Channel order in GUI and Brainflow (Confused)
ihgumilar
Auckland
Dear OpenBCI experts,
1. In OpenBCI (I am using 16 channels), there is N1P - N8P . When I tried to use GUI, for example, channel 1 that is displayed in Grey in GUI is actually related to N8P (Grey) Cyton board- C3 in this case. What I am asking is the numbering order comes backward N8P - N1P instead of N1P- N8P ?
2. Does that backward system also apply to the brainflow (Does column 1 represent N8P in Cyton board ?
This is a bit confusing for me. It seems to be contradicting with the documentation on the website which says "Connect top pins N1P through N8P on the Daisy module to another set of HPTA cables, shown below. These pins will be channels 9-16." In fact, when I looked at the GUI, it is actually N8P - N1P (Daisy board) **for **channels 9-16
Thanks
Ihshan
Comments
Ihshan, hi.
I'm having a hard time understanding your question. You can always verify the identity of your channel in the GUI. When you touch or tap on a pin or electrode, that channel will jump on the time series. They are not "numbered backwards"
The documentation section you quote does have a small typo but the photo is correct. The text reads: "Connect top pins N1P through N8P on the Daisy module to another set of HPTA cables, shown below. These pins will be channels 9-16." No, actually the HPTA cables always connect to the 'bottom' pin row on both mainboard and Daisy.
William
Hi William,
Thank you for your reply.
I look at the GUI, for example, Channel no. 2 (violet) in GUI, the time series jumped when I tapped electrode T3, which is plugged into N7P (Cyton board). So, I thought channel no.2 in GUI always refers to pin N2P in board (in this case, (main) cython board) . But, in fact, it is not right ? if not, how do we know the order of the channels, which I need for giving a proper name of my data.
Is the order of the channel always starting with whatever electrode that is connected to N1P ?
Btw, Yest, I connect all of the cables to the "botom" pin row on both mainboard and daisy
Thanks
It sounds like your electrodes may not be correctly wired to the channel pins. Channel pins are not reversed. I don't know how to explain what you are seeing with channel 2 and channel 7, but it does not happen to anyone else I am aware of. What headset or cap are you using?
The default head map to channel number mapping is shown on this thread,
https://openbci.com/forum/index.php?p=/discussion/3092/map-connecting-electrode-cap-positions-to-channels-resolved
https://openbci.com/forum/index.php?p=/discussion/1087/connecting-mark-iv-to-cyton-including-daisy-board/p1
Regards, William
I use this one https://shop.openbci.com/products/openbci-eeg-electrocap-kit
Trace out by hand following the wires, including the touchproof adapter, each electrode from the cap to the Cyton or Daisy pin. Another option is to use a multimeter / continuity checker. It is remotely possible that the cap wire tags / labels were switched or applied wrong (but unlikely). This procedure will verify each channel.
If you want your channel mapping to match the GUI head map, the diagram on this page shows that map and coloring.
https://openbci.com/forum/index.php?p=/discussion/1087/connecting-mark-iv-to-cyton-including-daisy-board/p1
Finally, touch each cap electrode one by one and verify that the correct channel jumps in the GUI.
Please comment once you have gone through these steps.
Regards, William
Hi William,
Thank you for your patience and sorry for my silly mistake in looking at cable and electrode mistakenly.
Everything works fine by now. N1-8P (Cython board) for Chan.1-8 & N1-8P (Daisy board) for Chan.9-16.. Some of you who may have the same issue. Just ignore the colour that you see in GUI since it is not always related to the same colour that you use in your cable.
Thanks
Ihshan