Initial commit.

1 files changed, 93 insertions, 0 deletions

diff --git a/piodev1.v b/piodev1.v
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+module piodev1(
+    input nIN_CH,
+    output nCS_CH,
+
+    inout [0:7] D,
+
+    output A20_SRAM,
+    output nCS_SRAM,
+
+    input nRD,
+    input nWR,
+
+    input CLK,
+
+    output nCS_SW,
+    output WR_LEDS,
+
+    input SWRESET,
+    input RECOVERY,
+
+    output nIN10,
+    input nCS0,
+    input nCS2,
+    output SBEN,
+
+    inout [0:7] PD,
+
+    input A0,
+    input A1,
+    input A2,
+    input A3,
+    input A20,
+    input A21,
+    input A22,
+
+    output A20_FLASH,
+    output nCS_FLASH,
+
+    output nCS_PORTA,
+    output nCS_PORTB,
+    output A0_PORTA,
+    output nRST_FT,
+
+    input NRST
+    );
+
+wire CS0 = !nCS0;
+wire CS2 = !nCS2;
+
+wire CS_FLASH = CS2;
+wire CS_PORTA = CS0;
+
+assign nCS_FLASH = !CS_FLASH;
+assign nCS_PORTA = !CS_PORTA;
+
+assign SBEN = 1'b1;
+
+assign A20_FLASH = A20;
+
+assign A0_PORTA = 1'b0;
+
+assign nCS_PORTB = 1'b1;
+assign nRST_FT = 1'b1;
+
+reg PDtoD = 1'b0;
+reg [7:0] buffer = 0;
+
+wire activateOutput = CS0 | CS2;
+
+always @(negedge nWR or negedge nRD) begin
+  if (!nWR) begin
+    PDtoD <= 1'b0;
+  end
+
+  if (!nRD) begin
+    PDtoD <= 1'b1;
+  end
+end
+
+always @(posedge nWR or posedge nRD) begin
+  if (nWR) begin
+    buffer <= D;
+  end
+
+  if (nRD) begin
+    buffer <= PD;
+  end
+end
+
+assign D = (PDtoD && activateOutput) ? buffer : 8'bzzzzzzzz;
+assign PD = !PDtoD ? buffer : 8'bzzzzzzzz;
+
+endmodule