Do you know if I can connect 2 or more boards to the same dongle, and stream data accordingly in a way EEG signal from several individuals are synced ?
No, the anti-static bag that your mainboard is shipped in, shows a channel number. This matches the channel number programmed into the dongle. If you use multiple boards they must be on separate channels, streaming to their matching dongles. The RFduino data link is not fast enough to handle multiple boards at once.
The LSL LabStreamingLayer might help you synchronize streams, but there may still be substantial jitter since the sample rate clocks are not crystal controlled. Thus sample rate can vary, e.g 250 sps, 251 sps, 249 sps, etc.
I believe when multiple boards are ordered at once, the channel numbers are always chosen so as to not interfere with each other. It's possible that the order fullfillment center also logs the channel numbers in use by each customer.
Comments
See this related thread,
http://openbci.com/forum/index.php?p=/discussion/364/run-2-openbci-boards-simultaneously-to-get-16-channels
The LSL LabStreamingLayer might help you synchronize streams, but there may still be substantial jitter since the sample rate clocks are not crystal controlled. Thus sample rate can vary, e.g 250 sps, 251 sps, 249 sps, etc.
http://openbci.com/forum/index.php?p=/search&Search=lsl
William
I am glad I asked before buying the boards. Now I can ask for different channels when ordering :-)
Have a good day!
Thomas