A user in the OpenBCI forum found a solution to sample data from multiple Ganglion boards:
https://openbci.com/forum/index.php?p=/discussion/2505/multiple-ganglion-boards#latest
www.openbci.com moderator William Croft about this topic:
«In general, for example with EEG, you cannot really using multiple boards on the same person. Because the sample times are not synchronized. Realize that with Cyton, when used with a Daisy expansion, all 16 channels are sampled at the same instant.»
Peter Gamma from www.petergamma.org about this topic:
- For a professional solution all channels of all Ganglion boards needed to be sampled at exaclty the same time.
- This is not possible with the current architecture of OpenBCI.
- It could by solved by:
- daisy chain algorithms for the ADS1299 chip.
- or by an external clock for the ADS1299 which synchronizes the chips.
- Both of these solutions would require a fimware modification of OpenBCI
- And I do not know if would also require a hardware modification, a direct connection between the Cyton boards for transmitting the clock signal as fast as possible.
The effort for such a solution seems to be big. If it would be worth doing, I suppose someone would already have done it. I think it is easier at that point to start a new project based on InfluxDB:
- devices from mBrainTrain offer EEG devices from 24 channels up to 64 channels, but they are expensive and not open source soft- and hardware.
- The Meditation Research Institute Switzerland (MRIS) found out that heart rate and breath rate are sufficient for meditators who want to practice with a technology assisted device.
- A Fenix 6 offers these parameters, but unfortunately is basically not suitable for scientific applications.
- To build up a new device with a 3 channel ECG device, respiration rate estimation and a spirometer would be a good solution for us personally.
- This requires only 4 channels.
- This could be solved with OpenBCI Ganglion.
- But meditation research without brainwaves is according to our own little experience not very satisfying.
- For us personally to start a new project based on InfluxDB seems currently more interesting than based on the ADS1299.