Adding marker to the file when recording with the SD card

jcyhuangjcyhuang Philadelphia

Hello team,
We are thinking of using 16-channel Cyton+Daisy with the SD card for a higher sampling rate. However, we are having problem with inserting a marker with the python script.

Prior to using a SD card, we have been using the function board.insert_marker(markerValue) from the Brainflow API to insert the marker in column 31 (please see the screenshot below).

However, when we start using a SD card, our output only consists of 19 columns, which I believe column 0 is the row#, 1-16 are the EEG data, and 17-19 are the AUX data

My question is, how can we create a marker column similar to column 31 from the first screenshot to the SD file? Is there a way for us to insert a marker to the output from the SD card? I found some literature on using the marker mode (https://docs.openbci.com/Cyton/CytonSDK/). We tried setting the board mode to /4 with the Brainflow function config_board('/4') then send marker by doing config_board('`9'). However, the approach has not seemed to work. Would appreciate if the dev team has any suggestions on this.

Comments

  • wjcroftwjcroft Mount Shasta, CA

    JC, hi.

    The last three columns in the SD card hex file, are the "Aux channels". By default these carry the Accelerometer x,y,z values. But they can instead be configured (using "board mode" SDK commands), to record the Dxx pins on the top board headers. And can be put in either 'analog' or 'digital' recording mode.

    The 'best' timing synchronization method is with "external trigger" / sync techniques, which have much improved accuracy over the "marker mode" feature in the SDK. As far as I know, very few customers use this marker mode, for exactly this same reason.

    https://docs.openbci.com/Cyton/CytonExternal/

    It seems unlikely that the "marker mode" status can be recorded to the SD card, as there is no space allocated to record such.

    Regards, William

  • jcyhuangjcyhuang Philadelphia

    Thank you as always @wjcroft.
    I think we decided to just stop/start the data streaming in place of the trigger, since we are only marking the beginning and end of the stimuli (i.e., the video).

  • @wjcroft said:
    JC, hi.

    The last three columns in the SD card hex file, are the "Aux channels". By default these carry the Accelerometer x,y,z values. But they can instead be configured (using "board mode" SDK commands), to record the Dxx pins on the top board headers. And can be put in either 'analog' or 'digital' recording mode.

    The 'best' timing synchronization method is with "external trigger" / sync techniques, which have much improved accuracy over the "marker mode" feature in the SDK. As far as I know, very few customers use this marker mode, for exactly this same reason.

    https://docs.openbci.com/Cyton/CytonExternal/

    It seems unlikely that the "marker mode" status can be recorded to the SD card, as there is no space allocated to record such.

    Regards, William

    Hello, the data of digital channels in the CSV data we have collected is in "other". What I want to ask is how to use the board mode to configure the last three columns instead of the accelerometer when using the SD card. If there is a way to do this, please help me. Thank you very much!

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