Remove remnant junk and TODO -> FIXME

[proxmark3-svn] / fpga / lo_passthru.v

diff --git a/fpga/lo_passthru.v b/fpga/lo_passthru.v
index 381426953888f0c0f409e3b707206c07496ea2fd..5c59d11ca6de2c2ac36faf0d1fc4c78ca36e21d7 100644 (file)
--- a/fpga/lo_passthru.v
+++ b/fpga/lo_passthru.v
@@ -1,35 +1,56 @@
-//-----------------------------------------------------------------------------\r
-// For reading TI tags, we need to place the FPGA in pass through mode\r
-// and pass everything through to the ARM\r
-//-----------------------------------------------------------------------------\r
-\r
-module lo_passthru(\r
-    pck0, ck_1356meg, ck_1356megb,\r
-    pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4,\r
-    adc_d, adc_clk,\r
-    ssp_frame, ssp_din, ssp_dout, ssp_clk,\r
-    cross_hi, cross_lo,\r
-    dbg\r
-);\r
-    input pck0, ck_1356meg, ck_1356megb;\r
-    output pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4;\r
-    input [7:0] adc_d;\r
-    output adc_clk;\r
-    input ssp_dout;\r
-    output ssp_frame, ssp_din, ssp_clk;\r
-    input cross_hi, cross_lo;\r
-    output dbg;\r
-\r
-// No logic, straight through.\r
-\r
-assign pwr_oe3 = 1'b0;\r
-assign pwr_oe1 = 1'b1;\r
-assign pwr_oe2 = 1'b1;\r
-assign pwr_oe4 = 1'b1;\r
-assign pwr_lo = 1'b0;\r
-assign pwr_hi = 1'b0;\r
-assign adc_clk = 1'b0;\r
-assign ssp_din = cross_lo;\r
-assign dbg = cross_lo;\r
-\r
-endmodule\r
+//-----------------------------------------------------------------------------
+// For reading TI tags, we need to place the FPGA in pass through mode
+// and pass everything through to the ARM
+//-----------------------------------------------------------------------------
+
+module lo_passthru(
+    pck0, ck_1356meg, ck_1356megb,
+    pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4,
+    adc_d, adc_clk,
+    ssp_frame, ssp_din, ssp_dout, ssp_clk,
+    cross_hi, cross_lo,
+    dbg, divisor
+);
+    input pck0, ck_1356meg, ck_1356megb;
+    output pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4;
+    input [7:0] adc_d;
+    output adc_clk;
+    input ssp_dout;
+    output ssp_frame, ssp_din, ssp_clk;
+    input cross_hi, cross_lo;
+    output dbg;
+    input [7:0] divisor;
+
+reg [7:0] pck_divider;
+reg ant_lo;
+
+// this task runs on the rising egde of pck0 clock (24Mhz) and creates ant_lo
+// which is high for (divisor+1) pck0 cycles and low for the same duration
+// ant_lo is therefore a 50% duty cycle clock signal with a frequency of
+// 12Mhz/(divisor+1) which drives the antenna as well as the ADC clock adc_clk
+always @(posedge pck0)
+begin
+       if(pck_divider == divisor[7:0])
+               begin
+                       pck_divider <= 8'd0;
+                       ant_lo = !ant_lo;
+               end
+       else
+       begin
+               pck_divider <= pck_divider + 1;
+       end
+end
+
+// the antenna is modulated when ssp_dout = 1, when 0 the
+// antenna drivers stop modulating and go into listen mode
+assign pwr_oe3 = 1'b0;
+assign pwr_oe1 = ssp_dout;
+assign pwr_oe2 = ssp_dout;
+assign pwr_oe4 = ssp_dout;
+assign pwr_lo = ant_lo && ssp_dout;
+assign pwr_hi = 1'b0;
+assign adc_clk = 1'b0;
+assign ssp_din = cross_lo;
+assign dbg = cross_lo;
+
+endmodule