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Thread: Generate Data and clock from Agilent 16720A


Permlink Replies: 3 - Pages: 1 - Last Post: Jun 21, 2012 12:36 PM Last Post By: algoss Threads: [ Previous | Next ]
aliasnikhil

Posts: 4
Registered: 06/20/12
Generate Data and clock from Agilent 16720A
Posted: Jun 20, 2012 10:48 PM
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Hello,

I am Nikhil. I wish to generate some digital data to test my comparator ASIC. I want to generate a sequence/ pattern using the pattern generator module 16720A and test the output using Agilent 16902 Logic Analyzer.

I have the following problems:

1) The data should be at around 10KHz but the pattern generator allows a minimum rate of only 1MHz. Is it possible to generate data at lower rates?

2) I want to generate a clock along with the data, preferably with 90 degrees phase shift. This clock will be used to feed the clock input of the probe of logic analyzer. Can I do this as well?

3) I was able to generate only the data, but at high rate of 1MHz but there is no option for a clock output. To test this output, I want to use the Logic Analyzer probe. But I do not see any output, probably because of absence of clock and selecting wrong threshold levels. I am not sure if I can set the pattern generator output levels and thereby I cannot set the appropriate threshold level for Logic Analyzer. I confirmed the data output from pattern generator using an oscilloscope. It is correct except for the data rate part.
All I need now is a clock input for my probe, thereby I need to generate it along with the data using the pattern generator. And I need to generate the data at lower rates.

Can anyone please advise on how to get around these issues?

Let me know if I missed out any information that maybe needed.

Regards,
Nikhil
algoss


Posts: 608
Registered: 11/03/06
Re: Generate Data and clock from Agilent 16720A
Posted: Jun 21, 2012 6:55 AM   in response to: aliasnikhil in response to: aliasnikhil
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1) The data should be at around 10KHz but the pattern generator allows a minimum rate of only 1MHz. Is it possible to generate data at lower rates?

If you have an external clock, running at the requested speed, then you can attach that to 'Clock In', use 'External Clock' and the PG will run at the input clock rate. If you don't have an external clock source, then you will have to synthesize a slower data rate by using strings of 0's and 1's. For instance, 5 0's followed by 5 1's looks like a clock running at 1/10th of the set data rate. With the PG set to 1MHz, that would be 100KHz. To get 10 KHz, you would need 50 0's and 50 1's. A data bit would be either 100 0's or 100 1's.

2) I want to generate a clock along with the data, preferably with 90 degrees phase shift. This clock will be used to feed the clock input of the probe of logic analyzer. Can I do this as well?

To do this, for one bit, you would build a pattern with 50 rows of Data = (either 1 or 0), and Clock = 0, followed by 50 rows of Data = (same as before), and Clock = 1.

In this case, "Data" and "Clock" are arbitrary names that you have assigned to two of the channels.

This is a perfect job for the Macro capability that's built into the GUI. You either build 2 Macros, one that generates a 1, and 1 that generates a 0, or one Macro with a passed parameter, either 1 or 0.

3) I was able to generate only the data, but at high rate of 1MHz but there is no option for a clock output. To test this output, I want to use the Logic Analyzer probe. But I do not see any output, probably because of absence of clock and selecting wrong threshold levels. I am not sure if I can set the pattern generator output levels and thereby I cannot set the appropriate threshold level for Logic Analyzer. I confirmed the data output from pattern generator using an oscilloscope. It is correct except for the data rate part.

What voltages did you see on the scope?

Do you have PG pods connected to the ends of the cables? If not, then you need to get some. There are different ones for different logic families. Look in the LA help file for the various types. The cables are not intended for use without the PG pods. The voltages on the cables are a weird differential ECL that can't be used directly. Once you have pods connected, then just set the LA to the same logic family.

All I need now is a clock input for my probe, thereby I need to generate it along with the data using the pattern generator. And I need to generate the data at lower rates.

I think I answered this above.

Al
aliasnikhil

Posts: 4
Registered: 06/20/12
Re: Generate Data and clock from Agilent 16720A
Posted: Jun 21, 2012 11:24 AM   in response to: algoss in response to: algoss
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Thank you very much for this reply.

I saw voltages as -1.73V and -0.8V as the 2 voltage levels. I have a pod for the probe but I do not have a probe for the PG. So, the pod for PG converts the data into a specific format without me having to program it in the GUI, right?

Regards,
Nikhil
algoss


Posts: 608
Registered: 11/03/06
Re: Generate Data and clock from Agilent 16720A
Posted: Jun 21, 2012 12:36 PM   in response to: aliasnikhil in response to: aliasnikhil
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I saw voltages as -1.73V and -0.8V as the 2 voltage levels. I have a pod for the probe but I do not have a probe for the PG. So, the pod for PG converts the data into a specific format without me having to program it in the GUI, right?

Please read the help, starting with the Pattern Generator Overview. You will need at least one pod for the data, and one pod for the clock.

Al

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