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  1. I'm at a complete loss trying to get the Arty A7-100t onboard DDR-SDRAM to behave reliably. Let me start by telling you what I've done (maybe some of this will be helpful for others): The Arty A7-100t is running totally unmodified (no PMOD, ChipKit, etc.). I've generated a Memory Interface Generator (MIG) IP core as per Digilent's recommendations: Digilent MIG Resources My XCI and PRJ files: ddr_sdram_mig.xci and ddr_sdram_mig.prj I've written a simple DDR SDRAM Interface module, based on the approach found on Numato. Unlike the reference code, my Verilog reads incoming addresses and reads / writes to RAM (or at least it should): ddr-sdram-interface.v I continually read from the aforementioned memory interface via the following code: always @(posedge clk_100mhz) begin if (readReady) begin readAddr <= readAddr + 1; end end assign led = readData[7:0]; I write to the memory (first all zeros, then all ones, then the address) via the following code: always @(posedge clk_100mhz) begin if (writeReady) begin writeAddr <= writeAddr + 1; if ((writeAddr == 0) && (writeCounter < 3)) begin writeCounter <= writeCounter + 1; end case (writeCounter) 0: writeData <= 32'h00000000; 1: writeData <= 32'h11111111; 2: writeData <= {8'h00, writeAddr}; 3: writeEn <= 0; endcase end end Now for the problem: If I run the Verilog above exactly as-is, the LEDs show total garbage (randomness). If, instead, I continually write (the same) data to memory over-and-over again, eventually the LEDs will start flashing the binary counter I expect. This tells me that the read mechanism is functional, but the write is extremely unreliable. Any insight would be most appreciated. I purchased the Arty A7-100t in part because it has the DDR3 memory. I understand that there are significant performance issues (due to the -1 speed grade of the Artix-7 chip), but I expect to be able to attain reliable read / write behavior at low-speed.
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