Author Topic: Wirelessly viewing an oscilloscope waveform?? HELP!!!  (Read 9218 times)

0 Members and 1 Guest are viewing this topic.

Offline Gearbreaker

  • Contributor
  • Posts: 17
Re: Wirelessly viewing an oscilloscope waveform?? HELP!!!
« Reply #25 on: October 02, 2010, 04:00:31 am »
Thank you for the input.....  I'm checking into it.....  32 channels and 1/3 the price may make it worth making my own case.    Chris.


im not sure if it meets your requirements, but the Open Bench is 1/3 the price of the saleae and is open source.
http://dangerousprototypes.com/2010/02/25/prototype-open-logic-sniffer-logic-analyzer-2/

http://www.gadgetfactory.net/index.php?main_page=index&cPath=10
 

Offline Zero999

  • Super Contributor
  • ***
  • Posts: 14194
  • Country: gb
  • 0999
Re: Wirelessly viewing an oscilloscope waveform?? HELP!!!
« Reply #26 on: October 02, 2010, 06:44:45 am »
The minimum frequency to be monitored is around 10Hz and the maximum is around 30Khz.
Will the PWM be working at 30kHz?

If so what's the shortest pulse width of minimum/maximum duty cycle?

The data needs to be sampled at double the highest frequency signal of interest but a 30kHz PWM signal will have much higher frequency components than 30kHz. The minimum/maximum duty cycle will increase the highest frequency component and if you want to see glitches between different waveforms, the frequency might even be higher.

 

alm

  • Guest
Re: Wirelessly viewing an oscilloscope waveform?? HELP!!!
« Reply #27 on: October 02, 2010, 07:12:14 am »
im not sure if it meets your requirements, but the Open Bench is 1/3 the price of the saleae and is open source.
The cons are less mature software and only 24kpoints or so, as opposed to millions for the Saleae Logic. The latter might be a significant advantage here, since it would allow you to sample at a reasonable sample rate for a long time. I don't think any affordable scope has the necessary amount of sample memory (say 300kS/s * 30s = 9Msamples).

Note that a logic analyzer will only distinguish between < logic threshold or > logic threshold, not sure if that's enough for this application. The input voltage is also usually about 5V max.

A DIY solution would probably be doable, but is likely to cost a lot more time if you don't have much experience, and costs may even exceed the $150 or so for a USB based logic analyzer.
 

Offline Gearbreaker

  • Contributor
  • Posts: 17
Re: Wirelessly viewing an oscilloscope waveform?? HELP!!!
« Reply #28 on: October 02, 2010, 02:50:44 pm »
Thank you for the input.  All things considered I am back in favor of the Saleae.  I've done some research and if I needed a project of something to experiment with the open source would be interesting.  I really need to concentrate on the project at hand so there is much to be said for the plug and play capability of the Saleae.   The Saleaes number of "points" or I'm not sure if it's right to call it the "Bit Rate" certainly would be an advantage too. 

I have certainly abandoned the idea of a scope for this project.   I was barking up the wrong tree when I started thinking scope.  Because I had been using a non storage scope to develop the circuit, I led myself down the path of thinking I needed a storage scope to monitor the system in operation.  Also, when it comes to monitoring circuitry while on a motorbike I think simplicity is a good thing.

$150 really isn't much to spend on a tool that is necessary to develop a new product too.

I"m still open to thoughts or suggestions.  Thanks to all again.  Chris.


im not sure if it meets your requirements, but the Open Bench is 1/3 the price of the saleae and is open source.
The cons are less mature software and only 24kpoints or so, as opposed to millions for the Saleae Logic. The latter might be a significant advantage here, since it would allow you to sample at a reasonable sample rate for a long time. I don't think any affordable scope has the necessary amount of sample memory (say 300kS/s * 30s = 9Msamples).

Note that a logic analyzer will only distinguish between < logic threshold or > logic threshold, not sure if that's enough for this application. The input voltage is also usually about 5V max.

A DIY solution would probably be doable, but is likely to cost a lot more time if you don't have much experience, and costs may even exceed the $150 or so for a USB based logic analyzer.
 

