Cyton to Android via Bluetooth LE

NaughtiusMaximus · November 2018

Hi All (and William),

I have a Ganglion, which works great. But I am thinking of getting a Cyton because I need the 250 Hz sampling rate. Here are my questions:

(1) Is there Android code yet for the Cyton?

(2) I'd like to stream over Bluetooth LE. I only need one or two channels, so does turning off all the other channels ACTUALLY stop the data from being transmitted to an Android device (to reduce bandwidth need)? Seems to say so here http://docs.openbci.com/OpenBCI Software/04-OpenBCI_Cyton_SDK:

"Turn Channels OFF

1 2 3 4 5 6 7 8
These
ASCII characters turn the respective channels [1-8] off. The channel
will read 0.00 when off during streamData mode. These commands work in
and out of streamData mode.

returns none, there is no confirmation."

(3) Are there any specifications on the power consumption of the Cyton?

Thanks,

Max

wjcroft · November 2018

Max, hi.

You already have the Ganglion. It is capable of higher sample rate with the addition of the Wifi Shield. Then you would stream over Wifi, not Bluetooth.

re: Cyton over Bluetooth. Unfortunately, no Cyton and it's dongle use a special Bluetooth protocol from Nordic, called Gazelle (GZLL), that optimizes the radio bandwidth necessary for high data rates (~ 100K bits/sec). Cyton does not use BLE. Turning off channels does not remove them from the data packets.

AJ did some custom firmware that will let Cyton use BLE at reduced number of channels (2, but only 125Hz). See this,

http://openbci.com/community/cyton-ble-code-now-in-alpha/

I suggest your easiest route is to add a Wifi Shield to your Ganglion. Or you could also use a shield with Cyton.

Regards,

William

PS a longer term solution is in progress on a future board. To use the ESP32 radio, which supports Bluetooth 3.x as well as 4 (BLE). Bluetooth 3 has a built in serial port protocol that can stream much faster than the limitations of BLE.

https://www.google.com/search?as_q=cyton+power+ma

NaughtiusMaximus · November 2018

Hi William,

Thanks for your quick response. You have been incredibly helpful over the last few weeks!

We actually need a sampling rate of a multiple of 125 Hz, thus AJ's solution may work!

Best regards,

Max

wjcroft · November 2018

EEG can be resampled via various algorithms. Typically oversample first then interpolate back down.

https://www.google.com/search?q=eeg+resample

Thus Ganglion at 400 could be resampled to 250.

NaughtiusMaximus · November 2018

Hi William,

Is AJ Keller still involved? He seems to have vanished. His Twitter account and Push The World LLC don't exist anymore. The last comment from him on Gitter (https://gitter.im/OpenBCI/OpenBCI_NodeJS?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) was about a year ago.

Thanks,

Max

wjcroft · November 2018

https://github.com/andrewjaykeller

https://twitter.com/andrewjaykeller

https://www.neurosity.co/

You can also reach him by clicking on his at-sign name, and using the Message button. AJ @pushtheworld.

Cyton to Android via Bluetooth LE

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