attach a 16 bit device to the bus and make it look like a 32 bit device

git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@9635 221aa14e-8319-0410-a670-987f0aec2ac5

diff --git a/usrp2/fpga/control_lib/wb_bridge_16_32.v b/usrp2/fpga/control_lib/wb_bridge_16_32.v
new file mode 100644 (file)
index 0000000..405e25c
--- /dev/null
+++ b/usrp2/fpga/control_lib/wb_bridge_16_32.v
@@ -0,0 +1,36 @@
+
+
+module wb_bridge_16_32
+  #(parameter AWIDTH=16)
+    (input wb_clk, input wb_rst,
+     input A_cyc_i, input A_stb_i, input A_we_i, input [3:0] A_sel_i,
+     input [AWIDTH-1:0] A_adr_i, input [31:0] A_dat_i, output [31:0] A_dat_o, output A_ack_o,
+     output B_cyc_o, output B_stb_o, output B_we_o, output [1:0] B_sel_o,
+     output [AWIDTH-1:0] B_adr_o, output [15:0] B_dat_o, input [15:0] B_dat_i, input B_ack_i
+     );
+
+   reg [15:0]           holding;
+   reg                          phase;
+   
+   assign               B_adr_o = {A_adr_i[AWIDTH-1:2],phase,1'b0};
+   assign               B_cyc_o = A_cyc_i;
+   assign               B_stb_o = A_stb_i;
+   assign               B_we_o = A_we_i;
+
+   assign               B_dat_o = ~phase ? A_dat_i[15:0] : A_dat_i[31:16];
+   assign               B_sel_o = ~phase ? A_sel_i[1:0] : A_sel_i[3:2];
+
+   assign               A_dat_o = {B_dat_i,holding};
+   assign               A_ack_o = phase & B_ack_i;
+
+   always @(posedge wb_clk)
+     if(wb_rst)
+       phase <= 0;
+     else if(B_ack_i)
+       phase <= ~phase;
+
+   always @(posedge wb_clk)
+     if(~phase & B_ack_i)
+       holding <= B_dat_i;
+   
+endmodule // wb_bridge_16_32