clock_freq_p; time prev_time; @(posedge clk)(1,prev_time=$realtime) |=> ($realtime-prev_time ==100ns); endproperty a: assert property(clock_freq_p); This property checks if the clock is running at 10MHz by checking if the time between two positive edges is 100ns (period of a 10MHz clock). It uses $realtime to get the current simulation time and saves the previous time in prev_time. On every positive edge, it checks if the difference between current and previous time is 100ns.

1. ASSERTION
GOUTAMI

2. WHAT IS ASSERTION???
• Assertions are primarily used to validate the behavior of a design
• Check the occurrence of a specific condition or sequence of events.

4. TYPES OF ASSERTION
IMMEDIATE ASSERTION
1] Immediate assertions check for a
condition at the zero/current simulation
time.
2]An immediate assertion is the same as
an if..else statement with assertion
control. Immediate assertions have to be
placed in a procedural block definition.
CONCURRENT ASSERTION
• 1] Concurrent assertions check the
sequence of events spread over
multiple clock cycles
• 2]The test expression is evaluated at
clock edges based on the sampled
values of the variables involved,it can
be placed in a procedural block,
a module, an interface or a
program definition

5. Types cont..
• 3] syntax :
• label: assert(expression)
action_block;
Ex: always @(posedge clk) assert
(a && b);
• 3]syntax:
• c_assert: assert
property(@(posedge clk) not(a
&& b));

6. BUILDING
BLOCKS OF
ASSERTION

7. IMPLECATION OPERATOR
1]Need of Implication Operator ??
sequence seq;
@(posedge clk) a ##2 b;
endsequence
2]TYPES OF IMPLICATION OPERATOR
A] OVERLAPPING IMPLICATION OPERATOR
B] NON-OVERLAPPING IMPLICATION OPERATOR

8. OVERLAPPING IMPLICATION
OPERATOR

9. NON-OVERLAPPING IMPLICATION OPERATOR

10. THE IMPLICATIONWITH A FIXED DELAY
ON THE CONSEQUENT
• property p;
• @(posedge clk) a |-> ##2 b;
• endproperty
• a: assert property(p);

11. THE IMPLICATION WITH A SEQUENCE AS
AN ANTECEDENT
• property p;
• @(posedge clk) a |-> ##2 b;
• endproperty
• a: assert property(p);

12. THE IMPLICATION WITH A SEQUENCE AS
AN ANTECEDENT
• sequence seq_1;
• (a && b) ##1 c;
• endsequence
•
• sequence seq_2;
• ##2 !d;
• endsequence
•
• property p;
• @(posedge clk) seq_1 |-> seq_2;
• endpeoperty
• a: assert property(p);

13. THE IMPLICATION WITH A SEQUENCE AS
AN ANTECEDENT
• sequence seq_1;
• (a && b) ##1 c;
• endsequence
•
• sequence seq_2;
• ##2 !d;
• endsequence
•
• property p;
• @(posedge clk) seq_1 |-> seq_2;
• endpeoperty
• a: assert property(p);

14. SIMPLE DELAY ASSERTION

15. ASSERTION WITH DELAY RANGES

16. $rose

17. $fell

18. $stable
• Property stable_p checks when signal “a” asserts high, it checks for no
change in signal “b”. It means, signal “b” should stay as it was in
the previous cycle.

19. $past

20. Disable Iff

21. REPETITION OPERATOR
1] Consecutive repetition operator
2] Go to repetition operator
3] Non Consecutive repetition operator

22. Consecutive repetition operator:
Signal_name1 [->n] ##1
signal_name2

23. Go to repetition operator:

24. Non Consecutive repetition operator

25. IF ELSE
INSIDE
PROPERTY

26. $ONEHOT
PROPERTY

27. Throughout:

28. LOCAL VARIABLE
INSIDE
PROPERTY:

29. Question:::
• 1] check if clock of given frequency is working fine or not.
.lets assume duty cycle as 50% ???
Or
Write a checker to see if clock is running at 10MHZ?

30. Answer:
Property clock_freq_p;
time prev_time;
@(posedge clk)(1,prev_time=$realtime) |=> ($realtime-prev_time ==TP);
endproperty