From 75ef4ad594b10a9c6af6f71a576ffb76e4c7a482 Mon Sep 17 00:00:00 2001
From: saji <saji@saji.dev>
Date: Mon, 29 Apr 2024 01:16:36 -0500
Subject: [PATCH] bram stuff

---
 verilog/hub75e.sv       | 42 ++++++++++++++++++++++++++--------------
 verilog/lineram.v       | 28 +++++++++++++++++++++++++++
 verilog/tb/hub75e_tb.sv | 43 ++++++++++++++++++++++++++++++++++-------
 3 files changed, 92 insertions(+), 21 deletions(-)
 create mode 100644 verilog/lineram.v

diff --git a/verilog/hub75e.sv b/verilog/hub75e.sv
index 49b865c..46eefb4 100644
--- a/verilog/hub75e.sv
+++ b/verilog/hub75e.sv
@@ -1,14 +1,17 @@
 module hub75e (
     input clk,
     input write_trig,
-    input [1:0][BIT_DEPTH - 1:0] rgb_row[ROW_DEPTH],
     output reg [4:0] addr,
     output reg [2:0] panel_rgb0,
     output reg [2:0] panel_rgb1,
     output reg display_clk = 0,
     output reg out_enable = 1,
     output reg latch = 0,
-    output reg done = 0
+    output reg done = 0,
+
+    // bram interface (using clk)
+    output reg [8:0] pixbuf_addr,
+    input [35:0] pixbuf_data
 );
 
   parameter integer ROW_DEPTH = 128, BIT_DEPTH = 8;
@@ -27,8 +30,6 @@ module hub75e (
 
 
   assign addr = 5'b10101;
-  assign panel_rgb0 = 3'b101;
-  assign panel_rgb1 = 3'b010;
 
   // initial begin
   //   state <= StateInit;
@@ -55,11 +56,12 @@ module hub75e (
     counter <= counter + 1;
     case (state)
       StateInit: begin
+        bcm_shift <= 7;
+        counter <= 0;
+        done <= 0;
+        pixbuf_addr <= 0;
         // wait for the signal to write out our lines.
         if (write_trig) begin
-          bcm_shift <= 7;
-          counter <= 0;
-          done <= 0;
           state <= StateWriteRow;
         end
       end
@@ -68,20 +70,31 @@ module hub75e (
         if (should_clock) begin
           // we have data to  clock
           display_clk <= counter[0];
-          if (counter[0]) begin
-            // load the next pixel data. this is the falling edge since the
-            // previous value is 1.
+          if (~counter[0]) begin
+            // the data from the previous cycle is now ready.
+            panel_rgb0 <= {
+              (pixbuf_data[bcm_shift]),
+              (pixbuf_data[bcm_shift + 8]),
+              (pixbuf_data[bcm_shift + 16])
+            };
+            panel_rgb1 <= {
+              (pixbuf_data[bcm_shift]),
+              (pixbuf_data[bcm_shift + 8]),
+              (pixbuf_data[bcm_shift + 16])
+            };
+            // write it out!
+          end else begin
+            // update the bram address so it's ready at the next clock cycle.
+            pixbuf_addr <= pixbuf_addr + 1;
           end
         end
         if (should_expose) begin
-          // we are still in our expose state, and our bcm shift is not the
-          // first one, so we should expose.
           out_enable <= 0;
         end else begin
           out_enable <= 1;
         end
         // if we're done with our data clock out and also done with exposing
-        // the previous frame, go next.
+        // the previous line, go to the latchout stage.
         if (~should_clock && ~should_expose) begin
           counter <= 0;
           state   <= StateLatchout;
@@ -92,10 +105,11 @@ module hub75e (
         // raise latch high; compute next bcm.
         latch <= 1;
         out_enable <= 1;
+        pixbuf_addr <= 0;
         counter <= counter + 1;
         if (counter > 3) begin
           if (bcm_shift == 0) begin
-            // done with the line. do the last (short) expose
+            // we've reached the lsb of this data, go to the next one!
             state <= StateFinishExpose;
             latch <= 0;
           end else begin
diff --git a/verilog/lineram.v b/verilog/lineram.v
new file mode 100644
index 0000000..564b4ed
--- /dev/null
+++ b/verilog/lineram.v
@@ -0,0 +1,28 @@
+module lineram #(
+    parameter DATA_WIDTH = 36,
+    parameter ADDR_WIDTH = 9
+) (
+    input [DATA_WIDTH - 1:0] din,
+    input [ADDR_WIDTH - 1:0] addr_w,
+    output reg [DATA_WIDTH - 1:0] dout,
+    input [ADDR_WIDTH - 1:0] addr_r,
+    input write_en,
+    input read_clk,
+    input write_clk
+);
+
+  reg [DATA_WIDTH - 1] ram[2**ADDR_WIDTH];
+
+  initial begin
+    for(int i=0; i < 2**ADDR_WIDTH; i=i+1) begin
+      ram[i] = 0;
+    end
+  end
+
+  always @(posedge write_clk) begin
+    if (write_en) ram[addr_w] <= din;
+  end
+  always @(posedge read_clk) begin
+    dout <= ram[addr_r];
+  end
+endmodule
diff --git a/verilog/tb/hub75e_tb.sv b/verilog/tb/hub75e_tb.sv
index 146f6d5..ae6dc2e 100644
--- a/verilog/tb/hub75e_tb.sv
+++ b/verilog/tb/hub75e_tb.sv
@@ -4,8 +4,6 @@ module hub75e_tb;
   reg clk;
   reg write_trig;
 
-  reg [1:0][7:0] rgb_row[128];
-
   wire [4:0] addr_out;
   wire [2:0] rgb0;
   wire [2:0] rgb1;
@@ -15,27 +13,58 @@ module hub75e_tb;
   wire done;
 
 
+  // block ram inputs
+  reg [35:0] bram_data_in;
+  reg [8:0] bram_addr_w;
+  reg bram_write_en;
+
+
+  wire [8:0] bram_addr_r;
+  wire [35:0] bram_data_out;
+
+
+  lineram bram (
+    .din(bram_data_in),
+    .addr_w(bram_addr_w),
+    .dout(bram_data_out),
+    .addr_r(bram_addr_r),
+    .write_en(bram_write_en),
+    .read_clk(clk),
+    .write_clk(clk)
+  );
+
   hub75e dut (
       .clk(clk),
       .write_trig(write_trig),
-      .rgb_row(rgb_row),
       .addr(addr_out),
       .panel_rgb0(rgb0),
       .panel_rgb1(rgb1),
       .display_clk(display_clk),
       .out_enable(out_enable),
       .latch(latch),
-      .done(done)
+      .done(done),
+
+      .pixbuf_addr(bram_addr_r),
+      .pixbuf_data(bram_data_out)
   );
 
   always #5 clk = !clk;
   initial begin
     $dumpfile("wave.vcd");
     $dumpvars(0, hub75e_tb);
-    clk = 0;
-    write_trig = 1;
+    clk <= 0;
+    bram_addr_w <= 0;
+    bram_write_en <= 1;
+    repeat (1) @(posedge clk);
+    for (int i=0; i < 128; i=i+1) begin
+      bram_data_in <= $urandom % 'hFFFFFF;
+      bram_addr_w <= i;
+      repeat (1) @(posedge clk);
+    end
+    bram_write_en <= 1;
+    write_trig <= 1;
     repeat (2) @(posedge clk);
-    write_trig = 0;
+    write_trig <= 0;
 
     @(done);
     repeat (20) @(posedge clk);