If you are up for an EEG experiment which requires offline recording – for example, record EEG in the woods where there is no internet connection, so you’re recording EEG on an SD card; Good news – you are in the right place! In this blog, we will walk you through a way to set up TTL in Neurobs Presentation software, using cable triggering and Smarting PRO mobile EEG.
Smarting Pro supports TTL input of 1 bit. It is a cable that is plugged, on one side, into the amplifier (as an audio jack of 2.5mm) and on the USB port of a computer on the other side. Below you will find an example of setting up TTL in Neurobs Presentation.
- Windows 10, 64bit (in this example we used Windows but check if it applies to other platforms)
- Install drivers for TTL, download here.
- The TTL cable that Smarting Pro uses is this one.
- Install Neurobs Presentation
You should have an experiment scenario already made in Neurobs Presentation or you can use this simple one (mbt sound example). Note that the experiment file (.exp) keeps the path of the computer it is saved on, and the ports it used. To solve this problem, just save it as a new experiment with Save As in Presenter. But before saving, make sure you have changed the Port Settings in the Presenter, as follows.
Then go to Presentation->Settings, Add an OUTPUT Port, because you are sending triggers from the computer to the EEG amplifier. Note that this applies to any other output (cable) using serial port, not only TTL.
After you have filled in the values like in the Figure above, just click on Close.
Some useful info about setting the ports in Neurobs Presentation can be found on their website: Output Port Settings, Event Port Output
Finally, if you want to use the demo examples from Presentation, like the well-known N-Back task, simply add the port as indicated earlier, and Save As new experiment file (it will modify the .exp file with the correct port and path).
TTL is “physically” marked onto the EEG data with minimal delay and can be recorded directly onto the SD card of the amplifier together with the EEG. Additionally, they can be both sent together back to the computer (mbt Streamer) via Bluetooth. In that case, open and connect the mbt Streamer to allow receiving EEG streams on your computer (capturing bluetooth packets). You can also see TTL triggers marking EEG signals in real-time on mbt Streamer. TTL protocol facilitates the integration of embedded systems e.g. it could send events from the Arduino board (using a serial communication).
This way you can see how TTL markers, once physically integrated into the EEG, are streamed along with the EEG signals through bluetooth and converted into LSL streams.
Let us know how it goes and if you have any questions feel free to reach out to us on our contact page.
*Conclusion written by mbt team