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CAlex's avatar
CAlex
Icon for Contributor rankContributor
2 years ago
Solved

Request of AXI bridge example for CycloneVsoc HPS to FPGA communication

Hi I've tried the AVALON MM bridge HPS to FPGA translating 32 bit data for each using alt_write_word() and alt_read_word(). There is ~2us latency between orders(128bit wide H2F bridge with 50MHZ cl...
Fpga Devkit
  • tehjingy_Altera's avatar
    tehjingy_Altera
    2 years ago

    Hi Alex


    The dword read is the maximum size that is available by the library to read through the bridge.

    Is reading using the dword improve the situation on your end?


    The difference between a normal and burst command is the in the burst command there are addtional signals such as ARBURST, ARSIZE ,RLAST.

    In the burst command it will have state the number of burst read from the receiver to send the data.

    https://docs.xilinx.com/r/en-US/ug1399-vitis-hls/AXI-Burst-Transfers


    Regards

    Jingyang, Teh





tehjingy_Altera's avatar
tehjingy_Altera
Icon for Regular Contributor rankRegular Contributor
2 years ago

Hi Alex


I would suggest you to try use the alt_read_dword to see if it is improving on your end.


For the bridges for the HPS to FPGA communication the bridges are already AXI.

However because the api of the alt_read uses word wise read and write over the bridges. It does not fully utilize the AXI feature of the burst and stream.


Regards

Jingyang, Teh




  • CAlex's avatar
    CAlex
    Icon for Contributor rankContributor
    2 years ago

    Hi，

    I'm not sure how to correctly use the burst and stream function of the H2F bridge.

    Now what I do is making a FPGA memory

    | | 32 bit read | | 128 bit wide | |
    | FPGA MEM [depth:0][width:0] S | ==============> |M AVA MM PIPELINE BRIDGE S| ==========> |M HPS H2F |
    | | 32 bit write | | | |

    If Im going to use burst transmit, other than changing the 32 bit R/W tunnel to 64 bit( if I'm going to use alt_write_dword ), what else should I do in FPGA & HPS Baremetal SOC?

    Do you have any examples on that?

    Thank you

    Reguards

    Alex