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d19929cb | 1 | //----------------------------------------------------------------------------- |
3b2fee43 | 2 | // Copyright (C) 2014 iZsh <izsh at fail0verflow.com> |
d19929cb | 3 | // |
3b2fee43 | 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. | |
d19929cb | 7 | //----------------------------------------------------------------------------- |
3b2fee43 | 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" | |
d19929cb | 21 | |
22 | module lo_edge_detect( | |
3b2fee43 | 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 | |
d19929cb | 32 | ); |
d19929cb | 33 | |
7cc204bf | 34 | wire tag_modulation = ssp_dout & !lf_field; |
35 | wire reader_modulation = !ssp_dout & lf_field & pck_divclk; | |
d19929cb | 36 | |
37 | // No logic, straight through. | |
38 | assign pwr_oe1 = 1'b0; // not used in LF mode | |
39 | assign pwr_oe2 = tag_modulation; | |
40 | assign pwr_oe3 = tag_modulation; | |
41 | assign pwr_oe4 = tag_modulation; | |
42 | assign ssp_clk = cross_lo; | |
43 | assign pwr_lo = reader_modulation; | |
44 | assign pwr_hi = 1'b0; | |
3b2fee43 | 45 | |
46 | // filter the ADC values | |
47 | wire data_rdy; | |
48 | wire [7:0] adc_filtered; | |
49 | assign adc_clk = pck0; | |
50 | lp20khz_1MSa_iir_filter adc_filter(pck0, adc_d, data_rdy, adc_filtered); | |
51 | ||
52 | // detect edges | |
53 | wire [7:0] high_threshold, highz_threshold, lowz_threshold, low_threshold; | |
54 | wire [7:0] max, min; | |
55 | wire edge_state, edge_toggle; | |
56 | lf_edge_detect lf_ed(pck0, adc_filtered, lf_ed_threshold, | |
57 | max, min, | |
58 | high_threshold, highz_threshold, lowz_threshold, low_threshold, | |
59 | edge_state, edge_toggle); | |
60 | ||
61 | assign dbg = lf_ed_toggle_mode ? edge_toggle : edge_state; | |
62 | ||
63 | assign ssp_frame = lf_ed_toggle_mode ? edge_toggle : edge_state; | |
d19929cb | 64 | |
65 | endmodule | |
66 |