Fix compilation error on OS X (#730)
[proxmark3-svn] / fpga / lf_edge_detect.v
1 //-----------------------------------------------------------------------------
2 // Copyright (C) 2014 iZsh <izsh at fail0verflow.com>
3 //
4 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
5 // at your option, any later version. See the LICENSE.txt file for the text of
6 // the license.
7 //-----------------------------------------------------------------------------
8 // input clk is 24Mhz
9 `include "min_max_tracker.v"
10
11 module lf_edge_detect(input clk, input [7:0] adc_d, input [7:0] lf_ed_threshold,
12 output [7:0] max, output [7:0] min,
13 output [7:0] high_threshold, output [7:0] highz_threshold,
14 output [7:0] lowz_threshold, output [7:0] low_threshold,
15 output edge_state, output edge_toggle);
16
17 min_max_tracker tracker(clk, adc_d, lf_ed_threshold, min, max);
18
19 // auto-tune
20 assign high_threshold = (max + min) / 2 + (max - min) / 4;
21 assign highz_threshold = (max + min) / 2 + (max - min) / 8;
22 assign lowz_threshold = (max + min) / 2 - (max - min) / 8;
23 assign low_threshold = (max + min) / 2 - (max - min) / 4;
24
25 // heuristic to see if it makes sense to try to detect an edge
26 wire enabled =
27 (high_threshold > highz_threshold)
28 & (highz_threshold > lowz_threshold)
29 & (lowz_threshold > low_threshold)
30 & ((high_threshold - highz_threshold) > 8)
31 & ((highz_threshold - lowz_threshold) > 16)
32 & ((lowz_threshold - low_threshold) > 8);
33
34 // Toggle the output with hysteresis
35 // Set to high if the ADC value is above the threshold
36 // Set to low if the ADC value is below the threshold
37 reg is_high = 0;
38 reg is_low = 0;
39 reg is_zero = 0;
40 reg trigger_enabled = 1;
41 reg output_edge = 0;
42 reg output_state;
43
44 always @(posedge clk)
45 begin
46 is_high <= (adc_d >= high_threshold);
47 is_low <= (adc_d <= low_threshold);
48 is_zero <= ((adc_d > lowz_threshold) & (adc_d < highz_threshold));
49 end
50
51 // all edges detection
52 always @(posedge clk)
53 if (enabled) begin
54 // To enable detecting two consecutive peaks at the same level
55 // (low or high) we check whether or not we went back near 0 in-between.
56 // This extra check is necessary to prevent from noise artifacts
57 // around the threshold values.
58 if (trigger_enabled & (is_high | is_low)) begin
59 output_edge <= ~output_edge;
60 trigger_enabled <= 0;
61 end else
62 trigger_enabled <= trigger_enabled | is_zero;
63 end
64
65 // edge states
66 always @(posedge clk)
67 if (enabled) begin
68 if (is_high)
69 output_state <= 1'd1;
70 else if (is_low)
71 output_state <= 1'd0;
72 end
73
74 assign edge_state = output_state;
75 assign edge_toggle = output_edge;
76
77 endmodule
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