is 2,then the avl_write_data and avl_read_data is 18,or if the burst_length is 4,then the avl_write_data and avl_read_data is 36.Here burst_length is not the same as max_burst_length. What is the usage of "size"?For example,we set max_burst_length is 8.Then the width of "size" is 4.If we set "size"="0001",when read and write,we should increase the address by a0;if we set "0010",we should increase the address by a1;if we set "0100",we should increase the address by a2;if we set "1000",we should increase the address by a3.A3,pay attention to it,burst = 8 words. All above is summarized by experiments,docs about the new ip is like noting.I have consulted to altera FAE,but they do not kown it very well.Hope docs released!!
12-27-2010 05:54 PM
Burst length is number of accesses per command.Take DDR3 which is nominally BL=8 on the memory interface. If using half rate I need to provide 2 beats of data to get the entire 8 beats on the memory interface. If I do this on consecutive clock edges I can set local_size = 2 and set burstbegin high on the first one. Or if the data is not ready on consecutive clock cycles I can use local size = 1 and push the first beat in, wait and do the same again for the 2nd beat, each time setting burstbegin high.