# Hardware Triggering The Extender’s hardware triggering feature allows you to mark external events for post-processing. The input trigger pulses are injected into to the headset data stream within +/-1 sample. There is a fixed 60ms delay between the trigger and the channel signal data which is due to the filter delay for the channels.The trigger pulse is shown in EmotiVPRO as a pink line and is also saved in the hardware column when exporting a file. ![EmotivPRO Trigger Pulses](https://lh3.googleusercontent.com/eCigpkNQny4wYK9QpohujPl_BiYyXg4AWVk8UhuZ-PiWYzPvksNkwfcHY2UaDzduOpsgR0S8WvOXM99-e-UgsvhOoef5ZSvdVDkLADFi3ROqADjQUEp5fc455bF6T3WzqlWNNwcW) EMOTIV has provided a custom 1m trigger cable with every extender. The cable has two tinned wires red and black that can be connected to an external trigger source. The input polarity of the trigger is reversable and utilises an opto-coupled photo transistor Vishay VOL628A (see [datasheet](https://www.vishay.com/docs/82401/vol628a.pdf)). This component requires a minimum of 1mA forward current and maximum of 60mA. The input design has has an internal limiting resistor of 1kOhm. The trigger input voltage need to be between 2.5 -15V and can be driven directly from an arduino or a parallel port. Please see below Arduino examples: --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://emotiv.gitbook.io/extender-manual/hardware_triggering.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.