i2c passthru bridge from rpi to tuner

[trilby-hat-fpga] / i2c_bridge.v

diff --git a/i2c_bridge.v b/i2c_bridge.v
new file mode 100644 (file)
index 0000000..643bce9
--- /dev/null
+++ b/i2c_bridge.v
@@ -0,0 +1,44 @@
+`default_nettype none
+module i2c_bridge
+(
+    input  wire       clk,    // any
+    input  wire       clk_en, // 1-clk pulse, repeats 1.5-6 MHz
+    input  wire [1:0] i,      // inputs
+    output wire [1:0] t       // tristate 0->0 1->Z
+);
+  reg [1:0] state, next_state;
+
+  always @(posedge clk)
+    case(state)
+      2'd0: begin
+        if(i[0])
+          next_state <= 3;
+        else
+          next_state <= 0;
+      end
+
+      2'd1: begin
+        if(i[1])
+          next_state <= 3;
+        else
+          next_state <= 1;
+      end
+
+      default: begin
+        if(i[0]==0 && i[1]==1)
+          next_state <= 0;
+        else if(i[1]==0 && i[0]==1)
+          next_state <= 1;
+        else
+          next_state <= 3;
+      end
+    endcase
+
+  always @(posedge clk)
+    if(clk_en)
+      state <= next_state;
+
+  assign t[1] = state == 2'd0 ? 0:1;
+  assign t[0] = state == 2'd1 ? 0:1;
+
+endmodule