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Michael Karas
04/25/10 23:03
Modified:
  04/25/10 23:26

Read: 566 times
Beaverton Or
USA


 
#175374 - Look Very Carefully
Responding to: Jez Smith's previous message
Do look very carefully at what you actually get with the Logic unit. At some level of analysis it is almost a toy. From looking at the tech specs it is clear that this unit does not have very much internal memory. In fact just enough to act as an elastic buffer between the sample rate and the transfers of sample data across the USB cable. This becomes particularly clear when you look at their description of the top sample rate clocking at 24MHz. What they say is that the unit can sample at 24 MHz when it is on a USB2.0 connection and there are no others devices sharing the same host controller. If there is lag in the computer or other processing going on they say right out that the top sample rate may be slower.

I downloaded the software trial to verify something else that I suspected from looking at the web page. The unit only supports internally generated sample clocking. No external clocking is supported, at least from the simplified options selections seen in the software. In my book this is a severe limitation for some applications such as trapping read and/or write data from a parallel bus at one sample per transaction.

It is kind of astounding, with the speeds of SDRAM memory these days (i.e. DDR2 or DDR3) that you would find a unit such as this not taking advantage of those speeds to build a low cost logic analyzer that had deeeeeeeeeep memory and at the same time have that memory right in the pod to support clocking at rates at up to 80 or even 100MHz. Then transfer the data over USB after the trace has been taken.

Some years ago I did a paper design for a Logic Analyzer design that I wanted to consider making into a product. At the time I say the design as a Cypress USB MCU, a DDR memory (two chips run in ping pong to get 2X data storage rate and deep size) and a medium sized FPGA to implement all the real time control of the memory and the trigger logic. That was back in about 2005 and even then my budget estimates showed a profitable product at a sale price of some where between $89 and $119 depending upon if the unit has 1x or 2x RAM chips populated. Project stopped when I ended up moving across the country and started working with Intel.

Michael Karas



List of 25 messages in thread
TopicAuthorDate
Has anyone used one of these?      Jez Smith      04/25/10 13:15      
   No?      Jez Smith      04/25/10 13:33      
      NICE      Steve M. Taylor      04/25/10 13:49      
   yet another fancy soundcard      Jan Waclawek      04/25/10 14:30      
      Humor      Per Westermark      04/25/10 14:55      
      I think      Jez Smith      04/25/10 14:57      
         I'm definitely interested in this one      Per Westermark      04/25/10 15:27      
         But can you actually buy one?      Andy Neil      04/26/10 00:05      
            Hardware      Jez Smith      04/26/10 00:10      
            Stock Available      Michael Karas      04/26/10 00:53      
         Intronix      Andrew Ayre      04/26/10 10:54      
            Sample compression      Per Westermark      04/26/10 11:29      
               I use the Intronix...      Jan Waclawek      04/26/10 14:06      
                  Definitely a lot of work in the software      Per Westermark      04/26/10 14:41      
   Look Very Carefully      Michael Karas      04/25/10 23:03      
      DIY...      Andy Neil      04/26/10 04:47      
         wxWidgets      Per Westermark      04/26/10 05:15      
            It's not the GUI part      Andy Neil      04/26/10 06:26      
               Quite easy to use drawing primitives      Per Westermark      04/26/10 06:44      
                  product is similar to usbee      J. Guy      04/26/10 10:54      
         DIY? Kind Of      Michael Karas      04/26/10 06:14      
      it's a long way from idea to the real stuff      Jan Waclawek      04/26/10 14:21      
         Efforts Are Huge!!      Michael Karas      04/26/10 17:00      
            oh, no, thanks,..      Jan Waclawek      04/26/10 21:46      
   Look Very Carefully      Michael Karas      04/25/10 23:03      

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