Added firmware support for adc_mux to handle swapping I/Q, etc.

[debian/gnuradio] / usrp2 / fpga / sdr_lib / dsp_core_rx.v

diff --git a/usrp2/fpga/sdr_lib/dsp_core_rx.v b/usrp2/fpga/sdr_lib/dsp_core_rx.v
index a2569a1dcaa98ec9bcbb8d6acdb2d43a35e8502c..0e4af37fb3c4d31f4d6bf44949d0beb80e789312 100644 (file)
--- a/usrp2/fpga/sdr_lib/dsp_core_rx.v
+++ b/usrp2/fpga/sdr_lib/dsp_core_rx.v
@@ -56,17 +56,26 @@ module dsp_core_rx
      (.clk(clk),.rst(rst),.strobe(set_stb),.addr(set_addr),
       .in(set_data),.out(muxctrl),.changed());
 
+   // The TVRX connects to what is called adc_b, thus A and B are
+   // swapped throughout the design.
+   //
+   // In the interest of expediency and keeping the s/w sane, we just remap them here.
+   // The I & Q fields are mapped the same:
+   // 0 -> "the real A" (as determined by the TVRX)
+   // 1 -> "the real B"
+   // 2 -> const zero
+   
    always @(posedge clk)
-     case(muxctrl[1:0])
-       0: adc_i <= adc_a_ofs;
-       1: adc_i <= adc_b_ofs;
+     case(muxctrl[1:0])                // The I mapping
+       0: adc_i <= adc_b_ofs;  // "the real A"
+       1: adc_i <= adc_a_ofs;
        2: adc_i <= 0;
        default: adc_i <= 0;
      endcase // case(muxctrl[1:0])
           
    always @(posedge clk)
-     case(muxctrl[3:2])
-       0: adc_q <= adc_b_ofs;
+     case(muxctrl[3:2])                // The Q mapping
+       0: adc_q <= adc_b_ofs;  // "the real A"
        1: adc_q <= adc_a_ofs;
        2: adc_q <= 0;
        default: adc_q <= 0;