Opinions on this DIY O-Scope?

Discussion in 'General Electronics Chat' started by TheLaw, Aug 28, 2011.

  1. TheLaw

    Thread Starter Member

    Sep 2, 2010
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    First off, before you bash me with the "there's no such thing as a good DIY oscilloscope" stuff...The intent of this project would not be to create the world's best oscilloscope, rather something to tinker around with and to examine basic waveforms...not critiquing the output of a SMPS or anything.

    Disclaimer out of the way! Now the real topic. There's a possibility that you've run across this scope, and this might be old news, but for some reason, I do like the simplicity of it and the fact that I can build it from scratch. Specification wise, it's about equivalent to the popular JYE Tech oscilloscope kit. Same resolution screen and shares many other similarities.

    The positive side is that you don't have to pay $60+ for about $20 in parts.

    He's still working on it. A new firmware was released a few months ago. It's completely open by the looks of it.

    http://www.serasidis.gr/circuits/AVR_oscilloscope/avr_oscilloscope.htm

    Here's a video of it in action.
    http://www.youtube.com/watch?v=05y4wFSBUT4&feature=player_embedded#!

    Any opinions on this? Any possible improvements you guys see? Some might say it's a waste of time, but somehow I think it might be interesting to try..as it can be literally a tiny fraction of the cost of any production meter...even the tiny pocket DSOs...

    I do have a few questions about it, but I won't ask them until I'm dedicated to it.

    Thanks!
     
    Last edited: Aug 28, 2011
  2. Markd77

    Senior Member

    Sep 7, 2009
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    I wouldn't say the specifications were similar to the JYEtech, for example the old JYEtech samples at 2 Msamples per second. This one is much slower, it doesen't say exactly but he says that it can display a 5KHz square wave, which might mean it could be as low as 20Ksamples per second.

    That said, it's not going to cost much to build and see if it is any use.
     
  3. TheLaw

    Thread Starter Member

    Sep 2, 2010
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    How do you go about improving sampling rate? Is it just a matter of I/O pins? RAM? The ADC?

    I'm wondering if it can be improved at all...

    Well the general concept is similar to the JYE Tech...;)
     
  4. strantor

    AAC Fanatic!

    Oct 3, 2010
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    I found that a while back and thought "AWESOME!" and decided to make one, but then was distracted by something shiny and the rest is history. Now I have a tektronix so I've lost the need for it, but let me know if it works
     
  5. TheLaw

    Thread Starter Member

    Sep 2, 2010
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    I don't know if I'm going to make one or not. I'm still a little confused with finding a compatible LCD display. I found one with matching pinouts to the one he uses, but I'm not sure if difference in the display drivers matter etc.

    If I went on a super budget, I could probably build for like $20...If I wanted something a little more quality, and maybe a power supply so you don't have to use batteries, probably around $40, which is still better than the Jye Tech and still cheaper than a DSO Nano/Quad etc.

    Still contemplating though.
     
  6. JingleJoe

    Member

    Jul 23, 2011
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    SURRENDER TO VALVES! Banish thine digital witchcraft!
     
  7. Markd77

    Senior Member

    Sep 7, 2009
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    Well, the JYEtech uses an external parallel ADC which connects to 9 pins (8 data + clock) of the microcontroller instead of using the internal ADC.
    You could go for that approach if you modify the code somewhat (and have enough pins).
    There are schematics here:
    http://www.jyetech.com/Support/Documents.php
     
  8. tom66

    Senior Member

    May 9, 2009
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    I don't think it's much good.

    For example 7.7kHz max frequency. That's way less than even audio.

    You can pick up a cheap analog oscilloscope which will easily beat this for around $50 in most places... a store nearby me sells them for around £40 for a simple 20 MHz model.
     
  9. TheLaw

    Thread Starter Member

    Sep 2, 2010
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    I absolutely suck with programming. I've done a lot of PC programming in a simplified IDE but straight-up MCU programming is still giving me trouble.

    However, I might drop him a line. There's 8 ADC pins on the MCU which is probably enough for an external ADC...but I'm would not know how to implement it, mostly code wise.

    Though...I haven't actually looked over the code. It might not be that hard.
     
  10. tom66

    Senior Member

    May 9, 2009
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    Well, an ADC pin is just a digital pin which can read an analog voltage, not a pin for connecting to an external ADC.

    It might be possible - it depends on whether you can build it without requiring another oscilloscope!
     
  11. Markd77

    Senior Member

    Sep 7, 2009
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    I just had a look at the source code, (I don't program in C but I can partly understand it), he seems to have put a lot of code in the loop that reads the ADC and stores it in RAM, so without a lot of modification it would be hard to make it go at full speed with an external ADC and it could go faster with the internal ADC if it was written differently.
    It's possibly not the best starting point for that reason.
    He did link to this project, which looks better:
    http://www.semifluid.com/?p=15#more-15
    or there could be other open source oscilloscopes out there; it's a popular project.
     
  12. TheLaw

    Thread Starter Member

    Sep 2, 2010
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    Yeah not dedicated to this project, though it would be interesting where he takes it. Obviously not going to complain since it's open..

    I'm looking at the semifluid one right now..Anyone have any good open o-scope projects theyve seen? (One's that aren't too extravagant or expensive). I'm trying to keep it under $50, as going above would probably defeat the purpose.
     
  13. TheLaw

    Thread Starter Member

    Sep 2, 2010
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    http://www.khazama.com/project/oscope/default-en.aspx

    This is probably the most legit one I've found.

    What does that mean? It was written on the website.
     
  14. TheLaw

    Thread Starter Member

    Sep 2, 2010
    228
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    http://www.ne.jp/asahi/shared/o-family/ElecRoom/AVRMCOM/AVROscilo2/AVROscilo2.html

    Wow! It's in Japanese so you'll have to use Google translate to translate it. The wording is a little off, expectantly, so I'm having a hard time really reading it well.

    But this is a game changer right here. Lot's of control and seems simple enough.

    Only thing I'm worried about, is again, the code. And how to get it running.

    That and the LCD. This particular one uses the KS0107 based LCD, while some of the ones I've been looking at use KS0108. Are they interchangeable?
     
  15. upand_at_them

    Active Member

    May 15, 2010
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    The question is: Do you actually want an oscilloscope, or do you just want a cute toy?

    Anyone who actually needs a scope buys a real scope and doesn't play around. If you just want a toy then go for it.
     
  16. colinb

    Active Member

    Jun 15, 2011
    351
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    The KS0108 and KS0107 are used together on 128x64 LCD modules.

    The KS0108 is a 64-channel dot-matrix segment driver.
    The KS0107 is a 64-channel dot-matrix common driver.

    There are usually two KS0108 chips on a 128x64 LCD and one KS0107. This is why the KS0108/KS0107 driver code has to deal with two chip-select signals: there are actually two chips, each driving one half of the display.

    For an even more complex example, see section 3, LCD Panel Interface Application Circuit on page 15 of the KS0108B data sheet. This shows a 480x128 LCD panel using eight (8!!) KS0108B chips and two KS0107B chips.
     
  17. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
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    I've been impressed with the DSO Nano and DSO Nano 2 portable scopes

    $80 for the Nano, good for Audio range, single channel

    $200 for the Nano II, DUal Channel, good for hundreds of Khz, and 2 digital channels for seeing what is happening on a bus or somesuch.

    Great value, cheap, and useable. If you want one for your bench, I'd suggest looking at a hobbyist to repairman grade scope in the $200-$800 range.
     
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