Some documentation

[proxmark3-svn] / fpga / lo_simulate.v

diff --git a/fpga/lo_simulate.v b/fpga/lo_simulate.v
index 7eb910ba1db014b2ba2f01c317eb686dcec2e11a..57e602a2b15feb1f79e7a9374b11a2d30ac33462 100644 (file)
--- a/fpga/lo_simulate.v
+++ b/fpga/lo_simulate.v
@@ -1,37 +1,83 @@
-//-----------------------------------------------------------------------------\r
-// The way that we connect things in low-frequency simulation mode. In this\r
-// case just pass everything through to the ARM, which can bit-bang this\r
-// (because it is so slow).\r
-//\r
-// Jonathan Westhues, April 2006\r
-//-----------------------------------------------------------------------------\r
-\r
-module lo_simulate(\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
-assign pwr_oe3 = 1'b0;\r
-assign pwr_oe1 = ssp_dout;\r
-assign pwr_oe2 = ssp_dout;\r
-assign pwr_oe4 = ssp_dout;\r
-assign ssp_clk = cross_lo;\r
-assign pwr_lo = 1'b0;\r
-assign adc_clk = 1'b0;\r
-assign pwr_hi = 1'b0;\r
-assign dbg = cross_lo;\r
-\r
-endmodule\r
+//-----------------------------------------------------------------------------
+// The way that we connect things in low-frequency simulation mode. In this
+// case just pass everything through to the ARM, which can bit-bang this
+// (because it is so slow).
+//
+// Jonathan Westhues, April 2006
+//-----------------------------------------------------------------------------
+
+module lo_simulate(
+    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;
+
+// No logic, straight through.
+assign pwr_oe3 = 1'b0;
+assign pwr_oe1 = ssp_dout;
+assign pwr_oe2 = ssp_dout;
+assign pwr_oe4 = ssp_dout;
+assign ssp_clk = cross_lo;
+assign pwr_lo = 1'b0;
+assign pwr_hi = 1'b0;
+assign dbg = ssp_frame;
+
+// Divide the clock to be used for the ADC
+reg [7:0] pck_divider;
+reg clk_state;
+
+always @(posedge pck0)
+begin
+       if(pck_divider == divisor[7:0])
+               begin
+                       pck_divider <= 8'd0;
+                       clk_state = !clk_state;
+               end
+       else
+       begin
+               pck_divider <= pck_divider + 1;
+       end
+end
+
+assign adc_clk = ~clk_state;
+
+// Toggle the output with hysteresis
+//  Set to high if the ADC value is above 200
+//  Set to low if the ADC value is below 64
+reg is_high;
+reg is_low;
+reg output_state;
+
+always @(posedge pck0)
+begin
+       if((pck_divider == 8'd7) && !clk_state) begin
+               is_high = (adc_d >= 8'd200);
+               is_low = (adc_d <= 8'd64);
+       end
+end
+
+always @(posedge is_high or posedge is_low)
+begin
+       if(is_high)
+               output_state <= 1'd1;
+       else if(is_low)
+               output_state <= 1'd0;
+end
+
+assign ssp_frame = output_state;
+
+endmodule
+