-//-----------------------------------------------------------------------------\r
-// The way that we connect things when transmitting a command to an ISO\r
-// 15693 tag, using 100% modulation only for now.\r
-//\r
-// Jonathan Westhues, April 2006\r
-//-----------------------------------------------------------------------------\r
-\r
-module hi_read_tx(\r
- pck0, ck_1356meg, ck_1356megb,\r
- pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4,\r
- adc_d, adc_clk,\r
- ssp_frame, ssp_din, ssp_dout, ssp_clk,\r
- cross_hi, cross_lo,\r
- dbg,\r
- shallow_modulation\r
-);\r
- input pck0, ck_1356meg, ck_1356megb;\r
- output pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4;\r
- input [7:0] adc_d;\r
- output adc_clk;\r
- input ssp_dout;\r
- output ssp_frame, ssp_din, ssp_clk;\r
- input cross_hi, cross_lo;\r
- output dbg;\r
- input shallow_modulation;\r
-\r
-// The high-frequency stuff. For now, for testing, just bring out the carrier,\r
-// and allow the ARM to modulate it over the SSP.\r
-reg pwr_hi;\r
-reg pwr_oe1;\r
-reg pwr_oe2;\r
-reg pwr_oe3;\r
-reg pwr_oe4;\r
-always @(ck_1356megb or ssp_dout or shallow_modulation)\r
-begin\r
- if(shallow_modulation)\r
- begin\r
- pwr_hi <= ck_1356megb;\r
- pwr_oe1 <= ~ssp_dout;\r
- pwr_oe2 <= ~ssp_dout;\r
- pwr_oe3 <= ~ssp_dout;\r
- pwr_oe4 <= 1'b0;\r
- end\r
- else\r
- begin\r
- pwr_hi <= ck_1356megb & ssp_dout;\r
- pwr_oe1 <= 1'b0;\r
- pwr_oe2 <= 1'b0;\r
- pwr_oe3 <= 1'b0;\r
- pwr_oe4 <= 1'b0;\r
- end\r
-end\r
-\r
-// Then just divide the 13.56 MHz clock down to produce appropriate clocks\r
-// for the synchronous serial port.\r
-\r
-reg [6:0] hi_div_by_128;\r
-\r
-always @(posedge ck_1356meg)\r
- hi_div_by_128 <= hi_div_by_128 + 1;\r
-\r
-assign ssp_clk = hi_div_by_128[6];\r
-\r
-reg [2:0] hi_byte_div;\r
-\r
-always @(negedge ssp_clk)\r
- hi_byte_div <= hi_byte_div + 1;\r
-\r
-assign ssp_frame = (hi_byte_div == 3'b000);\r
-\r
-assign ssp_din = 1'b0;\r
-\r
-assign pwr_lo = 1'b0;\r
-assign dbg = ssp_frame;\r
-\r
-endmodule\r
+//-----------------------------------------------------------------------------
+// The way that we connect things when transmitting a command to an ISO
+// 15693 tag, using 100% modulation only for now.
+//
+// Jonathan Westhues, April 2006
+//-----------------------------------------------------------------------------
+
+module hi_read_tx(
+ pck0, ck_1356meg, ck_1356megb,
+ pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4,
+ adc_d, adc_clk,
+ ssp_frame, ssp_din, ssp_dout, ssp_clk,
+ cross_hi, cross_lo,
+ dbg,
+ shallow_modulation
+);
+ input pck0, ck_1356meg, ck_1356megb;
+ output pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4;
+ input [7:0] adc_d;
+ output adc_clk;
+ input ssp_dout;
+ output ssp_frame, ssp_din, ssp_clk;
+ input cross_hi, cross_lo;
+ output dbg;
+ input shallow_modulation;
+
+// The high-frequency stuff. For now, for testing, just bring out the carrier,
+// and allow the ARM to modulate it over the SSP.
+reg pwr_hi;
+reg pwr_oe1;
+reg pwr_oe2;
+reg pwr_oe3;
+reg pwr_oe4;
+always @(ck_1356megb or ssp_dout or shallow_modulation)
+begin
+ if(shallow_modulation)
+ begin
+ pwr_hi <= ck_1356megb;
+ pwr_oe1 <= ~ssp_dout;
+ pwr_oe2 <= ~ssp_dout;
+ pwr_oe3 <= ~ssp_dout;
+ pwr_oe4 <= 1'b0;
+ end
+ else
+ begin
+ pwr_hi <= ck_1356megb & ssp_dout;
+ pwr_oe1 <= 1'b0;
+ pwr_oe2 <= 1'b0;
+ pwr_oe3 <= 1'b0;
+ pwr_oe4 <= 1'b0;
+ end
+end
+
+// Then just divide the 13.56 MHz clock down to produce appropriate clocks
+// for the synchronous serial port.
+
+reg [6:0] hi_div_by_128;
+
+always @(posedge ck_1356meg)
+ hi_div_by_128 <= hi_div_by_128 + 1;
+
+assign ssp_clk = hi_div_by_128[6];
+
+reg [2:0] hi_byte_div;
+
+always @(negedge ssp_clk)
+ hi_byte_div <= hi_byte_div + 1;
+
+assign ssp_frame = (hi_byte_div == 3'b000);
+
+// Implement a hysteresis to give out the received signal on
+// ssp_din. Sample at fc.
+assign adc_clk = ck_1356meg;
+
+// ADC data appears on the rising edge, so sample it on the falling edge
+reg after_hysteresis;
+always @(negedge adc_clk)
+begin
+ if(& adc_d[7:0]) after_hysteresis <= 1'b1;
+ else if(~(| adc_d[7:0])) after_hysteresis <= 1'b0;
+end
+
+
+assign ssp_din = after_hysteresis;
+
+assign pwr_lo = 1'b0;
+assign dbg = ssp_din;
+
+endmodule