Hi all,
I'm stuck on a simple issue but can't get out of it: I would like to
generate severals waveform signals for my future testbench but the
frequency of my signals are not correct.
Below is the code I want to simulate:
1 | library ieee;
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2 | use ieee.std_logic_1164 .all;
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3 | use ieee.std_logic_arith.all;
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4 | use ieee.std_logic_unsigned.all;
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5 | use ieee.math_real.all;
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6 |
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7 | entity triangle_generator is
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8 |
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9 | generic(AMP: real;
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10 | OFFSET: real;
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11 | FREQ: real;
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12 | PHASE :real);
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13 |
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14 | port(wave1: out real);
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15 |
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16 | end triangle_generator;
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17 |
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18 | architecture archi of triangle_generator is
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19 |
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20 | signal tmp1 : real := 0.0;
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21 |
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22 |
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23 | begin
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24 |
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25 | P1:process
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26 |
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27 | constant delta : real := 1000.0e-12;
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28 | constant fin : time := 1000 ps;
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29 |
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30 | variable angle : real := 0.0;
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31 | variable t : real := 0.0;
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32 | variable PHASE_RAD : real := 0.0;
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33 |
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34 | begin
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35 |
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36 | PHASE_RAD := (math_2_pi * PHASE)/360.0;
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37 |
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38 | loop
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39 | angle := math_2_pi * FREQ * t;
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40 | t := t + delta;
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41 |
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42 | tmp1 <= OFFSET+(AMP/2.0)*(2.0/math_pi)*arcsin(sin(angle));
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43 |
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44 | wait for fin;
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45 |
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46 | end loop;
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47 |
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48 | wait;
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49 |
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50 | end process P1;
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51 |
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52 | wave1 <= tmp1;
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53 |
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54 | end archi;
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When I simule this code with FREQ=100 000 000 Hz I get the waveform in
attachment, not really what I wanted. So I was thinking, if I write
delta = 1000.0e-15 maybe it will be right, but absolutly not. When I
change the value of delta, the frequency of the waveform is wrong.
So can you help me to get through this please?
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