NIC can also receive a TTL signal and display it through one of its EEG channels using our TTL Adapter
The TTL adapter only receives binary signals. A TTL signal is always a digital signal. The signal will either produce a logic 0 or a logic 1. Given that the power trigger of the TTL adapter always has to be connected to 5V, the threshold for the input voltage of logic 0 will be in the range 0 and 0.99V and the threshold for the input voltage of logic 1 will be in the range of 3.5V and 5V. If a voltage signal ranging between 0.99V and 3.5V were to be sent into the input of the TTL gate, there would not be a certain response. It can not be predicted to be logic 1 or 0.
This option requires to have a Parallel Port in the computer running the external software. If you don't have a parallel port, you can also install a PCI EXPRESS card emulating a parallel port.
Please see the user manual of our TTL Adapter (attached) detailed information on how to set up the connections.
The following pins of the TTL adapter should be connected to the following pins from the parallel port:
* Pin 1 (Vcc 5V) from the adapter should be connected to any data pin (pins 2-9) of the parallel port. This pin should always be activated at 5V. * Pin 2 (TTL input) from the adapter should be connected to another data pin (pins 2-9) of the parallel port. This pin should only be activated whenever a TTL pulse is sent. * Pin 3 (ground) from the adapter should be connected to any ground pin (pins 18-25) of the parallel port.
The TTL Input should be between (3.3V-5V).
NOTE: the TTL signal will be synchronized with the EEG streaming data and you'll see the TTL pulses in the EEG channel you have used to connect it, but the TTL pulses will not be "written" in the penultimate column of the .easy files as markers. The "detection of the edges" of the TTL pulses in the EEG channel for offline analysis is responsability of the user.
As an example, in the following figure is displayed a connection between the parallel port and the TTL adapter:
Another option could be that the TTL trigger receiver is powered by 5V from an USB and TTL trigger is sent by an external device by the BNC connector. To integrate this it could be created a connection like in the following image:
Every time a pulse is sent, it can be seen in NIC software as in the following image:
To try the TTL adapter before using it in a real subject we can do the following connections using the Tesboard. In the following example we will receive the pulse in channel P7:
