# Host Firmware Update UART pins?

**URL:** <https://discuss.blues.com/t/host-firmware-update-uart-pins/2869>\
**Category:** Hardware\
**Created:** [February 22, 2025, 11:46pm UTC](https://discuss.blues.com/t/host-firmware-update-uart-pins/2869 "2025-02-22T23:46:46Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mtrobregado](https://avatars.discourse-cdn.com/v4/letter/m/4da419/32.png) [@mtrobregado](https://discuss.blues.com/u/mtrobregado)\
**Post date:** [February 22, 2025, 11:46pm UTC](https://discuss.blues.com/t/host-firmware-update-uart-pins/2869/1 "2025-02-22T23:46:46Z")

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Hi,

I plan to update the firmware of ESP32 from Notehub. I am going to use Notecard Cell + WiFi and Notecarrier A. I read about host firmware update and watched your youtube video. Why do I need a separate UART communication for host firmware update using AUXRX and AUXTX?

 ![image](https://us1.discourse-cdn.com/flex020/uploads/blues/original/2X/f/f09702c55510f5cf48439703271e360fa13f1461.jpeg)

For sending notes from ESP32 the connection is below.  
ESP32 RX1 ← Notecarrier A TX  
ESP32 TX1 → Notecarrier A RX

For host firmware update from ESP32  
ESP32 RX2 ← Notecarrier A AUXTX  
ESP32 TX2 → Notecarrier A AUXRX.

Can I just use 1 UART communication?

Regards,  
Markel

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<div class="post-metadata">

**Author:** ![mtrobregado](https://avatars.discourse-cdn.com/v4/letter/m/4da419/32.png) [@mtrobregado](https://discuss.blues.com/u/mtrobregado)\
**Post date:** [February 25, 2025, 9:48pm UTC](https://discuss.blues.com/t/host-firmware-update-uart-pins/2869/2 "2025-02-25T21:48:34Z")

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> [@mtrobregado](#):
>
> For host firmware update from ESP32  
> ESP32 RX2 ← Notecarrier A AUXTX  
> ESP32 TX2 → Notecarrier A AUXRX.

Just want to correct myself

For host firmware update from Notecard and Notecarrier.  
ESP32 RX2 ← Notecarrier A AUXTX  
ESP32 TX2 → Notecarrier A AUXRX.

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**Author:** ![abucknall](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/abucknall/32/1335_2.png) [@abucknall](https://discuss.blues.com/u/abucknall)\
**Post date:** [February 26, 2025, 4:19pm UTC](https://discuss.blues.com/t/host-firmware-update-uart-pins/2869/3 "2025-02-26T16:19:56Z")

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Hi @mtrobregado,

I had to check this one with the team, but there’s no reason why this wouldn’t work for Host firmware updates; connecting to a single UART should be fine. The one piece of advice to share with you is that you may find that you’re drawing additional current if you have AUX-EN pulled high frequently.

Thanks,  
Alex