Offline TheDirty

  • Frequent Contributor
  • **
  • Posts: 440
  • Country: ca
Re: Wirelessly viewing an oscilloscope waveform?? HELP!!!
« Reply #29 on: October 02, 2010, 07:06:02 pm »
I am actually not measuring any engine parameters, it is a propritary braking system that I am developing.
Standard automotive dataloggers aren't limited to engine parameters.  Like the DL-32 linked, it has some specific engine logging parameters, but otherwise everything is just generic datalogging.  It's meant for any and all sensors that can be used for sensor logging for whatever you are doing.  It's quite nice for doing a full log of all parameters on test runs with suspension travel sensors, traction control, torque or frame angle, accelerometer/gyro.  Match it up with a time synced camera's on the motorcycle and you can really watch what is happening.
Mark Higgins
 

Offline Gearbreaker

  • Contributor
  • Posts: 17
Re: Wirelessly viewing an oscilloscope waveform?? HELP!!!
« Reply #30 on: October 03, 2010, 04:23:39 am »
Mark,   I'll look more closely at DL-32 and let you know if it is the avenue I go with.  I am always open to suggestions.  Thanks again.  Chris.


I am actually not measuring any engine parameters, it is a propritary braking system that I am developing.
Standard automotive dataloggers aren't limited to engine parameters.  Like the DL-32 linked, it has some specific engine logging parameters, but otherwise everything is just generic datalogging.  It's meant for any and all sensors that can be used for sensor logging for whatever you are doing.  It's quite nice for doing a full log of all parameters on test runs with suspension travel sensors, traction control, torque or frame angle, accelerometer/gyro.  Match it up with a time synced camera's on the motorcycle and you can really watch what is happening.
 

Offline qno

  • Frequent Contributor
  • **
  • Posts: 422
  • Country: nl
Re: Wirelessly viewing an oscilloscope waveform?? HELP!!!
« Reply #31 on: October 03, 2010, 07:45:41 am »
Have you checked the USBEE products?


http://www.usbee.com/

They have small devices you can connect to a laptop.
Most important, it comes with software.
Why spend money I don't have on things I don't need to impress people I don't like?
 

Offline Gearbreaker

  • Contributor
  • Posts: 17
Re: Wirelessly viewing an oscilloscope waveform?? HELP!!!
« Reply #32 on: October 06, 2010, 09:36:56 pm »
Mark (and all),

Thank you all very much for your input.  I ordered the Saleae today and after putting it to the test I'll post what happens.  I couldn't have made an educated decision without everyones thoughts.  I'm actually learning to like learning again.  Chris.



You certainly don't need a scope for this.  If you are able to run on a dyno or if you need specific load, a load cell dyno, that parallel port hack would work.  If you could get a laptop with a hardware parallel port, that would work.

Thinking in terms of 'sampling rate' with a microcontroller solution isn't the right approach.  I simple 16 bit timer and some input triggers would capture everything without using up even 1% of its processing cycles and technically the same sample rate as the clock rate.  The hardest part would be just write out to any EEPROM or Flash.  I've never used one, but I imagine you could do it pretty easily with an Arduino and some type of SD Card shield.

It sounds like a plug and play solution is what is being looked for here.  This is simple on/off data, so a logic analyzer would work here.  Something like the Saleae, or there's that open source one, the Open Logic Sniffer.

Unfortunately almost all automotive specific data loggers measure duty cycle or frequency, but I think you are looking for a higher resolution datalog.  Something that will show precise on and off times relative to the other channels.
If not, the Innovate DL-32 is a good on-board datalogger.
http://www.innovatemotorsports.com/products/dl_32.php
 

Offline TheDirty

  • Frequent Contributor
  • **
  • Posts: 440
  • Country: ca
Re: Wirelessly viewing an oscilloscope waveform?? HELP!!!
« Reply #33 on: October 07, 2010, 02:01:59 am »
Watch out you don't connect it directly to a 12v signal by accident.  You'll need some kind of level converter if you want to do that.  A simple resistor divider will work, but give it some room. I've found motorcycle power to be very noisy.  More so than car systems.
Mark Higgins
 

Offline Gearbreaker

  • Contributor
  • Posts: 17
Re: Wirelessly viewing an oscilloscope waveform?? HELP!!!
« Reply #34 on: October 07, 2010, 03:50:35 am »
Mark,

Yes, I will build a small interface board to clamp the inputs even though the pic is running @ 5 volts.  There still can be transients running around the bike, good point.  Now that you mention it, the transients could be the root of the problem.  If the logic probe sees them I'll have to watch for them with a triggered sampling scope to better understand what is needed to correct the problem.

Thanks again.  Chris.


Watch out you don't connect it directly to a 12v signal by accident.  You'll need some kind of level converter if you want to do that.  A simple resistor divider will work, but give it some room. I've found motorcycle power to be very noisy.  More so than car systems.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf