Chronos Adapter for TMSi SAGA 32/64+ [42936]

This article applies to:

E-Prime 3.0

Chronos

Detail

Experiment Author: Psychology Software Tools, Inc.

The Chronos Adapter for TMSi SAGA 32/64+ sample experiment illustrates how to use Task Events to send markers from the E-Prime experiment to the TMSi SAGA 32/64+ EEG System. 

Abstract

The sample experiment presents a Visual Oddball Task: each trial presents the letter "O" or "X" and the participant's task is to distinguish between these letters. 80% of the trials present the letter "O" and 20% of the trials present the letter "X". The experiment sends the marker value 65534 (which is received as a 1 in the TMSi software) when the letter "O" is shown and the value 32767 (which is received as the value 32768 in the TMSi software) when the letter "X" is shown.

NOTE: The TMSi SAGA 32/64+ EEG System uses Active Low Logic (Negative Logic). To set a digital input active using Active Low Logic, send 0V on the desired bit; to set a digital input inactive (clear a bit), send 5V on the desired bit. Since the TMSi SAGA supports 16 digital inputs, the largest integer value that can be sent is 65535; therefore, to determine what marker value is received by TMSi SAGA subtract the integer value that is sent from E-Prime from 65535. For example, if the marker value sent from E-Prime is integer 8, then TMSi SAGA receives the integer value 65527. To set all of the digital inputs inactive, send the integer value 65535; to set all of the digital inputs active, send the integer value 0.

Note that newer software packages included with SAGA systems provide users with the option to invert the logic levels. If this option is used then the E-Prime experiment can specify marker values assuming Active High instead of Active Low Logic. This sample assumes Active Low Logic. If you have the option to invert the logic levels and prefer to program the experiment using Active High Logic instead, see Chronos Adapter for BioSemi [42885]; this article provides an example of using Active High Logic with an adapter that uses the same 16 bit-to-pin mappings as the Chronos Adapter for TMSi SAGA 32/64+.

The Chronos Adapter for TMSi SAGA 32/64+ provides access to 16 digital outputs (from Chronos to the SAGA 32 or 64+ amp) as shown below:

The sample experiment illustrates the digital output functionality. When Chronos sends a marker on its first digital output, the TMSi SAGA 32/64+ EEG System receives the value on Trigger_In0 (pin 1). When Chronos sends a marker on its sixteenth digital output, the system receives it on Trigger_In15 (pin 16).  To determine which TMSi SAGA 32/64+ Digital Input receives the Chronos output, do the following:

1. Represent the integer marker being sent as a binary number (see INFO: Choosing a marker value to send from E-Prime to an external device [42529] for more information on integer and binary numbers).
2. Map the binary number to Chronos's digital outputs to determine which outputs are set active (set to 0V).
3. Examine which TMSi SAGA 32/64+ Digital Inputs map to the Chronos Digital Outputs that are set active.

For example, the sample sends the integer value 65534 (1 in the TMSi software) when the stimulus = the letter "O":

1. Integer value 65534 (1 in the TMSi software) equals the binary number 1111 1111 1111 1110 (Least Significant Bit is right-most bit).
2. 1111 1111 1111 1110 sets the first Chronos digital output active; all other digital outputs are inactive.
3. As shown in the table above, the first Chronos Digital Output maps to TMSi SAGA 32/64+ Trigger_In0.

The sample sends the integer value 32767 (32768 in the TMSi software) when the stimulus = the letter "X":

1. Integer value 32767 (32768 in the TMSi software) equals the binary number 0111 1111 1111 1111.
2. 0111 1111 1111 1111 sets the sixteenth Chronos digital output active; all other digital outputs are inactive.
3. The sixteenth Chronos Digital Output maps to TMSi SAGA 32/64+ Trigger_In15.

NOTE: The experiment changes the values for the Chronos Digital Outputs at the start and end of the experiment: the default value of 0 is changed to 1. This sets all of the outputs to logical high at the start of the experiment and resets them to logical high at the end of the experiment. See the Digital Out tab of the Chronos Device for details.

NOTE: Extract all the files in the attached .zip file to the same folder. The sample experiment displays images that must be located in the same folder as the experiment.