Contact an Expert

Thread: How to maximize state analyzer capture depth?


Permlink Replies: 3 - Pages: 1 - Last Post: Jun 15, 2012 12:17 AM Last Post By: mike.kirk Threads: [ Previous | Next ]
mike.kirk

Posts: 8
Registered: 11/03/11
How to maximize state analyzer capture depth?
Posted: Jan 30, 2012 10:04 AM
Click to report abuse...   Click to reply to this thread Reply
Hi,

I have two 16557D modules in my 16702b mainframe. These offer 2Msa capture depth per channel.

I am capturing a serial data stream (6 MHz gated clock, frame sync and data => 3 signals, channels 0,1,2) over time with a faster (24 MHz) state state J clock input.

Is there an app. note, manual/guide or other document that offers ideas on how sequentially trigger other channels to go beyond the 2 MSa capture limit?
e.g. can I remap the unused channels (3-15) on this pod to store more of the signals on channels 0-2? Or possibly expand using other pods?

Best case would be something like: 4 pods x 16 channels per pod x 2 MSa depth = 96 MSa of storage / 3 signals (clk/sync/data) => 32 Msa of capture depth
With 2 16557d cards, that could be doubled to 64MSa depth

Or maybe a serial to parallel converter technique that would take 8/16 serial bits and store them in parallel in the capture memory?

As far as recovering the "compressed" data, I can write a post-processing tool that will extract the captured data in the correct order of capture.

Regards,
Mike
mike.kirk

Posts: 8
Registered: 11/03/11
Re: How to maximize state analyzer capture depth?
Posted: Jan 30, 2012 10:14 AM   in response to: mike.kirk in response to: mike.kirk
Click to report abuse...   Click to reply to this thread Reply
Correction to my math:

Best case would be something like: 4 pods x 16 channels per pod x 2 MSa depth = 128 MSa of storage / 3 signals (clk/sync/data) => 42 MSa of capture depth
With 2 16557d cards, that could be doubled to 84 MSa depth
algoss


Posts: 587
Registered: 11/03/06
Re: How to maximize state analyzer capture depth?
Posted: Jan 30, 2012 11:25 AM   in response to: mike.kirk in response to: mike.kirk
Click to report abuse...   Click to reply to this thread Reply
Mike,

The capability that you are asking for does not exist, at least not within the LA HW. The data from a single physical external channel is, for the most part, connected directly to a single physical internal bit location. This means that if you only have 3 physical wires connected to your target, then approximately 95% (65/68) of the LA memory will not be used.

There are some things you can do in State mode, with some buses, using the Master/Slave or Demux modes to improve the situation by a factor of two. In Timing mode, you can go into half-channel/double-depth mode.

I had a very large customer who asked for this capability a few years ago. They only needed 1->4 fanout (16 -> 64 channels). It required an external box with some special programming, and only worked with the 16900 family of analyzers and cards. In their case, they were using the 256M cards, and this gave them 1G samples of data per capture. It was a pretty expensive solution.

As you note, besides the HW changes necessary to accommodate this, a number of SW changes would be required to reconstruct the data into a single stream. There are some tools that could do this on the 16900 Family, and, in theory, you could do this on a 16700 also using the optional SW development environment (whose name escapes me just now).

Depending on exactly what your signals look like, there might be another solution. Advanced Logical Devices http://www.ald.com has an external box for connecting to I2C, SPI and RS-232. It converts the serial bitstream to parallel, and passes it to the LA that way. On at least one of the buses, they have a decoder. If your bitstream looks like one of the buses they support, you might be able to get much better memory utilization out of your LA.

Al
mike.kirk

Posts: 8
Registered: 11/03/11
Re: How to maximize state analyzer capture depth?
Posted: Jan 30, 2012 12:35 PM   in response to: mike.kirk in response to: mike.kirk
Click to report abuse...   Click to reply to this thread Reply
Hi Al,

Thanks for your response.

Your idea of serial to parallel translation on the front end (before the LA) makes the most sense.
Let me see if ALD would meet my needs.

Regards,
Mike

Point your RSS reader here for a feed of the latest messages in all forums