cee is very handy & works great! quite a bit of noise on the voltage output

35 views
Skip to first unread message

John Hull

unread,
Mar 31, 2014, 1:41:45 PM3/31/14
to nonoli...@googlegroups.com
I just finished a project using cee and it was very handy. Any limitations seemed due to my lack of programming expertise.

One thing I noticed was about 0.5V noise on the voltage output. I disconnected the USB 5V and used an external supply with little change. The noise isn't random. Is it caused by the embedded micro?

Is there any on-going development? I would be very interested in new versions (hardware and software). Please, keep up the good work.

Ian Daniher

unread,
Mar 31, 2014, 2:38:20 PM3/31/14
to nonoli...@googlegroups.com
Hi John!

Thanks for writing, glad you liked CEE! That much noise is very irregular - with what type of load did you use the device? I've observed edge cases on inductive loads where the bandwidth of our control loop couldn't cope with a high frequency inductive node, but that issue materializes as sinusoidal oscillations, not random noise.

As for ongoing development, yes - Kevin and I are both hard at work, with another complete redesign of CEE being released under an open source license under different brand in the not too distant future. If you have specific software features / hardware wish-lists, please share!

Best!
--
Ian


--
You received this message because you are subscribed to the Google Groups "Nonolith Labs CEE" group.
To unsubscribe from this group and stop receiving emails from it, send an email to nonolith-cee...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

John Hull

unread,
Apr 1, 2014, 2:11:17 PM4/1/14
to nonoli...@googlegroups.com
Ian,

the noise is not random. With no load, I scope a voltage output on channel A. I see something like:
-----------!--!----------------!--!--------------!--!------------
The pk - pk of the big spikes is 150mV. The baseline is approx. 50mV. The period of the big spikes is approx 37.6uS, while the space between the spike couplets is approx 5.7uS. The big spikes consist of maybe ten cycles of approx 20MHz. The "noise" on the baseline looks to be approx 100MHz.

I set the voltage using pixelpulse with the default settings. I just imagine this is USB "noise"? Any suggestions would help

As far as additional features - I work mainly with much lower currents - force & measure - in the uA range. 100uA resolution is much to high for me. I could use higher voltages - up to 10V or so - but that is secondary for me.

My biggest challenge is SW. In this last project, I needed to control two pieces of equipment (cee & another) synchronously. I used the REST api, but was a bit overwhelmed trying to bind in the other equipment or move to another scripting language and find an http client to run cee.

In my humble opinion, the hardware nowadays is secondary to the software support. And for us hardware designers who muddle thru the software issues, numerous examples help tremendously.

Thanks for hearing me out
John Hull
Technical Marketing Mgr
NXP Semiconductors


--
You received this message because you are subscribed to a topic in the Google Groups "Nonolith Labs CEE" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/nonolith-cee/ZHcfRBx-cXA/unsubscribe.
To unsubscribe from this group and all its topics, send an email to nonolith-cee...@googlegroups.com.

Ian Daniher

unread,
Apr 1, 2014, 5:18:28 PM4/1/14
to nonoli...@googlegroups.com
Hey John,

Thanks for sharing! Nothing on the board is running close to 100MHz, so I'm guessing EMI / switcher noise coupling in through the power supply? 20MHz or 16MHz may very well be SPI bleed-through, which our next hardware rev (with much nicer silicon) should address. Can you grab data or screenshots? I'd love to see exactly what you've seen.

For microamp scale, you may be able to replace the default 0.07o resistor shunt with a 1ohm sense resistor and change the gain values via http://apps.nonolithlabs.com/edge/editcal. If this is something you're pursuing actively, I can try and assemble a howto in the next weeks.

> My biggest challenge is SW. In this last project, I needed to control two pieces of equipment (cee & another) synchronously. I used the REST api, but was a bit overwhelmed trying to bind in the other equipment or move to another scripting language and find an http client to run cee.

What scripting language were you using, and were you dealing with continuous waveforms, or just taking individual measurements at specific times?

Best!
--
Ian

John Hull

unread,
Apr 1, 2014, 6:35:02 PM4/1/14
to nonoli...@googlegroups.com
Ian, attached a scope shot of the baseline and "big spike" on a 3V DC output. The other is a closeup of the the big spike.

In answer to your question, I'm using AutoIt as a scripting language because I developed an interface to another piece of USB equipment and I can talk to it thru a COM port driver to USB which was already developed (I didn't spend any time to see if Python has a similar thing). But then I was stumped since I couldn't find an http client in AutoIt. I'm not so much interested in grabbing info, but controlling two pieces of equipment simultaneously.

Another request / question. I really like the arbitrary waveform generator. Can I run both channels synchronously? Or does each channel have separate time = 0 depending on when it executes?

BR John




scope_4.png
scope_5.png

James Cameron

unread,
Apr 1, 2014, 6:51:11 PM4/1/14
to nonoli...@googlegroups.com
On Tue, Apr 01, 2014 at 03:35:02PM -0700, John Hull wrote:
> In answer to your question, I'm using AutoIt as a scripting language
> because I developed an interface to another piece of USB equipment
> and I can talk to it thru a COM port driver to USB which was already
> developed (I didn't spend any time to see if Python has a similar
> thing). But then I was stumped since I couldn't find an http client
> in AutoIt. I'm not so much interested in grabbing info, but
> controlling two pieces of equipment simultaneously.

I'm using the cee with connectClientPython [1] and pySerial [2] for
driving USB serial adapters.

1. https://github.com/nonolith/connectClientPython

2. http://pyserial.sourceforge.net/

--
James Cameron
http://quozl.linux.org.au/

Ian Daniher

unread,
Apr 3, 2014, 12:56:44 PM4/3/14
to nonoli...@googlegroups.com
John,

Thanks for the screenshots. I'll look into it.

I'm not so much interested in grabbing info, but controlling two pieces of equipment simultaneously.

I'd highly recommend Python for interacting with multiple pieces of equipment simultaneously. There are libraries for some tek scopes, and pretty much everything else. If you run Windows, the best way to get started might be through Python (x,y) - https://code.google.com/p/pythonxy/wiki/Downloads.

> Another request / question. I really like the arbitrary waveform generator. Can I run both channels synchronously? Or does each channel have separate time = 0 depending on when it executes?

The channels A and B of CEE can have relative phase between the two channels controlled via the API, but not from the user interface. With rev2 on the way, we'll be revisiting this and other UI design thoughts.

Best!
--
Ian

John Hull

unread,
Apr 3, 2014, 4:28:22 PM4/3/14
to nonoli...@googlegroups.com
Thanks for the tips. Between you and James, I should have a good start. Unfortunately, my project / task has ended, so I need to wait for the next application problem to arise.

Is the relative phase documented in the REST page? I don't remember seeing it. For rev 2, I'd like to see the possibility of using cee as a digital source with controlled "setup" and "hold" times. Obviously, the finer the resolution, the better (10ns resolution would work for me)

Also, is there any easy way to scale / change the time base in the UI? That would be very helpful - it allows me to eliminate a scope on my bench for the easy things.

John
Reply all
Reply to author
Forward
0 new messages