# GPIO Voltage output

**URL:** <https://forum.sierrawireless.com/t/gpio-voltage-output/1945>\
**Category:** Legacy FX/FXT series\
**Created:** [February 27, 2008, 6:56pm UTC](https://forum.sierrawireless.com/t/gpio-voltage-output/1945 "2008-02-27T18:56:31Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ceibanez](https://avatars.discourse-cdn.com/v4/letter/c/e5b9ba/32.png) [@ceibanez](https://forum.sierrawireless.com/u/ceibanez)\
**Post date:** [February 27, 2008, 6:56pm UTC](https://forum.sierrawireless.com/t/gpio-voltage-output/1945/1 "2008-02-27T18:56:31Z")

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I’m making a test box to interact with the developer kit, and the fastract supreme. I think I remember reading somewhere that the input GPIO for digital input was about 2.8v. I want it to confirm this and I was wondering if you knew the tolerance values to get a logical on/off. (x+2.8v, 2.8v-x)  
Thanks