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1 | //----------------------------------------------------------------------------- |
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2 | // Copyright (C) 2014 iZsh <izsh at fail0verflow.com> |
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3 | // |
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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. |
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7 | //----------------------------------------------------------------------------- |
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8 | // |
9 | // There are two modes: |
10 | // - lf_ed_toggle_mode == 0: the output is set low (resp. high) when a low |
11 | // (resp. high) edge/peak is detected, with hysteresis |
12 | // - lf_ed_toggle_mode == 1: the output is toggling whenever an edge/peak |
13 | // is detected. |
14 | // That way you can detect two consecutive edges/peaks at the same level (L/H) |
15 | // |
16 | // Output: |
17 | // - ssp_frame (wired to TIOA1 on the arm) for the edge detection/state |
18 | // - ssp_clk: cross_lo |
19 | `include "lp20khz_1MSa_iir_filter.v" |
20 | `include "lf_edge_detect.v" |
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21 | |
22 | module lo_edge_detect( |
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23 | input pck0, input pck_divclk, |
24 | output pwr_lo, output pwr_hi, |
25 | output pwr_oe1, output pwr_oe2, output pwr_oe3, output pwr_oe4, |
26 | input [7:0] adc_d, output adc_clk, |
27 | output ssp_frame, input ssp_dout, output ssp_clk, |
28 | input cross_lo, |
29 | output dbg, |
30 | input lf_field, |
31 | input lf_ed_toggle_mode, input [7:0] lf_ed_threshold |
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32 | ); |
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33 | |
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34 | wire tag_modulation = ssp_dout & !lf_field; |
35 | wire reader_modulation = !ssp_dout & lf_field & pck_divclk; |
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36 | |
37 | // No logic, straight through. |
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38 | assign pwr_oe1 = 1'b0; // not used in LF mode |
39 | assign pwr_oe3 = 1'b0; // base antenna load = 33 Ohms |
40 | // when modulating, add another 33 Ohms and 10k Ohms in parallel: |
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41 | assign pwr_oe2 = tag_modulation; |
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42 | assign pwr_oe4 = tag_modulation; |
43 | |
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44 | assign ssp_clk = cross_lo; |
45 | assign pwr_lo = reader_modulation; |
46 | assign pwr_hi = 1'b0; |
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47 | |
48 | // filter the ADC values |
49 | wire data_rdy; |
50 | wire [7:0] adc_filtered; |
51 | assign adc_clk = pck0; |
52 | lp20khz_1MSa_iir_filter adc_filter(pck0, adc_d, data_rdy, adc_filtered); |
53 | |
54 | // detect edges |
55 | wire [7:0] high_threshold, highz_threshold, lowz_threshold, low_threshold; |
56 | wire [7:0] max, min; |
57 | wire edge_state, edge_toggle; |
58 | lf_edge_detect lf_ed(pck0, adc_filtered, lf_ed_threshold, |
59 | max, min, |
60 | high_threshold, highz_threshold, lowz_threshold, low_threshold, |
61 | edge_state, edge_toggle); |
62 | |
63 | assign dbg = lf_ed_toggle_mode ? edge_toggle : edge_state; |
64 | |
65 | assign ssp_frame = lf_ed_toggle_mode ? edge_toggle : edge_state; |
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66 | |
67 | endmodule |
68 | |