X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/1eb874ee3f7690cc92a720c0636fbe100e82b1e5..437035a75b2737d0b36886bc2bacaeb0219c6325:/fpga/hi_simulate.v?ds=sidebyside

diff --git a/fpga/hi_simulate.v b/fpga/hi_simulate.v
index 0768c29d..8d70bb1b 100644
--- a/fpga/hi_simulate.v
+++ b/fpga/hi_simulate.v
@@ -16,6 +16,13 @@
 // Jonathan Westhues, October 2006
 //-----------------------------------------------------------------------------
 
+// possible mod_types:
+`define NO_MODULATION        3'b000
+`define MODULATE_BPSK        3'b001
+`define MODULATE_212K        3'b010
+`define MODULATE_424K        3'b100
+`define MODULATE_424K_8BIT   3'b101
+
 module hi_simulate(
     pck0, ck_1356meg, ck_1356megb,
     pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4,
@@ -35,10 +42,6 @@ module hi_simulate(
     output dbg;
     input [2:0] mod_type;
 
-// Power amp goes between LOW and tri-state, so pwr_hi (and pwr_lo) can
-// always be low.
-assign pwr_hi = 1'b0;
-assign pwr_lo = 1'b0;
 
 // The comparator with hysteresis on the output from the peak detector.
 reg after_hysteresis;
@@ -51,38 +54,29 @@ begin
 end
 
 
-// Divide 13.56 MHz by 32 to produce the SSP_CLK
-// The register is bigger to allow higher division factors of up to /128
-reg [10:0] ssp_clk_divider;
+// Divide 13.56 MHz to produce various frequencies for SSP_CLK
+// and modulation.
+reg [7:0] ssp_clk_divider;
 
 always @(posedge adc_clk)
     ssp_clk_divider <= (ssp_clk_divider + 1);
 
 reg ssp_clk;
-reg ssp_frame;
+
 always @(negedge adc_clk)
 begin
-    //If we're in 101, we only need a new bit every 8th carrier bit (53Hz). Otherwise, get next bit at 424Khz
-    if(mod_type == 3'b101)
-    begin
-	if(ssp_clk_divider[7:0] == 8'b00000000)
-	    ssp_clk <= 1'b0;
-	if(ssp_clk_divider[7:0] == 8'b10000000)
-	    ssp_clk <= 1'b1;
-
-    end
+    if(mod_type == `MODULATE_424K_8BIT)
+      // Get bit every at 53KHz (every 8th carrier bit of 424kHz)
+      ssp_clk <= ssp_clk_divider[7];
+    else if(mod_type == `MODULATE_212K)
+      // Get next bit at 212kHz
+      ssp_clk <= ssp_clk_divider[5];
     else
-    begin
-	if(ssp_clk_divider[4:0] == 5'd0)//[4:0] == 5'b00000)
-	    ssp_clk <= 1'b1;
-	if(ssp_clk_divider[4:0] == 5'd16) //[4:0] == 5'b10000)
-	    ssp_clk <= 1'b0;
-    end
+      // Get next bit at 424Khz
+      ssp_clk <= ssp_clk_divider[4];
 end
 
 
-//assign ssp_clk = ssp_clk_divider[4];
-
 // Divide SSP_CLK by 8 to produce the byte framing signal; the phase of
 // this is arbitrary, because it's just a bitstream.
 // One nasty issue, though: I can't make it work with both rx and tx at
@@ -96,46 +90,45 @@ always @(negedge ssp_clk)
     ssp_frame_divider_from_arm <= (ssp_frame_divider_from_arm + 1);
 
 
-
+reg ssp_frame;
 always @(ssp_frame_divider_to_arm or ssp_frame_divider_from_arm or mod_type)
-    if(mod_type == 3'b000) // not modulating, so listening, to ARM
+    if(mod_type == `NO_MODULATION) // not modulating, so listening, to ARM
         ssp_frame = (ssp_frame_divider_to_arm == 3'b000);
     else
-	ssp_frame = (ssp_frame_divider_from_arm == 3'b000);
+        ssp_frame = (ssp_frame_divider_from_arm == 3'b000);
 
 // Synchronize up the after-hysteresis signal, to produce DIN.
 reg ssp_din;
 always @(posedge ssp_clk)
     ssp_din = after_hysteresis;
 
-// Modulating carrier frequency is fc/16, reuse ssp_clk divider for that
+// Modulating carrier frequency is fc/64 (212kHz) to fc/16 (848kHz). Reuse ssp_clk divider for that.
 reg modulating_carrier;
 always @(mod_type or ssp_clk or ssp_dout)
-    if(mod_type == 3'b000)
+    if (mod_type == `NO_MODULATION)
         modulating_carrier <= 1'b0;                          // no modulation
-    else if(mod_type == 3'b001)
+    else if (mod_type == `MODULATE_BPSK)
         modulating_carrier <= ssp_dout ^ ssp_clk_divider[3]; // XOR means BPSK
-    else if(mod_type == 3'b010)
-	modulating_carrier <= ssp_dout & ssp_clk_divider[5]; // switch 212kHz subcarrier on/off
-    else if(mod_type == 3'b100 || mod_type == 3'b101)
-	modulating_carrier <= ssp_dout & ssp_clk_divider[4]; // switch 424kHz modulation on/off
+    else if (mod_type == `MODULATE_212K)
+        modulating_carrier <= ssp_dout & ssp_clk_divider[5]; // switch 212kHz subcarrier on/off
+    else if (mod_type == `MODULATE_424K || mod_type == `MODULATE_424K_8BIT)
+        modulating_carrier <= ssp_dout & ssp_clk_divider[4]; // switch 424kHz modulation on/off
     else
         modulating_carrier <= 1'b0;                           // yet unused
 
-// This one is all LF, so doesn't matter
-assign pwr_oe2 = modulating_carrier;
 
-// Toggle only one of these, since we are already producing much deeper
+// Load modulation. Toggle only one of these, since we are already producing much deeper
 // modulation than a real tag would.
-assign pwr_oe1 = modulating_carrier;
-assign pwr_oe4 = modulating_carrier;
+assign pwr_hi = 1'b0;                   // HF antenna connected to GND
+assign pwr_oe3 = 1'b0;                  // 10k Load
+assign pwr_oe1 = modulating_carrier;    // 33 Ohms Load
+assign pwr_oe4 = modulating_carrier;    // 33 Ohms Load
+
+// This is all LF and doesn't matter
+assign pwr_lo = 1'b0;
+assign pwr_oe2 = 1'b0;
 
-// This one is always on, so that we can watch the carrier.
-assign pwr_oe3 = 1'b0;
 
-assign dbg = modulating_carrier;
-//reg dbg;
-//always @(ssp_dout)
-//    dbg <= ssp_dout;
+assign dbg = ssp_din;
 
 endmodule