Flea-Scope™ USB Oscilloscope, Logic Analyzer, and more ($18, 18 Msps, WebUSB)

[rich t]

Hi all,

I've been working on this for about a year and finally got it into production -- it's a super-simple and easy-to-use USB oscilloscope, logic analyzer, and waveform generator that is controlled by a web-page -- with no software install required!  Just open a web-page -- on a computer, tablet, or phone -- and connect to the USB device using WebUSB and you are up-and-running.

The board is basically some life-support and a bit of analog front-end around a fast MCU -- the PIC32MK0512GPK064, with 5 interleaved ADCs running together!

It's also completely open-source, so you can build one yourself if you want and dive into the inner workings -- check out:

https://hackaday.io/project/192598-flea-scope-usb-oscilloscope-18-18-msps-webusb

The full User's Guide with specifications (and a "how it works" section) is here:

https://rtestardi.github.io/usbte/flea-scope.pdf

I am dreaming of getting this into high-schools to help kids build technology again -- not just assemble prefab components -- my first oscilloscope cost $400 and had basically the same specs as this!  It's likely good enough for most things kids can do with a solderless breadboard or wire wrap!

I also think it's an amazing example of how you can use WebUSB to connect to microcontroller gadgets -- and avoid the whole problem of writing an "app" for a half-dozen different platforms, in different languages, dealing with app stores or driver signing or whatever!  Literally, you just open a web-page and you are up-and-running!

The even cooler thing is you can use a different web-page and log in interactively and reprogram the thing in BASIC and take control of all its pins, turning the MCU into a fully re-programmable embedded systems core!

If you know anyone in education who would want these for their classroom, I have a few hundred extra in hackerbox form -- have the school contact me!

-- Rich

[shabaz]

That looks really nice. Congrats on the product. And great vision that this could be useful for schools and kids.
I'm going to order from Elecrow at least a couple (so that hopefully a couple of kids can show their teacher all about it).

[rich t]

Thanks!!!  The other place I find this useful is for automotive work...  It is nice to finally be able to see things like the crankshaft sensor signal with just a laptop!

[PCB.Wiz]

That's cute.

Did you look at the (very) new dsPIC33A ? - claims 2 x 40 Msps ADC's, 40V/us OpAmps,  and 1.6GHz VCO's, comes in 28/36/48/64 pin packages.
Could be a base for a nice Scope/Generator/frequency counter ?

https://www.microchip.com/en-us/search?searchQuery=dsPIC33A&category=ALL&fq=start%3D0%26rows%3D10

[rich t]

Wow, no, I did not see that one!  And am having trouble finding a real datasheet...

(And the MK/GPK was brand new when I started -- we had to wait until March of this year for production ramp...)

How did you find that?  Might there be one with USB as well?  80 Msps would be amazing -- I could spin the board for that! :-)

The challenge at these rates is you can run out of DMA bandwidth -- I actually had the ADCs working at 20 Msps on MK/GPK, but had to drop it to 18.18 Msps because we ran out of bus bandwidth when I added in digital capture and waveform generation as well.

[PCB.Wiz]

How did you find that?  Might there be one with USB as well?  80 Msps would be amazing -- I could spin the board for that! :-)

https://www.eevblog.com/forum/microcontrollers/dspic33a-new-32bit-dsp!/

Good question, there are part codes suggesting larger parts, but all I can find is brief :

dsPIC33AK512MC206-E/PT  200 MHz, 512KB Flash, FuSa-Compliant, HS-Analog, HS-PWMs, Touch, 64 TQFP 10x10x1mm TRAY

What data rates does the current model manage on USB ?

[rich t]

Oh, the USB on PIC32MK/GPK is slow -- 12 Mbits/sec -- but that really doesn't matter because we set up trigger (there is well under 1us trigger delay) and capture while we're not using USB, and only after we capture data, then we send it over the USB to be displayed by the web-page -- we can get maybe 10 captures/second (with about 2000 points per capture) even with the slow USB, with a decent host, so you get a nicely animated display.

It looks like there is a dsPIC33A curiosity board available for $98, but no hint of parts themselves from microchip direct -- so no real clue about pricing...  I'd love to know if we have to do interleaving to get 40 Msps (interleaving was a pain and a further burden on DMA), or if it "just works"...  These parts are amazing!  (There was an NXP part that went to 80 Msps, but it was BGA-only and very expensive -- so I passed that one by -- PIC32MK/GPK was the best I could find when I started, but the MCU discovery process always seems like black magic to me, especially across vendors!)

[PCB.Wiz]

It looks like there is a dsPIC33A curiosity board available for $98, but no hint of parts themselves from microchip direct -- so no real clue about pricing...

There is web pricing, no idea how valid it is...
eg
DSPIC33AK32MC102-E/M7    114 $2.41
DSPIC33AK512MC506-E/M7   50  $5.64

[rich t]

I currently pay $8.50 in 1000 quantity for PIC32MK/GPK!

Wow!