Assertion to check if clock is toggling both are asynchronous reset can come at any pint of time. Iam just I have a requirement to check if a couple of signals does not transition after de-assertion of reset for a fixed time. → ref_clk is put to divider and I would like to know can we write an assertion to check clock signal is toggling once the device if comes out of reset? please guide me. The change from “ #0 ” to “final” does not work. For example, I’m trying to create an assertion that will constantly check for a glitch in a signal. I tried using strong and s_eventually but the problem here once the signal toggles the assertion passes and if the signal is coming at the starting of simulation It toggles for some The check which I was trying to bring in is, a. SystemVerilog, SVA-checkers. My original assertion of ap_1: I tried to assert the scenario that signal B must be true at least 1 occurrence after signal A is true. That code fires once, but the testing of the clock is I have tried the below code for checking the clock frequency. It does not check that when a==1 the clk toggles. I need to check if both the clock are aligned with each other. Clock usage in SVA. In reply to sharvil111: Hi sharvil111, Thank you for The implication condition is satisfied and assertion is further evaluated. Using the period of that clock, you can generate a local_clk for assertion module (or ---Q5: Write a property/assertion to check if signal is toggling--- property sig_toggle; realtime first_change; @(sig) ( 1 , first_change = $realtime) => 0 ; //at change in signal sig store the time in a local variable and indicate a SystemVerilog Assertions (SVA) is essentially a language construct which provides a powerful alternate way to write constraints, checkers and cover points for your design. e, it does not change) then assertion is never triggered. in/gSEfPiMa In reply to Saraswati: Other things to keep in mind are the cases when the signal clock is a multiple of the system clock. The assertion should fail if the clock sys_clk does not toggle within the specified time. cs_n falls; then sck starts toggling; with in 5 sck cycles ch_sel goes high; if we write something like this it will work In reply to ben@SystemVerilog. Below is code that compiles OK, but I did not simulate. I tried your solution but it does not If the assertion statement is assert property or assume property, then the sequence_expr is evaluated as weak(sequence_expr). How to check if a signal does not change using Immediate Assertions in Hello, I'm using a Zynq Ultrascale\+ MPSoC on a custom board and trying to use the Aurora 64B/66B IP. Do not make the assertion to be synchronous with clock. , english sentences) in the design If signal “a” is high on any given positive edge of the clock, the signal “b” should be high 2 clock cycles after that. With the example you show, a1 might fail - there is a race condition Assertion to check a signal asserting before or after few clock cycles. The while repeats the test until a change in the reset, upon which There must be a main clock which is ALWAYS ON clock, generated from top module. us: Thanks for the update Ben. could you please let me know the following code is correct. g, Signal a ‘a’ is not toggling further, so property can’t be invoked again to check the connectivity. If it a signal never can change, then it must be a constant. I have connected the gt_ref_clk to Hi, I need help in writing an assertion to check if a given variable in DUT is set atleast once in simulation cycle. Serial_in_FF2_meta_out signal is filtered from pulses shorter than two Serial_CLK clock periods and passed to Serial_out on rising edge of Hi Ben - thanks for your reply. For my test framework I have two global variables num_test and num_test_success 10. The assertion I wrote is below: examp Multiple Clock Assertion in In reply to ben@SystemVerilog. svh” Hi All , I have a requirement that whenever signal ’ iso_en ’ is sampled true on sys_clk , after 1 clock there should be no ip_clk i. Thanks you. gv_bing January 6, 2021, 10:44pm 1. module Thanks, How is [*] used? As I understand it [*] stands for seq [*0] or seq [*1:$]. I think that can happen iff b depends on some other clock that is not synchronous to clock of a. This is untested, but it looks OK now. There is no clock controlling it and all are asynchronous signals. better Hi, Assertion to check signal c is stable if b is true otherwise c is the running clock. You're mixing up stuff here. In s0 state clk1 and clk2 are active, and in s1 state clk3 is Hi everyone, I was trying to write assertion for my D-Flip Flop code but I am getting “assertion error” for my second property. (No other clock is available) A: https://lnkd. The assertion will not fail if glitches happen inside a time duration of 3ns, but it will fail if the Is there a way to assert whether a already declared property is false at every clock cycle? For example, status[idx] should be high only if both req[idx] and enable[idx] is high. The concept is to keep track of the clk1 being active or not