Initial commit for the firmware. Used the 20090306_ela version as baseline.

It is identical to the popular 20081211, with the doob addition (20090301), a
linux client, and two additional commands for LF analysis. Let me know if
you find issues here!

fpga/hi_read_tx.v

@@ -0,0 +1,76 @@
+//-----------------------------------------------------------------------------
+// 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);
+
+assign ssp_din = 1'b0;
+
+assign pwr_lo = 1'b0;
+assign dbg = ssp_frame;
+
+endmodule