# sending TTL trigger via USB

**URL:** <https://psychtoolbox.discourse.group/t/sending-ttl-trigger-via-usb/1000>\
**Category:** Uncategorized\
**Created:** [April 19, 2014, 5:30am UTC](https://psychtoolbox.discourse.group/t/sending-ttl-trigger-via-usb/1000 "2014-04-19T05:30:57Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![vinu\_vinni11](https://avatars.discourse-cdn.com/v4/letter/v/cdc98d/32.png) [@vinu\_vinni11](https://psychtoolbox.discourse.group/u/vinu_vinni11)\
**Post date:** [April 19, 2014, 5:30am UTC](https://psychtoolbox.discourse.group/t/sending-ttl-trigger-via-usb/1000/1 "2014-04-19T05:30:57Z")

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I am new to Psychtoolbox. &nbsp;i designed a script for a test, in that script randomly arrows appear on screen. i want that, after seeing arrows subject should press a key, and on pressing key a TTL trigger should be send to a external device via USB.  
Could some one help me to send TTL trigger vis USB to device. I am not asking for the code, but asking for some guidance or tutorial, coz I am totally unaware about TTL triggering.&nbsp;