# P1 UART 5V Tolerant?

**URL:** <https://community.particle.io/t/p1-uart-5v-tolerant/32059>\
**Category:** Hardware\
**Created:** [April 24, 2017, 10:05am UTC](https://community.particle.io/t/p1-uart-5v-tolerant/32059 "2017-04-24T10:05:47Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![simmikolon](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/simmikolon/32/12121_2.png) [@simmikolon](https://community.particle.io/u/simmikolon)\
**Post date:** [April 24, 2017, 10:05am UTC](https://community.particle.io/t/p1-uart-5v-tolerant/32059/1 "2017-04-24T10:05:47Z")

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I am using the P1 module to read and send data from a 5V MCU - In the datasheet of the P1 some PINs are marked as “5V Tolerant” - However currently I’ve planned to use a level converter here but when this isn’t needed I would leave it out. But this would also require that the P1 does provide 5V signals!? Is this the case? Or is it better to have level converter between UART of P1 and MCU?

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**Author:** ![ScruffR](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/scruffr/32/6952_2.png) [@ScruffR](https://community.particle.io/u/ScruffR)\
**Post date:** [April 24, 2017, 12:13pm UTC](https://community.particle.io/t/p1-uart-5v-tolerant/32059/2 "2017-04-24T12:13:46Z")

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The info which pins are 5V tolerant can be found here  
[https://docs.particle.io/datasheets/p1-datasheet/#peripherals-and-gpio](https://docs.particle.io/datasheets/p1-datasheet/#peripherals-and-gpio)

And whether your “client” can deal with 3.3V HIGH on RX to recognise the bit correctly depends on that device and is beyond us to know.  
The respective datasheet should give you some info about the level thresholds. In general I’d think it should be OK.

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**Author:** ![simmikolon](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/simmikolon/32/12121_2.png) [@simmikolon](https://community.particle.io/u/simmikolon)\
**Post date:** [April 27, 2017, 8:37am UTC](https://community.particle.io/t/p1-uart-5v-tolerant/32059/3 "2017-04-27T08:37:23Z")

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Thanks for this information. Unfortunately the MCU does not deal with 3,3V HIGH - so there is level-shifting needed. I just thought that if the Photon can deal with 5V UART I somehow thought that it sends out 5V on TX. But it doesn’t, right!?

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**Author:** ![ScruffR](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/scruffr/32/6952_2.png) [@ScruffR](https://community.particle.io/u/ScruffR)\
**Post date:** [April 27, 2017, 8:46am UTC](https://community.particle.io/t/p1-uart-5v-tolerant/32059/4 "2017-04-27T08:46:10Z")

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Nope 5V tolerant does _only_ mean 5V can be tolerated at that pin but it does not mean it’ll ever output 5V.