# TTL trigger pulse fMRI

**URL:** <https://psychtoolbox.discourse.group/t/ttl-trigger-pulse-fmri/4872>\
**Category:** Programming Help\
**Tags:** experiment-design\
**Created:** [March 1, 2023, 5:44pm UTC](https://psychtoolbox.discourse.group/t/ttl-trigger-pulse-fmri/4872 "2023-03-01T17:44:45Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Ram88](https://avatars.discourse-cdn.com/v4/letter/r/6de8d8/32.png) [@Ram88](https://psychtoolbox.discourse.group/u/Ram88)\
**Post date:** [March 1, 2023, 5:44pm UTC](https://psychtoolbox.discourse.group/t/ttl-trigger-pulse-fmri/4872/1 "2023-03-01T17:44:45Z")

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Hi experts,

I use a Matlab code for a visual task on an fMRI study. We have a VPixx system for delivering audio/video and recording triggers and responses. The trigger pulse is coming from TTL 15. As this is not translating into a keyboard press, I am wondering whether we can use ResponsePixx on Matlab to get the starting trigger pulse. Could you please advise?

Thanks,  
Ram

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**Author:** ![dmichaud](https://avatars.discourse-cdn.com/v4/letter/d/ac91a4/32.png) [@dmichaud](https://psychtoolbox.discourse.group/u/dmichaud)\
**Post date:** [March 1, 2023, 7:03pm UTC](https://psychtoolbox.discourse.group/t/ttl-trigger-pulse-fmri/4872/2 "2023-03-01T19:03:40Z")

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Hello Ram,

VPixx has a couple of VOCAL (VPixx Online Classroom and Library) guides to get you started on using TTL triggers in your code.

You can take a look at [https://vpixx.com/vocal/rt\_responsepixx/](https://vpixx.com/vocal/rt_responsepixx/) and [https://vpixx.com/vocal/introduction-to-registers-and-schedules/](https://vpixx.com/vocal/introduction-to-registers-and-schedules/)

Both of these guides will describe how to use digital inputs and how to read their values and monitor them.

However, we do not have any code that converts button presses to a keyboard press.

Do not hesitate to contact us directly for any further question.

Danny M  
VPixx Technologies