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Accessing DDR-Ram from FPGA on DE1-SoC

Honored Contributor II


I’m trying to write data directly to the HPS DDR3-RAM on my eval board. 

Problem is, I’m quite new to FPGAs in general and so after a bit of research I ended up with the following idea: 

I thought of use this: https://www.altera.com/support/support-resources/design-examples/intellectual-property/embedded/nios... 

Avalon MM Template to address the HPS (f2h_sdram0 Avalon-MM Write-Only 32) 

I wrote a Verilog file containing a state machine to fill the required registers of the template according to its manual. 

From what I see the master_crtl_done flag gets set, but I can’t see the written data. 


To test my data transfer I tried to write some data to the ram which can be seen from the Linux system running on the SoC, using memtool I wanted to see if there is a change. But it seems this doesn’t work (no changes in memory) 


Can someone tell me if this is a valid way to write to the memory or if my whole idea is wrong (as said I’m quite new to this only a few weeks in). 

Or if I just messed something up. 


Thanks in advance! 

module mem_access ( clk, reset_n, master_crtl_fixed_location, master_crtl_write_base, master_crtl_lenght, master_crtl_go, master_crtl_done, master_user_write_buffer, master_user_buffer_input_data, master_user_buffer_full, but0, led ); input wire clk; input wire reset_n; output wire master_crtl_fixed_location; output wire master_crtl_write_base; output wire master_crtl_lenght; output wire master_crtl_go; input wire master_crtl_done; output wire master_user_write_buffer; output wire master_user_buffer_input_data; input wire master_user_buffer_full; input wire but0; output wire led; parameter IDLE = 5'b00001, STATE1 = 5'b00010, STATE2 = 5'b00100, STATE3 = 5'b01000, STATE4 = 5'b10000; reg state_but = 1; reg state = IDLE; reg dataToWrite; reg writeBuffer; reg startWriting; reg led_int = 4'b0000; reg startAddress = 'h10000000; always @ (posedge clk) begin case(state) IDLE: begin if (but0 == 1 && but0 != state_but) state <= STATE1; //led_int = 4b'0000; if (led == 1) led_int <= 0; end STATE1: begin dataToWrite <= 13; state <= STATE2; led_int <= 1; end STATE2: begin if (master_user_buffer_full != 1) writeBuffer <= 1; else writeBuffer <= 0; state <= STATE3; led_int <= 1; end STATE3: begin startWriting <= 1; //writeBuffer <= 0; state = STATE4; led_int <= 1; end STATE4: begin startWriting <= 0; if (master_crtl_done == 1) begin state = IDLE; startAddress <= startAddress + 1; end led_int <= 1; end endcase state_but = but0; end assign master_crtl_fixed_location = 0; assign master_crtl_write_base = startAddress; assign master_crtl_lenght = 4; assign master_user_buffer_input_data = dataToWrite; assign master_user_write_buffer = writeBuffer; assign master_crtl_go = startWriting; assign led = led_int; endmodule
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2 Replies
Honored Contributor II

You should put some signaltap probes around your Avalon master to see what it is doing and what it is writing, to what address. 

Also on the software side, remember to invalidate the data cache before attempting to read the memory back, or the CPU will just read from its cache instead of the SDRAM.
Honored Contributor II

Hi cyano Im working in a project and I need too to write data to HPS DDR3 .I found an exemple to whrite in DDR3 memory https://support.criticallink.com/redmine/projects/mityarm-5cs/wiki/writing_to_hps_memory my problem when i type the command memtool on putty terminal it returns command not found ,should I install some software package to run this command ?? I try to install some packages but the command apt get gives also command not found.Pllz need your help im newbie in linux and putty terminal......