# New unit fails UART Loopback test

Source: https://forum.modalai.com/topic/2444/new-unit-fails-uart-loopback-test
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2023-07-19 02:38:50 UTC by Evan Hertafeld 0
Replies: 0 · Views: 278

## Evan Hertafeld 0 · 2023-07-19 02:38:50 UTC

Hi all,

We recently purchased a Voxl Deck (not our first) and our application (which has been running great on other units) wasn't working - specifically we weren't getting anything on the UART line. Sure enough, we ran the included loopback test on UART 12 and it failed - the other ports passed.

Needing only 2 uarts, we moved our application to the other two UART ports... But we find that if one is in use, the other drops out. I assume this is a hardware issue with our unit. Furthermore, we ideally need all three available UART ports for our application so one and a half is a non-starter.

As part of our setup we flash the system image and the issue persists after a re-flash. An identical software setup has worked just fine on multiple other Voxl Decks.

Assuming this to be a hardware defect, we requested a return in private support channel but were instructed to post here instead. Can someone either facilitate a return/replacement or provide other guidance?