//----------------------------------------------------------------------------- // Copyright (C) 2014 iZsh // // This code is licensed to you under the terms of the GNU GPL, version 2 or, // at your option, any later version. See the LICENSE.txt file for the text of // the license. //----------------------------------------------------------------------------- // // There are two modes: // - lf_ed_toggle_mode == 0: the output is set low (resp. high) when a low // (resp. high) edge/peak is detected, with hysteresis // - lf_ed_toggle_mode == 1: the output is toggling whenever an edge/peak // is detected. // That way you can detect two consecutive edges/peaks at the same level (L/H) // // Output: // - ssp_frame (wired to TIOA1 on the arm) for the edge detection/state // - ssp_clk: cross_lo `include "lp20khz_1MSa_iir_filter.v" `include "lf_edge_detect.v" module lo_edge_detect( input pck0, input pck_divclk, output pwr_lo, output pwr_hi, output pwr_oe1, output pwr_oe2, output pwr_oe3, output pwr_oe4, input [7:0] adc_d, output adc_clk, output ssp_frame, input ssp_dout, output ssp_clk, input cross_lo, output dbg, input lf_field, input lf_ed_toggle_mode, input [7:0] lf_ed_threshold ); wire tag_modulation = ssp_dout & !lf_field; wire reader_modulation = !ssp_dout & lf_field & pck_divclk; // No logic, straight through. assign pwr_oe1 = 1'b0; // not used in LF mode assign pwr_oe3 = 1'b0; // base antenna load = 33 Ohms // when modulating, add another 33 Ohms and 10k Ohms in parallel: assign pwr_oe2 = tag_modulation; assign pwr_oe4 = tag_modulation; assign ssp_clk = cross_lo; assign pwr_lo = reader_modulation; assign pwr_hi = 1'b0; // filter the ADC values wire data_rdy; wire [7:0] adc_filtered; assign adc_clk = pck0; lp20khz_1MSa_iir_filter adc_filter(pck0, adc_d, data_rdy, adc_filtered); // detect edges wire [7:0] high_threshold, highz_threshold, lowz_threshold, low_threshold; wire [7:0] max, min; wire edge_state, edge_toggle; lf_edge_detect lf_ed(pck0, adc_filtered, lf_ed_threshold, max, min, high_threshold, highz_threshold, lowz_threshold, low_threshold, edge_state, edge_toggle); assign dbg = lf_ed_toggle_mode ? edge_toggle : edge_state; assign ssp_frame = lf_ed_toggle_mode ? edge_toggle : edge_state; endmodule