Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

how to access the on-chip fifo with my logic module for ST interface

I add a on-chip fifo in Qsys(see the attached figure),

one interface is Avalon MM for nios2 access,and another interface is ST source

for my logic .

and the ST source's signals :

fifo_data_clk_out_clk : in std_logic := 'X'; -- clk

fifo_data_out_valid : out std_logic; -- valid

fifo_data_out_data : out std_logic_vector(31 downto 0); -- data

fifo_data_out_ready : in std_logic := 'X' -- ready

in my logic,how to access the ST source? how to use the valid and ready signal?

1, ST sink(my logic) give the ready,after when valid is assert,and the data is active?

2,other usages?

thanks for your help!!!

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    I have tested the on-chip fifo ,with avalon mm write port and st read port

    when I assert the ready high for st read port,the write data to avalon mm port

    will go through the st port, and the valid signal keep low(I use it to trigger a

    vhdl module with its rising edge,but not active ),why?

    thanks for your help!
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    I think I find out the issue:

    module subfifo_fifo_0 (

    // inputs:

    avalonmm_write_slave_address,

    avalonmm_write_slave_write,

    avalonmm_write_slave_writedata,

    avalonst_source_ready,

    rdclock,

    rdreset_n,

    wrclock,

    wrreset_n,

    // outputs:

    avalonmm_write_slave_waitrequest,

    avalonst_source_data,

    avalonst_source_valid

    )

    ;

    output avalonmm_write_slave_waitrequest;

    output [ 31: 0] avalonst_source_data;

    output avalonst_source_valid;

    input avalonmm_write_slave_address;

    input avalonmm_write_slave_write;

    input [ 31: 0] avalonmm_write_slave_writedata;

    input avalonst_source_ready;

    input rdclock;

    input rdreset_n;

    input wrclock;

    input wrreset_n;

    wire [ 31: 0] avalonmm_map_data_in;

    wire avalonmm_write_slave_waitrequest;

    wire [ 31: 0] avalonst_map_data_out;

    wire [ 31: 0] avalonst_source_data;

    reg avalonst_source_valid;

    wire [ 31: 0] data;

    wire [ 31: 0] q;

    wire rdclk;

    wire rdempty;

    wire rdreq;

    wire wrclk;

    wire wrfull;

    wire wrreq;

    wire wrreq_driver;

    //the_dcfifo_with_controls, which is an e_instance

    subfifo_fifo_0_dcfifo_with_controls the_dcfifo_with_controls

    (

    .data (data),

    .q (q),

    .rdclk (rdclk),

    .rdempty (rdempty),

    .rdreq (rdreq),

    .wrclk (wrclk),

    .wrfull (wrfull),

    .wrreq (wrreq),

    .wrreset_n (wrreset_n)

    );

    //in, which is an e_avalon_slave

    assign avalonmm_write_slave_waitrequest = wrfull;

    //the_map_avalonmm_to_avalonst, which is an e_instance

    subfifo_fifo_0_map_avalonmm_to_avalonst the_map_avalonmm_to_avalonst

    (

    .avalonmm_data (avalonmm_map_data_in),

    .avalonst_data (avalonst_map_data_out)

    );

    assign wrreq_driver = (avalonmm_write_slave_address == 0) & avalonmm_write_slave_write;

    assign avalonmm_map_data_in = avalonmm_write_slave_writedata;

    assign wrreq = wrreq_driver;

    assign data = avalonst_map_data_out;

    assign wrclk = wrclock;

    assign rdclk = rdclock;

    assign avalonst_source_data = q;

    assign rdreq = !rdempty & avalonst_source_ready;

    always @(posedge rdclk or negedge rdreset_n)

    begin

    if (rdreset_n == 0)

    avalonst_source_valid <= 0;

    else

    avalonst_source_valid <= !rdempty & avalonst_source_ready;

    end

    //out, which is an e_atlantic_master

    endmodule