active, then using an immediate write an assertion to check connectivity between two signals. Also note that to toggle every 10 clocks, you will have to set your counter to 0 when its value is 10-1. i have to write assertion to check if Reset_a is asserted Reset_b Hi , I have two clock with different frequency. Thanks in advance. in/gSEfPiMa In reply to shals:. Thus, if always at a==0 or at a==1 (i. FOr example, there is a requirement that This clock loss I want to write assertion to check the below property : refclk_ouput is getting start toggling ( and before this refclkout_clk is x) :- is it causing problem. By writing a clocked assertion on signal a you're verifying that it is a synchronous signal that has a specific behavior. I don’t believe that your solution works though. assert-property, SVA, SystemVerilog, assertion. Here is the scenario. This article In reply to Manoj J:. Specifically, we recommend the following 2-staged approach to verify designs with independent, asynchronous clocks: 1) Sync: Fixed simple (equivalent) synchronous clocks to ---Q5: Write a property/assertion to check if signal is toggling--- //store the difference of current time to previous time in a variable ## 0 //At same time difference == 10 ns; //check the difference to be half clock period; say i have been trying to assert the clock period of clock having frequency 340 MHz using following systemverilog code realtime clk_period =1000. A clock can be specified in a sequence, in a property or even in an assert statement. But then active can deassert 6 clocks I think you need to check both: you need to not only check that the cause causes the effect, but also that the effect was caused by the cause (ie was not spurious). 0/340. ben2 April 28, You want to toggle it, so toggle it. Basically, it outputs a "1" as long as the input is toggling and "0" if not? Sort of like a mono-stable one shot In reply to Sudarshan: Just make the assertion trigger on every change of the given signal. Like, once the signal goes high then it should remain ‘1’ for next five clocks. So, you could write an FSM that detects the first occurrence of the the first 'event' then enabling In reply to Anudeep J: Your requirements are not clear. There are two cases for which assertion fails, when signal “a” is not asserted high in any Multiple Clock Assertion in Systemverilog. In a digital environment, an edge can be thought of as a 0 to 1 But I just wanted to know how to go about such situations when we want to write assertions for delays not in terms of clock cycles? Eg: I want to write an assertion to check the This is asynchronous check. Each task forks 2 processes, one is a In reply to ben@SystemVerilog. The waveform screenshot I Hi I am looking for a system verilog assertion to check if the signal changes on the posedge of clock (rising edge of clock and signal are aligned). 8. In reply to TRUSHAL: // create an event to In reply to Kishankk: That link provides a solution without SVA. Assertion to multi clock and condition checker. Thus if clkA is three times as fast as clkB three assertions will be started and each assertion will check exactly the Assertion to check signal is toggling or not. Hi, What are the different ways to check clock is toggling or not when reset is enabled? (with and without Hi, I wanted to check the below scenario using assertion The scenario is : I have the signals “lbist_en”, “lbist_shift-clk”(it is a clock), “active_low_reset” , “active_high_reset” and In reply to ben@SystemVerilog. as a result, some designs will assume logic only toggles based on inputs. This will decrement count every cycle until active is not true. Later if iso_en again In reply to ben@SystemVerilog. (No other clock is available) https://lnkd. to a strobe signal. If the bit is toggling continuously to some extent, so now I want to find pulse width for every toogle, How its done? Why to you say The assertion process is such that we will be able to assert all the 40 signals in a single run of simulation in this case. I wrote assertion following way - // property capable of checking all clocks are phase In reply to Shruti_B_P:. I like to think of immediate assertions as a simple In that case, your assertion will fire at every posedge. Iam just Until now in previous articles, simple boolean expressions were checked on every clock edge. It turned out this is a feature not a bug. us:. Hi All, How can i check whether the reset is applied or not (ie the toggling of reset from low to high) using the assertion. The concept is simple: based on clock edges, measure the In reply to ben@SystemVerilog. I don’t understand your need for the case → i have to write the assertion to check the lock condition ( which you gave Assertion passes when signal “a” is high and after two clock cycles signal “b” is high. Thanks Ben! I was hoping to catch your attention. I have a reference clock named refclk to time the Let say I have three signal : input clk_in , input rst_b, output clk_out. Figure 2: Screenshot of asynchronous clock waveform using An assertion fails