Millisecond accurate USB TTL event marking module technical specifications
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For the more technically minded, specifications for our USB TTL Module can be seen below. We think it's important for you to have full confidence in our millisecond accurate USB TTL Module when using it in your psychology experiments for event marking/triggering*

We have taken the decision to publish full technical and timing specifications for our USB TTL Module as all too often the equipment you use on a daily basis is of unknown quality.

In our view, if other vendors do not publish specifications for their hardware or software you should not be using it!

 


Key features TTL breakout board Pinouts Technical specifications Pricing Config software  
Technical specifications

Physical specifications *Nominal accuracy
  • ABS plastic enclosure – Dimensions: 67.1mm x 28.2mm x 67.1mm (WHD)
  • Full-speed USB 2.0 (compatible with USB 3.0)
  • 1x 25-way male D connector for connecting your equipment to 8x TTL Output lines and 8x TTL Input lines from your equipment. Plus 8x GND pins
  • Appears to the host PC/Mac/Linux system as a standard serial port (VCP – Virtual Com Port)
  • Connects to the host PC via standard USB type A to B lead
  • Fully updatable firmware - 32K flash RAM (100,000 Erase/Write Cycles)
  • Checks for a TTL event mark or trigger event 109,000 times a second (109kHz sampling rate)
  • Typical time to send a TTL output or event mark from a two byte hex code from the PC, 254µs#
  • Typical time to respond to a TTL input/trigger pulse or sync signal and send a two byte hex code to the PC, 350µs#
  • Typical time for 50 TTL outputs or event marking pairs (on|off), M = 290µs, SD = 10µs, measured using our configuration and latency validation software for Microsoft Windows (Win 7 64 SP1, USB 2) and modules internal hardware timer#
  • Supplied with configuration and latency validation software for Windows XP, Vista, Win 7, Win 8/8.1 and Win 10
  • Built-in hardware timing checks based on elapsed time between two sequential event marks

#Dependent on specific USB subsystem and using the USB TTL Configuration utility to check correct for correct installation.

*Remember although our USB TTL event marking modules are millisecond accurate they can't automatically correct for any mistimings that are inherent within the experiment generator you use (key features).


In order to validate our claims for accuracy we have tested the shipping electronics and firmware thoroughly. Below are a series of screen grabs from one of our Tektronix oscilloscopes.

   
Typical time to send a TTL output or event mark (orange) from a two byte hex code from the PC (blue) TTL sampling rate, i.e. how many times a second TTL I/O status is checked
   
   
Typical time for 50 TTL outputs or event marking pairs (on|off) measured using our configuration and latency validation software for Microsoft Windows (Win 7 64 SP1, USB 2) Typical time to respond to a TTL input/trigger pulse or sync signal (orange)
and send a two byte hex code to the PC (blue)