added hitag2 reading in crypto mode functionality
[proxmark3-svn] / fpga / lo_edge_detect.v
1 //-----------------------------------------------------------------------------
2 // The way that we connect things in low-frequency simulation mode. In this
3 // case just pass everything through to the ARM, which can bit-bang this
4 // (because it is so slow).
5 //
6 // Jonathan Westhues, April 2006
7 //-----------------------------------------------------------------------------
8
9 module lo_edge_detect(
10 pck0, ck_1356meg, ck_1356megb,
11 pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4,
12 adc_d, adc_clk,
13 ssp_frame, ssp_din, ssp_dout, ssp_clk,
14 cross_hi, cross_lo,
15 dbg,
16 divisor,
17 lf_field
18 );
19 input pck0, ck_1356meg, ck_1356megb;
20 output pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4;
21 input [7:0] adc_d;
22 output adc_clk;
23 input ssp_dout;
24 output ssp_frame, ssp_din, ssp_clk;
25 input cross_hi, cross_lo;
26 output dbg;
27 input [7:0] divisor;
28 input lf_field;
29
30 // Divide the clock to be used for the ADC
31 reg [7:0] pck_divider;
32 reg clk_state;
33
34 wire tag_modulation;
35 assign tag_modulation = ssp_dout & !lf_field;
36 wire reader_modulation;
37 assign reader_modulation = !ssp_dout & lf_field & clk_state;
38
39 // No logic, straight through.
40 assign pwr_oe1 = 1'b0; // not used in LF mode
41 assign pwr_oe2 = tag_modulation;
42 assign pwr_oe3 = tag_modulation;
43 assign pwr_oe4 = tag_modulation;
44 assign ssp_clk = cross_lo;
45 assign pwr_lo = reader_modulation;
46 assign pwr_hi = 1'b0;
47 assign dbg = ssp_frame;
48
49 always @(posedge pck0)
50 begin
51 if(pck_divider == divisor[7:0])
52 begin
53 pck_divider <= 8'd0;
54 clk_state = !clk_state;
55 end
56 else
57 begin
58 pck_divider <= pck_divider + 1;
59 end
60 end
61
62 assign adc_clk = ~clk_state;
63
64 // Toggle the output with hysteresis
65 // Set to high if the ADC value is above 200
66 // Set to low if the ADC value is below 64
67 reg is_high;
68 reg is_low;
69 reg output_state;
70
71 always @(posedge pck0)
72 begin
73 if((pck_divider == 8'd7) && !clk_state) begin
74 is_high = (adc_d >= 8'd190);
75 is_low = (adc_d <= 8'd70);
76 end
77 end
78
79 always @(posedge is_high or posedge is_low)
80 begin
81 if(is_high)
82 output_state <= 1'd1;
83 else if(is_low)
84 output_state <= 1'd0;
85 end
86
87 assign ssp_frame = output_state;
88
89 endmodule
90
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