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

[Altera_Forum]

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!!!

[Altera_Forum]

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]

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