Openbci_gui: GUI impedance buttons fail on Mac standalone 4.0.3, work with standalone 3.3.2

[wjcroft]

Problem

See description and video here,

https://openbci.com/forum/index.php?p=/discussion/1961/impedance-measuring-issue-with-openbci-gui-4-0-3-standalone-osx

In short, pressing the ohm button on 4.0.3 standalone, results in some temporary numbers shown for impedance, but those quickly ramp down until ZERO ohms is shown. And does not vary from zero after that. Works fine in 3.3.2.

Expected

Same behavior as 3.3.2

Operating System and Version

macOS

GUI Version

4.0.3 fails, 3.3.2 works

Running standalone app

Standalone

Type of OpenBCI Board

Cyton

Are you using a WiFi Shield?

No

[retiutut]

The video is incredibly helpful!!! Might look into this later.

[krisztian-hofstadter-tedor]

@retiutut
let me know if you need anything else from me - thanks! k

[krisztian-hofstadter-tedor]

today I installed Mojave on a partition and tried reading impedance with version Jan 2019 and Nov 2018 of the standalone. I tried with 1) the Apple Driver, 2) the recent FTDI and the earlier version of the FTDI suggested in the documentation: https://www.ftdichip.com/Drivers/VCP.htm

I tried the FTDI buffer size fix as well (http://docs.openbci.com/Tutorials/10-Mac_FTDI_Driver_Fix) but still the same issue.

The June 2018 version reads of the impedance still.

I shall try the Processing SDK next and try another computer as well.
thanks, k

[retiutut]

@krisztian-hofstadter-tedor I'm using Mojave on my primary Mac I use to edit GUI code.

[retiutut]

I don't see any problems with the code that calculates the impedance. As seen in DataProcessing.Pde:

  //compute the electrode impedance. Do it in a very simple way [rms to amplitude, then uVolt to Volt, then Volt/Amp to Ohm]
  for (int Ichan=0; Ichan < nchan; Ichan++) {
    // Calculate the impedance
    float impedance = (sqrt(2.0)*dataProcessing.data_std_uV[Ichan]*1.0e-6) / cyton.get_leadOffDrive_amps();
    // Subtract the 2.2kOhm resistor
    impedance -= cyton.get_series_resistor();
    // Verify the impedance is not less than 0
    if (impedance < 0) {
      // Incase impedance some how dipped below 2.2kOhm
      impedance = 0;
    }
    // Store to the global variable
    data_elec_imp_ohm[Ichan] = impedance;
  }

So, maybe one of the inputs are not within normal limits and produces the false reading.

[krisztian-hofstadter-tedor]

many thanks Richard.
which FTDI driver do you use?
also, when you say 'I use to edit GUI code', do you mean you run you have the OpenBCI_GUI running in the Processing app instead of running the standalone app?
thanks! k

[retiutut]

I use FTDI 2.3, which supports OS X 10.9 and up.

I typically edit and run the GUI using Processing or Atom. The standalone app is packaged using Processing.

[krisztian-hofstadter-tedor]

thank you.

did you do the 'fixing FTDI InBufferSize' tweak explained in the docs in you Mojave?
'http://docs.openbci.com/Tutorials/10-Mac_FTDI_Driver_Fix'

didn't know you can run OpenBCI in Atom - I'll ingestive.
thanks, k

[retiutut]

I'm not sure about the FTDI fix, and I may still be using 2.2.18....

But I think I may have found the problem:

• GUI possibly not sending valid command to Cyton to check Impedance values

In BoardCyton.pde, writeImpedanceSettings() changed from GUI v3 to GUI v4. This function is called when the Impedance Toggle is pressed for all channels on Cyton

@andrewjaykeller is there possibly a mismatch between the Hub and the GUI related to this issue?

[krisztian-hofstadter-tedor]

thanks Richard. this is good news.
next time your USB dongle is in your computer, could you please check your FTDI (in Mojave)?

kextstat | grep FTDI
in terminal what I use for this.

then I could know for sure - many thanks!

[retiutut]

kextstat | grep FTDI

in terminal what I use for this.

Thanks!
com.FTDI.driver.FTDIUSBSerialDriver (2.4.2)

[retiutut]

In BoardCyton.pde, writeImpedanceSettings() changed from GUI v3 to GUI v4. This function is called when the Impedance Toggle is pressed for all channels on Cyton

@daniellasry @andrewjaykeller There is a success case in processImpedance() in InterfaceHub.pde that never prints to console: output("Success: Impedance " + action + "."); I'm not sure the error code cases are being called either.

When toggling Impedance with Cyton, I'm not sure the GUI is receiving a response code from the Hub.

[retiutut]

@krisztian-hofstadter-tedor

Got it!!! 🔥 🔥 🔥

[retiutut]

@daniellasry @krisztian-hofstadter-tedor @wjcroft

https://github.com/OpenBCI/OpenBCI_Hub/pull/76

https://github.com/OpenBCI/OpenBCI_GUI/pull/429

Version pushed to 4.0.4

[krisztian-hofstadter-tedor]

thanks Richard, I'll try asap!

[daniellasry]

Hey @krisztian-hofstadter-tedor , I just posted a new release of the GUI: v4.0.4. It includes Richard's fix. Please give it a try, and let us know if it's behaving as you expect. Thanks!

[krisztian-hofstadter-tedor]

thanks @daniellasry and @retiutut, working again :)
https://youtu.be/XHSBRGN8os4