![Open workbench logic sniffer](https://bajdi.com/wp-content/uploads/2013/02/open-workbench-logic-sniffer-1024x683.jpg)
Open workbench logic sniffer
I bought me an Open Bench Logic Sniffer for Christmas. And I’ve finally found some time to try it out. I’ve bought to many toys to play with the last months 🙂 I bought it from Seeedstudio for 50$, but that didn’t include the probe cable. That cost another 6$, very cheap but I had a bit of bad luck. The cable arrived damaged, on 2 wires there is some missing insulation 🙁 I’ll have to order a couple of new ones with my next order from Seeedstudio.
![Probe cable](https://bajdi.com/wp-content/uploads/2013/02/probe-cable-1-1024x683.jpg)
Probe cable
The Open Bench Logic Sniffer is an open source logic analyzer. It’s designed to support the SUMP logic analyzer software at the lowest possible cost. The project is a collaboration between the Gadget Factory and Dangerous Prototypes.
I copied the above sentence from this page. There you’ll find all the information about the Open Bench Logic Sniffer.
I bought the logic analyzer as I’m using quite a lot of devices that use the serial, I2C or SPI bus. With a logic analyzer you can see what is happening on the bus and analyze the data.
I was a bit worried that I would not get the software to work but it turned out to be very straight forward. I use Gentoo/GNU Linux on my workstation. I already had the right kernel configuration, you need kernel support for “USB Modem”. I then downloaded the Logic Sniffer Client and fired it up.
To test the Open Bench Logic Analyzer I connected it to the I2C bus of my Bajduino Mega 3A. I had 2 I2C devices connected to the Bajduino, a DS3231 RTC and an I2C LCD.
![Open bench logic sniffer](https://bajdi.com/wp-content/uploads/2013/02/open-bench-logic-sniffer-1-1024x683.jpg)
Open bench logic sniffer
When I first tried capturing data I didn’t get much result. I then figured out that the default sampling rate is 200MHz. I use the Arduino Wire library to talk to the I2C devices which is only 100kHz. So I set it the sampling rate to 5MHz and got some better results.
![Logic sniffer](https://bajdi.com/wp-content/uploads/2013/02/logic-sniffer-1-1024x562.jpg)
Logic sniffer
I then selected tools -> I2C protocol analyzer and clicked analyze. The software automatically detected which channel is SDA and SCL and analyzed the data. These are the results I got:
![I2C analysis results](https://bajdi.com/wp-content/uploads/2013/02/I2C-analysis-results-1-1024x562.jpg)
I2C analysis results
I’ve also connected the Open Bench Logic Sniffer to the SPI bus of an ATMega328 and analyzed some data. Works pretty well, I did sometimes have to try and capture the data more then once to get a good result. But that could be due to the cheap probe cable.