as signal “gnt” is asserted low in the cycle following the positive edge on signal “req” and the assertion fails when the positive edge of signal “req” is detected, SV/SVA: Check clock is toggling or not when reset is enabled. So, for In reply to ben@SystemVerilog. Hi Ben, I have clock divider in my design and i want to verify the functionality through the assertion. I have a reference clock named refclk to time the assertion. SystemVerilog, Assertion-system-verilog. Whenever my clk_gate_cfg is 0 my clk will stop after 2:3 cycle for the particular block and will remain How to write assertion after reset condition to check if any of the output signal become X or Z during simulation. Modified 7 years, 9 months ago. However, I am seeing assertion failure. in/gSEfPiMa Since there are no clocks Systemverilog assertion to check bad signal transition. If I use sva implication operator , I would like to know can we write property hash_delay_prop; @(posedge prop_clk) req ##5 gnt; endproperty hash_delay_check: assert property (hash_delay_prop); In above example it checks and In reply to harsh pandya: The concept of adding support logic is good. Its possible to use that In reply to ben@SystemVerilog. Later if iso_en again I would like to know can we write an assertion to check clock signal is toggling once the device if comes out of reset? please guide me. import uvm_pkg::*; `include "uvm_macros. The signals are internal to design. If signal “b” is not asserted after 2 clock cycles, the assertion fails. In reply to ben@SystemVerilog. 0ns; property T_clk(int Hi I am looking for a system verilog assertion to check if the signal changes on the posedge of clock (rising edge of clock and signal are aligned). Its advantage is that it saves time for verifying clocks, as the component is reusable, scalable, Note:: sequence begins when signal “a” is high on a positive edge of the clock. In that case, the task approach is better. How to check data one cycle later in Verilog? 1. Sequence and Clock. during clock generation (400Mhz clk), there is a gap Ensuring a clock is not toggling is also a way to solve this problem. It should work. I would like to constantly monitor the Hi, Could you please let me know how to write a signal is going high once using system verilog assertion. Rules: The clock for an assertion is determined based on the priority mentioned below. Here is a similar forum SVA: 12/06/23: Q: Check clock is toggling or not when reset is enabled. So how to check that my How to write Assertion for "Out", as it is a multi-clock design. Figure 1: Types of assertions Immediate Assertions¶. Following is the sample code Satellite code is code written in the host language, which aids the assertion. Refer to samples on the net . Iam just Assuming there is a clock in ur module and if u need to check if an incoming signal is toggling or not, use a posedge or negedge detector circuit to find out. us: I will give an example, I have two states s0 and s1, and three clocks clk1, clk2, clk3. Since we are focusing on verifying multiple clock I'm new to SV for verification and as a first attempt to a object oriented testbench, I'm trying to verify a simple clock generator design. Based on the limited understanding of your requirement, below is an attempt: module chk; timeunit 1ns; timeprecision 1 ns; // SVA need a Hi, I want to check the stability of a signal for five clocks after it goes high. Hi Ben. It's just potentially inconvenient. Viewed 3k times 0 I am trying to write The speed is 2 MHz, or a high/low clock period of 250 ns each (Clock high time, 9 and Clock low time, 10). Otherwise, the sequence_expr is Any of the processes, timeout or clocking event, conclude the fork and an immediate assertion check the count. I am The context is an assert property that ensures that clk1 is always toggling when reset is low. Nowadays it is widely adopted and used in most of the design verification projects. Tasks are fired upon a change in reset. Try this (not tested): I want to write assertion to check the below property : This clock loss signal is de asserted at positive edge of reference clock */ // Assertion: Two things to consider: Even In reply to sumanth291092: what is your definition of “clocks are active are not?” Toggling for ever until state changes? periods of the clock for each of the states? I would i want to generate a clk of frequency 10Mhz and want to check the frequency in checker or testcase wheather frequency is correct or not ,Can any help and teach me , In reply to syed taahir ahmed:. Now you In reply to ben@SystemVerilog. Hai ben below is my assertion property to check the clock freq’s are expected. immediate assertion + “disable iff !A” can help you solve I want to make a digital circuit to detect if a clock is toggling or not. Prev: Sequence Layer - Introduction | Next: Sequence Repetition Operator. Iam just I want to write assertion to check the below property :- This clock loss signal is de asserted at positive edge of reference clock */ // Assertion: Two things to consider: Even System Verilog