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1 | //----------------------------------------------------------------------------- | |
2 | // | |
3 | // piwi, Feb 2019 | |
4 | //----------------------------------------------------------------------------- | |
5 | ||
6 | module hi_get_trace( | |
7 | ck_1356megb, | |
8 | adc_d, trace_enable, major_mode, | |
9 | ssp_frame, ssp_din, ssp_clk | |
10 | ); | |
11 | input ck_1356megb; | |
12 | input [7:0] adc_d; | |
13 | input trace_enable; | |
14 | input [2:0] major_mode; | |
15 | output ssp_frame, ssp_din, ssp_clk; | |
16 | ||
17 | // clock divider | |
18 | reg [6:0] clock_cnt; | |
19 | always @(negedge ck_1356megb) | |
20 | begin | |
21 | clock_cnt <= clock_cnt + 1; | |
22 | end | |
23 | ||
24 | // 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 | |
25 | reg [2:0] sample_clock; | |
26 | always @(negedge ck_1356megb) | |
27 | begin | |
28 | if (sample_clock == 3'd7) | |
29 | sample_clock <= 3'd0; | |
30 | else | |
31 | sample_clock <= sample_clock + 1; | |
32 | end | |
33 | ||
34 | ||
35 | reg [11:0] addr; | |
36 | reg [11:0] start_addr; | |
37 | reg [2:0] previous_major_mode; | |
38 | reg write_enable1; | |
39 | reg write_enable2; | |
40 | always @(negedge ck_1356megb) | |
41 | begin | |
42 | previous_major_mode <= major_mode; | |
43 | if (major_mode == `FPGA_MAJOR_MODE_HF_GET_TRACE) | |
44 | begin | |
45 | write_enable1 <= 1'b0; | |
46 | write_enable2 <= 1'b0; | |
47 | if (previous_major_mode != `FPGA_MAJOR_MODE_HF_GET_TRACE) // just switched into GET_TRACE mode | |
48 | addr <= start_addr; | |
49 | if (clock_cnt == 7'd0) | |
50 | begin | |
51 | if (addr == 12'd3071) | |
52 | addr <= 12'd0; | |
53 | else | |
54 | addr <= addr + 1; | |
55 | end | |
56 | end | |
57 | else if (major_mode != `FPGA_MAJOR_MODE_OFF) | |
58 | begin | |
59 | if (trace_enable) | |
60 | begin | |
61 | if (addr[11] == 1'b0) | |
62 | begin | |
63 | write_enable1 <= 1'b1; | |
64 | write_enable2 <= 1'b0; | |
65 | end | |
66 | else | |
67 | begin | |
68 | write_enable1 <= 1'b0; | |
69 | write_enable2 <= 1'b1; | |
70 | end | |
71 | if (sample_clock == 3'b000) | |
72 | begin | |
73 | if (addr == 12'd3071) | |
74 | begin | |
75 | addr <= 12'd0; | |
76 | write_enable1 <= 1'b1; | |
77 | write_enable2 <= 1'b0; | |
78 | end | |
79 | else | |
80 | addr <= addr + 1; | |
81 | end | |
82 | end | |
83 | else | |
84 | begin | |
85 | write_enable1 <= 1'b0; | |
86 | write_enable2 <= 1'b0; | |
87 | start_addr <= addr; | |
88 | end | |
89 | end | |
90 | else // major_mode == `FPGA_MAJOR_MODE_OFF | |
91 | begin | |
92 | write_enable1 <= 1'b0; | |
93 | write_enable2 <= 1'b0; | |
94 | if (previous_major_mode != `FPGA_MAJOR_MODE_OFF && previous_major_mode != `FPGA_MAJOR_MODE_HF_GET_TRACE) // just switched off | |
95 | start_addr <= addr; | |
96 | end | |
97 | end | |
98 | ||
99 | ||
100 | // (2+1)k RAM | |
101 | reg [7:0] D_out1, D_out2; | |
102 | reg [7:0] ram1 [2047:0]; | |
103 | reg [7:0] ram2 [1023:0]; | |
104 | ||
105 | always @(negedge ck_1356megb) | |
106 | begin | |
107 | if (write_enable1) | |
108 | begin | |
109 | ram1[addr[10:0]] <= adc_d; | |
110 | D_out1 <= adc_d; | |
111 | end | |
112 | else | |
113 | D_out1 <= ram1[addr[10:0]]; | |
114 | if (write_enable2) | |
115 | begin | |
116 | ram2[addr[9:0]] <= adc_d; | |
117 | D_out2 <= adc_d; | |
118 | end | |
119 | else | |
120 | D_out2 <= ram2[addr[9:0]]; | |
121 | end | |
122 | ||
123 | ||
124 | // SSC communication to ARM | |
125 | reg ssp_clk; | |
126 | reg ssp_frame; | |
127 | reg [7:0] shift_out; | |
128 | ||
129 | always @(negedge ck_1356megb) | |
130 | begin | |
131 | if(clock_cnt[3:0] == 4'd0) // update shift register every 16 clock cycles | |
132 | begin | |
133 | if(clock_cnt[6:4] == 3'd0) // either load new value | |
134 | begin | |
135 | if (addr[11] == 1'b0) | |
136 | shift_out <= D_out1; | |
137 | else | |
138 | shift_out <= D_out2; | |
139 | end | |
140 | else // or shift left | |
141 | shift_out[7:1] <= shift_out[6:0]; | |
142 | end | |
143 | ||
144 | ssp_clk <= ~clock_cnt[3]; // ssp_clk frequency = 13,56MHz / 16 = 847,5 kHz | |
145 | ||
146 | if(clock_cnt[6:4] == 3'b000) // set ssp_frame for 0...31 | |
147 | ssp_frame <= 1'b1; | |
148 | else | |
149 | ssp_frame <= 1'b0; | |
150 | ||
151 | end | |
152 | ||
153 | assign ssp_din = shift_out[7]; | |
154 | ||
155 | endmodule |