question on External Trigger for OpenBCI Cyton, location in recording ?

Comments

• wjcroft Mount Shasta, CA

  October 2021

  Hi Pluto,

  The different 'Board mode' trigger recording modes, replace the Accelerometer data normally stored in the three Aux channels.

  https://docs.openbci.com/Cyton/CytonSDK/#board-mode

  Richard @retiutut, can you explain in what cells the 5 digital mode values are stored in the CSV recording file? I don't think this is documented. The recording header does show the locations of the 3 analog mode pins values, but unclear where the digital mode values are stored. Or does the recording file header change when in digital board mode?

  I don't think Pluto is intending to access Brainflow API directly, but rather to just pick these triggers out of the recording. If he was using the API, there are probably calls to get the analog and digital mode values.

  William
• pluto mars

  October 2021

  Hi Wjcroft,
  Yes, I am aware of the different board-modes, have tried it out with SDK as well, but I need it to be working with OpenBCI GUI, so I went ahead with testing it with GUI.

  Regarding Brainflow API , I am not using Brainflow API directly. I am instead using OpenBCI GUI Digital Read widget.
• wjcroft Mount Shasta, CA

  October 2021

  @pluto said:
  Hi Wjcroft,
  ...
  Regarding Brainflow API , I am not using Brainflow API directly. I am instead using OpenBCI GUI Digital Read widget.

  In the default real-time streaming operation mode, the GUI is accessing the Cyton board via Brainflow. And the channels, and aux channels are being shown in the CSV as reported by Brainflow. I assume you know that the GUI can also convert the SDcard hex files BACK INTO normal CSV files, with the conversion feature.

  The SDcard hex format is shown here, when the accelerometer is being used, the default mode:

  https://docs.openbci.com/Cyton/CytonSDCard/#data-logging-format

  The normal data channels are 24 bits in size, and shown as 6 hex digits. The three 'Aux' channels are only 16 bits, and shown as 4 hex digits. When you press and release the button, you should see a bit turn on and off in the Aux digits.

  In your hex recording, do you see the Aux channels on EVERY line? That is how they are being reported in live streaming mode into the CSV. The example at the link above shows the Accel sampling at 50 Hz, whereas the normal channels are sampling at 250 Hz. When Digital Board Mode or Analog Board Mode is turned on, the Aux channels are sampled also at 250 Hz. So you should see 3 Aux values on each line of the SDcard recording, along with 8 channel values.

  William
• retiutut Louisiana, USA

  October 2021

  There is no longer a conversion feature in GUI v5 for SDCard -> Readable TXT. The GUI reads the SD card files directly.
• pluto mars

  October 2021 edited October 2021

  @wjcroft said:

  @pluto said:
  Hi Wjcroft,
  ...
  Regarding Brainflow API , I am not using Brainflow API directly. I am instead using OpenBCI GUI Digital Read widget.

  In the default real-time streaming operation mode, the GUI is accessing the Cyton board via Brainflow. And the channels, and aux channels are being shown in the CSV as reported by Brainflow. I assume you know that the GUI can also convert the SDcard hex files BACK INTO normal CSV files, with the conversion feature.

  The SDcard hex format is shown here, when the accelerometer is being used, the default mode:

  https://docs.openbci.com/Cyton/CytonSDCard/#data-logging-format

  The normal data channels are 24 bits in size, and shown as 6 hex digits. The three 'Aux' channels are only 16 bits, and shown as 4 hex digits. When you press and release the button, you should see a bit turn on and off in the Aux digits.

  In your hex recording, do you see the Aux channels on EVERY line? That is how they are being reported in live streaming mode into the CSV. The example at the link above shows the Accel sampling at 50 Hz, whereas the normal channels are sampling at 250 Hz. When Digital Board Mode or Analog Board Mode is turned on, the Aux channels are sampled also at 250 Hz. So you should see 3 Aux values on each line of the SDcard recording, along with 8 channel values.

  William

  Hi William and retiutut,
  Thanks a lot for your help, I could see a bit turn on / off on AUX2 channel in the logs of SD Card. I observed the same before, but was waiting for confirmation.