UPF
Usb to Parallel FIFO
A convenient and accurate parallel Input/Output USB device for E-Prime 2 Pro, and E-Prime 3.
Device Description
The device include 8 logical TTL input/output ports (0 to +5V). Each port has a temporal resolution of 50 ns and the complete output voltage transition from GND to 5V takes approximately 400 µs. The device is controlled via microprocessor at 12 MHz. A Windows compatible .dll enable communication with the device.
E-Prime Integration
E-prime (v.2 Pro and v.3) integration was reached via a custom made Package, built with E-Prime Professional.
After loading our custom Package in E-Prime, one can send or receive a TTL pulse over a given port as typically done to command a PP pin read or write.
Our UPF device in integration with E-prime guarantee the millisecond accuracy required by Psychological and Neurophysiological experiments. We run extensive side by side comparisons between the parallel port and our UPF, please find it here.
Direct USB
Direct USB is a software that let's you flexibly and easily create personalized I/O "tasks". First you decide how many Input and Output channels to use, then you can set their behavior. For example you can generate output TTLs, with any delay, if some Input combination meet certain criteria.
Therefore you can use Direct USB to acquire external triggers, multiple response buttons and conditionally generate output pulses to control or synchronize external equipments.
TTLs can be sent also via the keyboard. Any four keyboard button can be associate to any output channel. If one of these buttons is pressed, 5V will be delivered through the associated output channel.
Direct USB is compatible with any Windows version starting from Win2000 and works only with our UPF device. (read more...)
More
Most psychological and neurophysiological experiments require the accurate control of stimuli generation, response recording as well as external devices synchronization. Such operations are typically performed via custom made or public software. For instance, the experimenter may want to measure different aspects of human behavior (i.e. button press, force sensors, optical or touch sensors, accelerometers, etc.) in association with other neurophysiological indices measured with external equipments (i.e. electroencephalography, functional magnetic resonance imaging, transcranial magnetic stimulation, etc.). These kind of experiments are based on the general assumption that one have to correlate brain states to measurable behavioral variables (Gazzaniga, Ivry, Mangun, 2002). Therefore, computer controlled experiments require particular accuracy and consistency when dealing with timing and synchrony among separate machines.
In recent years, several commercial or open source software have been proposed for the Experimental Control and Management (ECM) such as E-Prime, Presentation, PsyScope, or the PsychToolbox for MatLab, among others. In fact, we know that new generation operating systems are not optimized for timing accuracy (MacInnes, Taylor, 2001; Chambers, Brown, 2003; Plant, Hammond, Turner, 2004) and the advantage of using ECM software is that they are designed for this specific purpose, often incorporating low level routines and setting highest priority to them. In fact, these software guarantee millisecond accuracy in these operations and are productively used in thousands of labs around the world.
Synchronous recordings are typically achieved by relaying on a master computer controlling the experimental work-flow and by sending triggers to other computers (or external equipments). These triggers are then used by slave systems for synchronization, start acquisitions or even the generation of further commands. These basic I/O tasks are generally handled via the Parallel Port (PP). In fact, this port has proven to be a reliable and easy to use solution in psychological and neurophysiological settings (Voss, Leonhart, Stahl, 2007; Stewart, 2006).
Nevertheless, the PP is an end of life technology. The PP was originally developed to control printers and nowadays is being replaced by other ports such as the USB. Most recent motherboards do not include the PP and one must resort to PCI or PCI express external boards. However, different boards from different manufacturer may have different timing performance (http://www.pstnet.com/eprimeport.cfm) and one must pay particular attention when building a new experimental setup. Moreover, average laptops do not include a PP since few years. Until some time ago, laptops were not a suitable experimental platform due to inherent lack of performance. Newer generations of portable computers instead, offer quite enough power to run most kind of experiments, and in some cases they might even be the platform of choice. As a matter of facts, experiments run outside usual lab settings (such as hospitals, schools, subject's home, etc.) may indeed require a portable setup.
Therefore, the only solution for those people requiring a portable experimental setup is either the use of PCMCIA adapters or move to the USB technology. PCMCIA - PP adapters, however, proved extremely unreliable in the time domain (http://www.pstnet.com/eprimeport.cfm) and therefore may not be a viable alternative. On the other hand, USB protocols unlike the PP, are based on periodic polling. The host computer periodically queries input devices for state changes. Detection of any event is quantized in time and interval is typically fixed at 8 msec. Moreover, additional uncertain delays could arise due to the variability in the latency between event detection and the handling of the event by the operating system, as well as event registration by the user program. Therefore, also an USB-based solution does not guarantee the necessary millisecond accuracy.
Here, in order to solve this issue, we present a new commercial USB device including an internal clock and microprocessor that keeps control of event timing with sub-milliseconds accuracy that may be used as a virtual PP. The device has indeed I/O capability and we offer a set of tools enabling complete integration in the E-Prime environment. We tested our USB device along side the PP in several timing tests on a last generation desktop computer to verify reliability of our product against the gold-standard in the field (PP). We also run a typical EEG Event-Related Potentials (ERPs) e-prime script on both a desktop and a laptop, to test the reliability of our product in normal lab usage. Timing in all tests were verified via an external A/D board with an independent high-precision clock.
UPF use examples link...
Contact
Price and Order
Rosario Canto
University of Ferrara
D.S.B.C.S. Section of Human Physiology
Via Fossato di Mortara 17/19
44121 Ferrara
Tel: 0532 455932
Fax: 0532 455242
e-mail: rosario.canto@unife.it |
Alessandro D'Ausilio
IIT, The Italian Institute of Technology
CTNSC@UniFe - Center of Translational Neurophysiology
Via Fossato di Mortara, 17/19
44121- Ferrara
alessandro.dausilio@iit.it |
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