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  • Author Author: fmanno
  • Date Created: Date Created
  • Views 916 views
  • Likes 1 like
  • Comments 4 comments
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Raspberry ScoPi

fmanno

Hi all,

I received my Raspberry Pi a few weeks ago and I've been preparing for a project. One of the main issues when developing hardware is the dificulty to "see" the signals we're working with and debug our projects or prototypes. Osciloscopes are often either very expensive or very low-end. With the versatility of the Raspberry Pi to connect to almost ANY display (specially now with the Pi View) and its computing power I had the idea of building an additional board to turn the pi into a digital osciloscope. With the versatility given by the Linux OS plus the accesibility of I/O pins for H/W interface the Pi could be a very powerful protocol analyzer. The model B is perfect for this application because of the extra memory and the ethernet port wich would allow for remote measurements even without the need for a display!! If it even comes to that.

 

imageThe board basics will be:

  • Voltage translators to enable the pi to connect to higher voltage buses
  • At least 2 A/D channels (maybe 4 but I'm not sure)
  • Analog signal preconditioning
  • Memory for temporal storage of data
  • Isolated inputs from the I/O pins in the Raspberry Pi to protect from high voltages or currents
  • It will be powered independently from the Pi (because of the isolation needed) with all required voltages generated in the board from single 5V supply
  • OpenHardware and Opensource project so the community could work on it make suggestions and improvements

 

Future developments could include a version of Linux with a Real Time Kernel in order to make more accurate timing measurements

 

The Raspberry Pi is a perfect tool to encourage Software development, the basic idea behind the project is to help turn it into a perfect tool for Hardware hacking too. Imagine when you could design a new expansion board for the Pi with the Pi, manufacture it, then test it also with the Pi and finally use it! It would make for a very powerful, very complete developing tool. I'm still in the planning stages but hope to start soon. I look forward to be sharing my progress and hearing your comments soon!

 

Good luck to all! image

 

imageEDIT: I need help, anybody know someplace like google.code to host the files of the project? Because google.code only accepts OSI approved licenses and I'm liking this Creative Commons one which seems not to be OSI approved http://creativecommons.org/licenses/by-nc-sa/3.0/ Thanks!

  • fmanno wrote:

     

    I need help, anybody know someplace like google.code to host the files of the project? Because google.code only accepts OSI approved licenses and I'm liking this Creative Commons one which seems not to be OSI approved http://creativecommons.org/licenses/by-nc-sa/3.0/ Thanks!

    Why don't you post the hardware files and documents here at element14 as part of your personal content?  Google Code might still be a good place for the software part, especially if you want source code control.  It also has a decent Issues tracker.  Besides, as long as the software is covered under one of the OSI licenses I don't think Google cares if other content like documentation is Creative Commons.

  • in reply to morgaine

    Thanks for the comments! I'm glad to see some interest!

    @Morgaine: I'm aware of those two tools you mention. That's why I'm going to start with and pay more attention to the aquisition of analog signals which . Also because I'm more of an analog guy. I don't know all of the features of those tools (gotta do some research) but for what I'm seeing I'm aiming to something in the middle of both. The Open Bench Logic Sniffer has a lot of logic inputs and the Bus Pirate has very few, aimed at serial communications moslty. I'll go for something in between, like 8-16 digital channels to complement the analog channels. However both projects will be very helpful to get ideas. Thanks for pointing to them!

     

    P.S. I'm not making any promises but possibly next week I'l start posting some schematics.

  • Hi fmanno, I'm an avid supporter of open hardware instrumentation and open source EDA tools, and was very happy to see your project intentions on the blog.  It'll be a lot of work for you to do a good job, but hopefully worth the effort.

     

    Logic analysers are extremely useful tools, and I'm sure you're aware of the best known open hardware LA, the Open_Bench_Logic_Sniffer , which costs $50 fully assembled (I have one of these).  I mention it because it provides good background against which to develop a new LA.  For example it wouldn't make much sense to develop a product that costs more but does less than the OBLS (except as a learning exercise of course, which is always worthwhile).

     

    In addition, because the OBLS is open hardware, you could potentially take advantage of its openness and use its front-end sampling circuitry as a starting point for your own LA.  Also, the OBLS's software is of course open source, available at http://www.lxtreme.nl/ols/ , and it could potentially be of use to you directly or give you some ideas for your own project.

     

    Finally, the Bus_Pirate is always worth a mention, a highly multi-functional open hardware instrument that can also do a certain amount of logic and protocol analysis and even doubles as a (very slow) oscilloscope, all for $30 asembled.  I have one of these as well, and it's really handy to have around.

     

    I'm looking forward to see what you come up with! image

     

    Morgaine.

  • Hi fmanno

     

    looking forward to se how you get on with your project, will be following image