Changes for page ESO to VHDL Testbench

Last modified by Richard Kreissig on 2023/09/14 11:12
<
From version < 3.1 >
edited by gjo
on 2013/07/04 11:51
To version < 6.1 >
edited by gjo
on 2013/07/04 15:07
>
Change comment: There is no comment for this version

Summary

Details

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Content
... ... @@ -2,15 +2,15 @@
2 2  
3 3  ----
4 4  
5 -The testbench is a VHDL file wich is used by ISE Simulator to test a VHDL component.
5 +The testbench is a VHDL file which is used by ISE Simulator to test a VHDL component.
6 6  
7 7  ISE is a programming an simulation tool to develop XILINX FPGAs. This work suite include a programminng workspace, a compiler, simulator (ISIM) and much more.
8 8  
9 -When you program a new component, aou also want to test its behavior. But you always have an FPGA, so you can use a simulator. So that the simulator knows what input signals to simulate you need a so called tesbench.
9 +When you program a new component, you also want to test its behavior. But you do not always have an FPGA, so you could use a simulator. For that the simulator knows what input signals to simulate you need a so called tesbench.
10 10  
11 -A testbench lists the component you want to test e.g. abo. (You have written a vhdl file which behaves like ABO and this component is also called abo). And it instantiate this componant as a Unit Under Test (UUT). This component (uut) will be tested with the input and outputs you have specified later in a test process.
11 +A testbench lists the component you want to test e.g. abo. (You have written a vhdl file which behaves like ABO and this component is also called abo). It instantiate this componant as a Unit Under Test (UUT). This component (uut) will be tested with the input and outputs you have specified in a test process.
12 12  
13 -At first a testbench code example from ABO for better understanding.
13 +At first a testbench code example from ABO is shown for better understanding.
14 14  
15 15  {{code linenumbers="true"}}
16 16  --/*****************************************************************************/
... ... @@ -66,7 +66,6 @@
66 66  constant tick_period : time := 100 ns;
67 67  
68 68  BEGIN
69 -
70 70   uut: abo PORT MAP(
71 71   tick => tick,
72 72   reset => reset,
... ... @@ -80,7 +80,6 @@
80 80   B_out => B_out
81 81   );
82 82  
83 -
84 84   tick_process: process
85 85   begin
86 86   tick <= '0';
... ... @@ -89,7 +89,6 @@
89 89   wait for tick_period/2;
90 90   end process;
91 91  
92 -
93 93   -- Stimulus process
94 94   stim_proc: process
95 95   begin
... ... @@ -97,7 +97,6 @@
97 97  
98 98   --sim Process
99 99  
100 -
101 101   --NEW TRACE
102 102   reset <= '1';
103 103   wait for tick_period;
... ... @@ -215,12 +215,12 @@
215 215  Line 55: instantiation of uut
216 216  
217 217  (% style="margin-left: 30.0px;" %)
218 -Here ABO is instantiated
214 +Here is ABO instantiated
219 219  
220 220  Line 69: tick process
221 221  
222 222  (% style="margin-left: 30.0px;" %)
223 -The tick process simulates the tick. This signal is a kind of clock signal. Its cycle duration is set in variable tick_period.
219 +The tick process simulates the tick. This signal is a kind of a clock signal. Its cycle duration is set in variable tick_period.
224 224  
225 225  Line 79: the simulation process
226 226  
... ... @@ -232,9 +232,9 @@
232 232  
233 233  ----
234 234  
235 -Therefor the core ESO contains no information about input and output signals the proper SCL model is needed to generate the testbench.
231 +Therefore the core ESO contains no information about input and output signals the proper SCL model is needed to generate the testbench.
236 236  
237 -The variable declaration must fit to the used variables in the ESO file, logically.
233 +The variable declaration must conform to the used variables in the ESO file, logically.
238 238  
239 239  |=(((
240 240  SCL Model
... ... @@ -330,41 +330,52 @@
330 330  SCL file is not realy correct, will be corrected as soon as possible
331 331  {{/note}}
332 332  
333 -The lines 23 to 66 (testbench file) are generated from SCL model file. The model tells the transformation which input and output the abo component must have and the type of these variables (signals in VHDL). So the SCl file is loaded and the needed code is generated.
