Android tablet s Oscilloscope

[tpajet]

I have an Android tablet and I'd like to know if there are any ideas about using it a an oscilloscope. I've seen a couple DIY projects, one is a bluetooth deal, but they are all very limited on voltage input or analog bandwidth. I would think that with the USB scopes that are out there today that there would be a good option for a tablet, but I just can't seem to find much.

 

[donkey]

there is probably a reason for that.
think of it this way when I get my laptop, I plug in the USB, plug in power and run the oscilloscope for hours on end.
on a tablet if I plug in my oscilloscope I won't have power... so Bluetooth is the best option. My thinking is you find one for like a raspberry pi, then use a wifi for it to send data to your tablet.

 

[shumifan50]

Android devices are typically not designed to do fast high volume data processing, so trying to run an oscilloscope on such a device would be very limited IMHO. Most mobile devices are more concerned about battery life than performance.

 

[davenn]

Android devices are typically not designed to do fast high volume data processing, so trying to run an oscilloscope on such a device would be very limited IMHO. Most mobile devices are more concerned about battery life than performance.

I doubt that that is the problem. Most Android phone/tablets have excellent microprocessors in them these days. Anything from 1GHz to 2GHz speed. They can easily handle high data volume HD video. And the A to D conversion and displaying of a couple of squiggles on a scope screen would require minimal processing in comparison.

I was using computers for ADC sampling and displaying when processor speeds were well below 100 MHz

cheers
Dave

 

[shumifan50]

@Dave
Have you compiled anything on a Raspberry Pi? It is frighteningly slow, read unusable for compilation. HDMI is done in hardware. The USB master is totally unreliable; and I tried a variety of SD Cards, hard disks and USB drives; all corrupted within weeks.
None of my tablets support master mode, only slave, so that could be the first hurdle.

 

[Gryd3]

@Dave
Have you compiled anything on a Raspberry Pi? It is frighteningly slow, read unusable for compilation. HDMI is done in hardware. The USB master is totally unreliable; and I tried a variety of SD Cards, hard disks and USB drives; all corrupted within weeks.
None of my tablets support master mode, only slave, so that could be the first hurdle.

Depends what you want to compile. It's a very slow processor, but how much CPU could it possibly require to poll oscilloscope values?
I've been running my PI for a couple months with 100% uptime and have had no issues as of yet.

Also, you need an adaptor to use your Android device as a host. (And a specific version)
http://developer.android.com/guide/topics/connectivity/usb/host.html


Also : http://www.zeitnitz.de/Christian/scope_en

 

[tpajet]

It sounded like a cool idea, but after looking this over a bit I'm thinking a regular digital scope is the way to go. I'm still just a bit surprised that this is not more prevelant.

 

[davenn]

@Dave
Have you compiled anything on a Raspberry Pi? It is frighteningly slow, read unusable for compilation. HDMI is done in hardware. The USB master is totally unreliable; and I tried a variety of SD Cards, hard disks and USB drives; all corrupted within weeks.
None of my tablets support master mode, only slave, so that could be the first hurdle.

we were talking about fast android tablets, not slow raspberry pi's
don't sidetrack the issue


D

 

[shumifan50]

jeeze sorry.
As in my previous post none of my TABLETS support USB master mode.

 

[donkey]

ok so we all agree USB is not the answer.
how about using the audio jack? it has a microphone input, could you not simply code over that?
the problem I have is that a good tablet will set you back $400. I really don't want to plug something into it that may fry it. Bluetooth or wifi is a great option though.
anyway if you ever create something let us know

 

[Gryd3]

USB would be a very poor answer if you want support on multiple devices...
Using the audio jack is possible... and it has been done before on PC : http://www.zeitnitz.de/Christian/scope_en
You will run into limitations though, as there are typically coupling capacitors in use that will not allow a scope to operate with DC. It may also cause distortion on the captured signal if the frequency is too low.
You will also require a method to protect the device you use with the probe, but that would be a requirement regardless of the approach you take.

*You may be able to use both methods as a solution if you can find a USB audio capture device with a very high sample rate... Many (but not all) devices support USB sound cards without the need for additional drivers.

An alternative solution could very well be bluetooth... but the only viable way I see this working is if your bluetooth scope only passed the resulting image to the tablet as I am doubtful that the bandwidth would support sending the actual sampled data at a quick enough rate... (But it's highly possible I'm wrong, as bluetooth data transfer speeds can support high data transfer rates for files.)

 

[donkey]

I wasn't thinking of making the the MIC line for sending the readings through, use it as a data line. use a secondary micro controller to receive all the data from the probes then convert it to a data line that the tablet reads over the mic input and translates into a grid.
sampling rate would be atrocious for multiple lines but its could be done.
I still say WIfi all the way though. use something to read it send it over wifi and the tablet puts it into a pretty little program you can play with

 

[Gryd3]

I wasn't thinking of making the the MIC line for sending the readings through, use it as a data line. use a secondary micro controller to receive all the data from the probes then convert it to a data line that the tablet reads over the mic input and translates into a grid.
sampling rate would be atrocious for multiple lines but its could be done.
I still say WIfi all the way though. use something to read it send it over wifi and the tablet puts it into a pretty little program you can play with

Oh hell... if your using the external device to do the sampling and processing then you could easily get away with wifi or bluetooth... I'm sure you could get away with using the audio-in as a type of data line if you can trick a program into using it like on of those irritating 56.6k modems...
I thought you wanted real-time display on the tablet... but if your fine with near real-time of a zoomed out capture updated once a second you have tons of options.

 

[Gryd3]

These things use the audio jack in tablets to operate
http://9to5mac.com/2014/07/30/squar...secure-mobile-credit-and-debit-card-payments/
You can too

 

[cjdelphi]

Android tablets should support usb on the go powering the oscilloscope, I have a quad 1.4ghz in my tablet so cpu power is barely even an issue

It's possible via usb otg.

 

[Gryd3]

Android tablets should support usb on the go powering the oscilloscope, I have a quad 1.4ghz in my tablet so cpu power is barely even an issue

It's possible via usb otg.

The next question is hardware support then.
USB on the go is supported by many, but not all devices. I am unsure if you would need native support for the device, or if you can build an 'app' that can support it... I have yet to look into that kind of security feature in Android.