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My Salae Logic Analyzer Arrived

Pete Brown - 01 February 2011

When working with digital protocols, such as SPI, a logic analyzer can be indispensible. Unfortunately, they can also be really expensive. For example, my $399 oscilloscope had a LA option, but that bumped the scope price up to $1500, outside my price range and definitely outside the Wife Acceptance Factor range.

Finally, after much UPS drama (yes, this is the delivery I was complaining about on Twitter), my Salae USB logic analyzer arrived today. This is a pretty inexpensive analyzer, limited to around12 to 24mhz sample rate. I got this on the advice of Chris Walker from Netduino, when someone had mentioned needing a logic analyzer.

I hooked it up to my Netduino running my sawtooth DAC program, and looked at the output. The ability to view the actual binary (or hex, or decimal or whatever) representation of the SPI message would have saved me some real aggravation.

Here's what the app looks like sampling data from my Netduino. The tooltip is showing me the 16 bit binary message. Nice!

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The SPI settings are configured via a dialog. You can assign different functions to the pins, set the bit depth and otherwise configure how the data should be interpreted as SPI data. For SPI, messages from 1 to 64 bits are supported.

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You can see that it supports a number of protocols in the analyzer. While I'm using SPI right now, I can definitely see using I2C and Serial in the future.

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You can also see timing information when you hover over a signal. In this example, the Measurements section is telling me about section displayed with the arrows (you can't see the cursor, but that's what I hovered over)

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If you're going to be doing chip-to-chip communication, this is even more useful than an oscilloscope. Oscilloscopes are cool, and given my interest in sound wave production, are extremely useful, but this little inexpensive tool gets you down to the bits in digital communication. Note also that oscilloscopes are real-time where this analyzer records the signal for a few moments and displays the results on screen.

There are separate 32 and 64 bit Windows applications available, as well as Mac and Linux versions. I installed the app and driver (no reboot required), plugged it in without reading the manual, and let it run. It was super easy to figure out. You can't beat that. Read more about it here.

Recommended.

       
posted by Pete Brown on Tuesday, February 1, 2011
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2 comments for “My Salae Logic Analyzer Arrived”

  1. Gravatar of Johan RydmarkReply
    Johan Rydmarksays:
    Wednesday, February 2, 2011 at 2:22:44 AM
    I was in the same position looking for a scope with LA but was put of by the pricetag. Got me this little unit from Salae and I never regret that purchase! Doing a lot of 1-wire communication it turned out to be a life saver and a very valuable tool for debuging in general.
  2. Gravatar of Graham BloiceReply
    Graham Bloicesays:
    Wednesday, February 2, 2011 at 8:37:17 AM
    Pete,

    As you've already spent your money this may not interest you too much, but there is another cheap LA option that has a performance way above its cost, the Open Logic Sniffer: http://dangerousprototypes.com/docs/Open_Bench_Logic_Sniffer.

    $45 shipped worldwide (test leads are extra) that will do 16 channels at up to 100MHz.

    The unit is under heavy development, both the FPGA on the device that actually does the data capture and the various clients to visualize the data.

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