329 +The lines 23 to 66 (testbench file) were generated from the SCL model file. The model tells the transformation which input and output the abo component must have and the type of these variables (signals in VHDL). So the SCl file is needed for code generation.
334 334  
335 335  
336 336  
337 -The simulation process (starts at line 79) is generated using the core ESO file. How the simulation process is generated will be schown at the follwing example:
333 +The simulation process (starts at line 79) is generated using the core ESO file. How the simulation process is generated will be shown at the following example:
338 338  
339 -|=(((
335 +|=(% colspan="1" %)(% colspan="1" %)
336 +(((
337 +SCL
338 +)))|=(((
340 340  ESO trace
341 341  )))|=(% colspan="1" %)(% colspan="1" %)
342 342  (((
343 343  Testbench
344 344  )))
345 -|(((
344 +|(% colspan="1" %)(% colspan="1" %)
345 +(((
346 +{{code linenumbers="true" language="java"}}
347 +module test
348 +input A ;
349 +input B : boolean = false;
350 +input B_value : integer = 0;
351 +input C :boolean = false;
352 +input C_value :boolean = false;
353 +output D;
354 +output E : boolean = false;
355 +output E_value : integer = 5;
356 +output F : boolean = false;
357 +output F_value : boolean = false;
358 +{
359 + //pause;
360 +}
361 +{{/code}}
362 +)))|(((
346 346  {{code linenumbers="true" language="perl"}}
347 347  !reset;
348 -A B(5) C(false)
349 -%Output: D E(3) F(false)
365 +A C(false)
366 +%Output: D F(false)
350 350  ;
351 351  {{/code}}
352 352  
353 -normally the core ESO is used, but
370 +normally the core ESO is used, but for better unterstanding we use the normal ESO trace
354 354  
355 - for better unterstanding we use the
356 -
357 - normal ESO trace
358 -
359 359  
360 360  )))|(% colspan="1" %)(% colspan="1" %)
361 361  (((
362 -
363 -
364 -
365 -
366 -
367 -
368 368  {{code linenumbers="true" language="java"}}
369 369  A <= true;
370 370  B <= false;
... ... @@ -384,20 +384,32 @@
384 384   report "1st trace: 1st tick: F_value should have been false"
385 385   severity ERROR;
386 386  {{/code}}
394 +)))
387 387  
388 -
396 +**Set inputs**
389 389  
390 -
398 +Line 2 and 3 in the testbench are setting the inputs. All (!) inputs must be set!
391 391  
392 -
393 -)))
400 +* Pure signal which are present are set to the according value, e.g. //A<=true;//
401 +* Valued signals which are present are set to their according value e.g. //C_value <= false;// and set present //B<=true;//
402 +* ABSENT values (not listed in ESO files inputs) must be set absent
403 +** pure singals (not listed) e.g. K <= false
404 +** valued signals e.g. //B <= false//, only the present value will be set, the valued signal is not touched
394 394  
395 -Line 2 and 3 in the testbench are setting the inpute. All (!) inputs must be set! Signal which are present are set to the according value
406 +**Wait for the tick to pass by**
396 396  
397 -
408 +The code //wait for tick_period;// waits for one tick, so the Hardware can compute the output values.
398 398  
399 -
410 +**Test Outputs**
400 400  
412 +After the tick has passed by we must check if the hardware computes the correct outputs. This is done by assertions. Every (!) output must be tested!
413 +
414 +* Pure signals: Test the pure output signal according to the current ESO tick, if listed in the tick, e.g. //assert( D = true )//. If it is not specified in the trace test for absence,
415 +* Valued signals: For valued signals, that are specified in the current ESO tick, test the present singal and the valued signal, e.g.// assert( F = true ) //and// assert( F_value = false)//
416 +* Valued signals, which are not listed in the current tick in the ESO file: test only the present flag for absence (We can say anything about absent valued signals)
417 +
418 +If an assertion failed the corresponding error will be printed to a log file. The severity level tells the simulator to go on with the simulation although an error occur.
419 +
401 401  
402 402  
403 403  
Confluence.Code.ConfluencePageClass[0]
Id
... ... @@ -1,1 +1,1 @@
1 -7111244
1 +7111276
URL
... ... @@ -1,1 +1,1 @@
1 -https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/KIELER/pages/7111244/ESO to VHDL Testbench
1 +https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/KIELER/pages/7111276/ESO to VHDL Testbench

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