From e84f3bb467784700cb8099b93706ff00b8cdf86c Mon Sep 17 00:00:00 2001
From: iceman1001 <iceman1001@iuse.se>
Date: Wed, 1 Jan 2020 20:44:51 +0100
Subject: [PATCH] add hf plot fpga stuff (@piwi)

---
 fpga/hi_get_trace.v | 155 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 155 insertions(+)
 create mode 100755 fpga/hi_get_trace.v

diff --git a/fpga/hi_get_trace.v b/fpga/hi_get_trace.v
new file mode 100755
index 000000000..3e7412f7a
--- /dev/null
+++ b/fpga/hi_get_trace.v
@@ -0,0 +1,155 @@
+//-----------------------------------------------------------------------------
+//
+// piwi, Feb 2019
+//-----------------------------------------------------------------------------
+
+module hi_get_trace(
+       ck_1356megb,
+       adc_d, trace_enable, major_mode,
+       ssp_frame, ssp_din, ssp_clk
+);
+    input ck_1356megb;
+    input [7:0] adc_d;
+	input trace_enable;
+	input [2:0] major_mode;
+    output ssp_frame, ssp_din, ssp_clk;
+
+// clock divider
+reg [6:0] clock_cnt;
+always @(negedge ck_1356megb)
+begin
+	clock_cnt <= clock_cnt + 1;
+end
+
+// sample at 13,56MHz / 8. The highest signal frequency (subcarrier) is 848,5kHz, i.e. in this case we oversample by a factor of 2
+reg [2:0] sample_clock;
+always @(negedge ck_1356megb)
+begin
+	if (sample_clock == 3'd7)
+		sample_clock <= 3'd0;
+	else
+		sample_clock <= sample_clock + 1;
+end
+
+
+reg [11:0] addr;
+reg [11:0] start_addr;
+reg [2:0] previous_major_mode;
+reg write_enable1;
+reg write_enable2;
+always @(negedge ck_1356megb)
+begin
+	previous_major_mode <= major_mode;
+	if (major_mode == `FPGA_MAJOR_MODE_HF_GET_TRACE)
+	begin
+		write_enable1 <= 1'b0;
+		write_enable2 <= 1'b0;
+		if (previous_major_mode != `FPGA_MAJOR_MODE_HF_GET_TRACE) // just switched into GET_TRACE mode
+			addr <= start_addr;
+		if (clock_cnt == 7'd0)
+		begin
+			if (addr == 12'd3071)
+				addr <= 12'd0;
+			else
+				addr <= addr + 1;
+		end
+	end
+	else if (major_mode != `FPGA_MAJOR_MODE_OFF)
+	begin
+		if (trace_enable)
+		begin
+			if (addr[11] == 1'b0)
+			begin
+				write_enable1 <= 1'b1;
+				write_enable2 <= 1'b0;
+			end
+			else
+			begin
+				write_enable1 <= 1'b0;
+				write_enable2 <= 1'b1;
+			end
+			if (sample_clock == 3'b000)
+			begin
+				if (addr == 12'd3071)
+				begin
+					addr <= 12'd0;
+					write_enable1 <= 1'b1;
+					write_enable2 <= 1'b0;
+				end
+				else
+					addr <= addr + 1;
+			end
+		end
+		else
+		begin
+			write_enable1 <= 1'b0;
+			write_enable2 <= 1'b0;
+			start_addr <= addr;
+		end
+	end
+	else // major_mode == `FPGA_MAJOR_MODE_OFF
+	begin
+		write_enable1 <= 1'b0;
+		write_enable2 <= 1'b0;
+		if (previous_major_mode != `FPGA_MAJOR_MODE_OFF && previous_major_mode != `FPGA_MAJOR_MODE_HF_GET_TRACE) // just switched off
+			start_addr <= addr;
+	end
+end
+
+
+// (2+1)k RAM
+reg [7:0] D_out1, D_out2;
+reg [7:0] ram1 [2047:0];
+reg [7:0] ram2 [1023:0];
+
+always @(negedge ck_1356megb)
+begin
+	if (write_enable1)
+	begin
+		ram1[addr[10:0]] <= adc_d;
+		D_out1 <= adc_d;
+	end
+	else
+		D_out1 <= ram1[addr[10:0]];
+	if (write_enable2)
+	begin
+		ram2[addr[9:0]] <= adc_d;
+		D_out2 <= adc_d;
+	end
+	else
+		D_out2 <= ram2[addr[9:0]];
+end
+
+
+// SSC communication to ARM
+reg ssp_clk;
+reg ssp_frame;
+reg [7:0] shift_out;
+
+always @(negedge ck_1356megb)
+begin
+    if(clock_cnt[3:0] == 4'd0)        // update shift register every 16 clock cycles
+	begin
+		if(clock_cnt[6:4] == 3'd0)    // either load new value
+		begin
+			if (addr[11] == 1'b0)
+				shift_out <= D_out1;
+			else
+				shift_out <= D_out2;
+		end
+		else                          // or shift left
+            shift_out[7:1] <= shift_out[6:0];
+	end
+
+	ssp_clk <= ~clock_cnt[3];       // ssp_clk frequency = 13,56MHz / 16 = 847,5 kHz
+
+	if(clock_cnt[6:4] == 3'b000)    // set ssp_frame for 0...31
+		ssp_frame <= 1'b1;
+	else
+		ssp_frame <= 1'b0;
+
+end
+
+assign ssp_din = shift_out[7];
+
+endmodule