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ahb evc: Hw can I do a random back to back transfer with random address

Anukrishnan

Hi ,

I want to do a random back to back transfers, by constraining the ahb evc in specman.Basically I need the htrans as 2-0-2-2-2-2-0-2-0-2-2-2-2-  etc  with random address .So how can I constrain the ahb-evc  to get a sequence like this? Thanks in advance.

 

Parents 
  • Hello,

If I understand well, you are trying to send multiple SINGLE bursts with
some IDLE states along the way (you have to use multiple bursts, if you
want to have random addresses - due to the nature of the AHB bursts:
INCR or WRAP). A direct approach, as I see it would be like this:

extend vr_ahb_master_seq_kind : [ PATTERN_SEQ ];

extend PATTERN_SEQ vr_ahb_master_seq {
	!ahb_burst : SINGLE vr_ahb_master_driven_burst;

	body()@driver.clock is {
		//htrans will be 2
		do ahb_burst;
		
		//htrans will be 0, then 2
		do ahb_burst keeping {
			it.transmit_delay == 1;
		};

		//the other remaining bursts with htrans 2
		for i from 1 to 2 do {
			do ahb_burst;
		};
	};
};

Of course, everything will go as smooth as I said if there is no
arbitration in the environment (ex: using a single master environment
with vr_ahb_lite_env). Also the whole sequence may stretch in time, due
to hresp signal from the slave or other response then OKEY.

After this in your MAIN vr_ahb_master_seq or in your virtual sequence
you will repeatedly call the PATTERN_SEQ, defined above.

    Hope this will solve your problem.
Reply 
  • Hello,

If I understand well, you are trying to send multiple SINGLE bursts with
some IDLE states along the way (you have to use multiple bursts, if you
want to have random addresses - due to the nature of the AHB bursts:
INCR or WRAP). A direct approach, as I see it would be like this:

extend vr_ahb_master_seq_kind : [ PATTERN_SEQ ];

extend PATTERN_SEQ vr_ahb_master_seq {
	!ahb_burst : SINGLE vr_ahb_master_driven_burst;

	body()@driver.clock is {
		//htrans will be 2
		do ahb_burst;
		
		//htrans will be 0, then 2
		do ahb_burst keeping {
			it.transmit_delay == 1;
		};

		//the other remaining bursts with htrans 2
		for i from 1 to 2 do {
			do ahb_burst;
		};
	};
};

Of course, everything will go as smooth as I said if there is no
arbitration in the environment (ex: using a single master environment
with vr_ahb_lite_env). Also the whole sequence may stretch in time, due
to hresp signal from the slave or other response then OKEY.

After this in your MAIN vr_ahb_master_seq or in your virtual sequence
you will repeatedly call the PATTERN_SEQ, defined above.

    Hope this will solve your problem.
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