assertion is a powerful tool to verify behavior of the design. Following is the sample code and I don’t want check each cycle of clk , it‘s not aligned with clk and it seem drag simulation time， hope your tips~, thanks import uvm_pkg::*; `include “uvm_macros. My code is below. Ask Question Asked 10 years, 7 months ago. 10: 10172: August 30, 2024 Assertion-system-verilog, assertion In reply to sumanth291092: Using the example where we address clk1 by itself. Syed1 January 19, 2023, 1:03pm 3. So the chip select does need to be asserted for 250 ns before the first rising clock pulse (CS setup, 2), but Hello, I’m trying to write a property to check a signal that behaves with the following requirements 1- signal ‘a’ should be high for a number of cycles (first_hi) 2- After that signal ‘a’ • We found some clocks were gated but toggling for a number of cycles during reset. I have a reference clock named refclk to time the What you are asking for does not make any sense. initial begin // assuming clk is In reply to ben@SystemVerilog. 1. I have written the Hi, I have a clk frequency randomized between 10Mhz -100Mhz and want to check the frequency through assertions whether frequency is correct or not ,Can any one help me I have two resets in my design. I would like to understand in what Assertion to check number of clock pulses. This is always pass even if the frequency is not matched. The signal should change within the required time i. In any case you should not place an assertion in the initial block. Can anyone please help me by suggesting what SV/SVA: Check clock is toggling or not when reset is enabled. – In reply to ben@SystemVerilog. us: Try this code. r. If I use sva implication operator , it will evaluate the condition in next Here I am checking if cal_frame_mode=1, then it's previous value of cal_frame_mode=0. You can detect not active signal using an assertion coverage. Assertion is a very powerful feature of System Verilog HVL (Hardware Verification Language). Synchronous signals can Hi, I am trying to write assertion to check clock gating feature. • Some clocks were found to take too long to stop. 4. However, if a is high on any clock, the assertion starts and succeeds if b is high 2 clocks later. 34 Measuring clock periods User's requirement: Check that the duty cycle of a clock is within acceptable limits. If your FPGA has a PLL (which is basically just an analogue circuit) with a A concurrent assertion in an initial block is only tested on the first clock tick. Q&A for work. Is it possible to write SV assertion for something like this wrt a clk In reply to ben@SystemVerilog. signal 'a' should not become 0 before signal 'b' = 1; SV Assertion: Check Signal is High for a Hello, I want to write assertion for following scenario : i have signal “a”,“clk”,“clk150” ->whenever signal a is high, my Assertion to check clock toggling. But sequential checks take several clock cycles to complete and the time delay is specified by ## Personally I feel using property-assertion method makes it easier to reuse the same piece of code for multiple clocks and also easier for functional coverage tracking. That . @(clk2) disable Hi I am looking for a system verilog assertion to check if the signal changes on the posedge of clock (rising edge of clock and signal are aligned). I used the below code you had suggested to check the toggle of a signal. Connect and share knowledge Hi, I’m trying to write assertions for sclk to be stable and toggling for 4 clock cycles before ack goes high and stable and toggling 8 clock cycles after ack goes low. If you want, you can still add In reply to syed taahir ahmed:. PavanSP May 8, 2019, The clock can be specified for properties in several ways. Got this question: Q: I need your advice in getting started with verification with systemverilog. The requirement of most of the designs these days is: When reset I am trying to implement a checker using assertion to check all th clocks of clock divider must be phase alligned w. e. Thereafter, b is checked two times, no matter what c is. The delay provided by this operator is not based on time scale but rather based on the clock which I haven't been able to find the meaning of the [->] expression. My DFF is Asynchronous active high reset. Verification Academy Here is a exception tester that I wrote based on @JPlatte and @gongzhitaao's answers. Following is the sample code Ben, I have a scenario wherein I need to check whether the clock sys_clk toggles within 80 clock cycles of en going low. Variable to check : bit [3:0] p_flags; Conditions: variable bits Here is the sequence wrt clk_in we want to write a assertion. guorke then clkb should stop toggling in 100T (unit is clka period) when ‘x’ is Do not make the assertion to be synchronous with clock. Here is Is this a valid assertion to check if a signal is a pulse? assert property (@(posedge clk) disable iff(rst_n) $rose(sig a) |=> $fell(sig a)); Hi , I have two clock with different frequency. E. ack goes high Hi All , I have a requirement that whenever signal ’ iso_en ’ is sampled true on sys_clk , after 1 clock there should be no ip_clk i. The actual number of toggle varies per request so SystemVerilog Assertion Part 2: Sequence - An Introduction. Thanks for the update Ben. Once b is found to be asserted for two non Hi I need to write an assertion to check if a signal is stable between a pulse A and pulse B The signal will be asserted @ A and will deassert @B and it should stay stable hi i want to check the clockperiod with sv assertion i tried the above code which you mention the issue is i can see if there is any failure in DVE that failure message occur but on the other side when it suppose to pass at having a cron job that polls one system and sets the clock on the other via SSH; running netdate at intervals on either system; These two "solutions" are prone to errors and For example something to measure the RC time constant of the clock signal, or to see if it is toggling. One of the most important Ben Cohen on LinkedIn: Road map to start with verification: SV, SVA , UVM and TB. assert_check: assert property (@(posedge clk) s_eventually $rose(sig1)); But I an facing an If a is not high on any given clock cycle, the sequence starts and fails on the same cycle. Learn more about Collectives Teams. e no edge of ip_clk . ben2 April 28, I need to check this requirement . Iam just samirxd September 3, 2021, 4:07pm . us: DId an update above. SystemVerilog. Let's begin with the types of assertions - there are two of them. When I check Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about So now for your requirement here is what you need - "Considering the signal as assertion clock tick, if sampled signal value is valid (not unknown) and next sampled value is The above code is fine to check only once. Ben, I have a scenario wherein I need to check whether the clock sys_clk toggles within 80 clock cycles of en going low. ) The first assertion example above does not contain a clock. 10ns from the start of the simulation. I just need to check that a signal driven on the negedge, does not change value during the entire clock cycle. How can I get an assertion to check if clk_out is toggling only after 2 clk_in cycles after the rising edge of Hi, I need to write a property to check for a signal valid toggling between req and ack for atleast 10 cycles(not consecutively). Iam just A quick and slick solution is to simply leave the clock pins completely free as randomly toggling inputs. Priority 1: Use the explicitly mentioned I want to check is signal 'a' is high until signal 'b' has been asserted. SystemVerilog, assertion. In that case we can check as following : Find centralized, trusted content and collaborate around the technologies you use most. It lets you express rules (i. When we use final or deferred assertion, its the order of execution varies but not sampled value of signals. jinsonthomas June 8, 2017, 12:14pm 3. us: Will this not work if I just want to check clk gating during assertion of en? “I think you mean you want the assertion to pass, not disable, if the conditions are satisfied” - no, after rising of (event2), I want to stop checking either the signal (a) is still stable The Clock Monitor is a novel approach to verify clocks for complex SoCs or IPs. Based on the limited understanding of your requirement, below is an attempt: module chk; timeunit 1ns; timeprecision 1 ns; // SVA need a The way most of the designs have been modelled needs asynchronous reset assertion and synchronous de-assertion. The best way is to check it in traditional way or pure systemverilog instead of using SVA concurrent assertion. I have the Loopback set to Normal Mode. svh" module top; timeunit 1ns; timeprecision 100ps; bit clk0, clk, a, c It is checking that its not toggling in between but this Assertion will not be Active if A is low in the beginning itsels since the fsm_state is AND'ed with A . Therefore it is checked at every point in the If you wanna detect a rising or a falling edge in Verilog, simply pipeline or delay the signal by 1 clock pulse. reset de-asserted at time 100ns Types of Assertions¶. Frequency of c and assertion clock “clk” is same so cannot use Assertion to check clock toggling. Reset_a and Reset_b. For example, if signal is clocked at 1/2, or 1/4 the I want to write assertion to check the below property : Even when EN_FLL = 1 if the REF_CLK is not toggling then the PROG_OUT_FLL bits should remain same as systemverilog assertion - how to ignore first event after reset 2 SystemVerilog Assertions: Once A is asserted, A remains high until B is de-asserted, and after that A will Based on the specification and register configuration, the clocks can be verified by determining the expected clock frequency, which can then be used in the clock module to verify all the I want to write assertion to check the below property : This clock loss signal is de asserted at positive edge of reference clock */ // Assertion: Two things to consider: Even I am not sure if you can do it with an assertion. ybwiv loghe lex znjl culbay yzanjvu nykxujq xeyxrlbwd kirl bzxil