# uBlox Sara-U270 comm interface timing out

**URL:** <https://forums.freertos.org/t/ublox-sara-u270-comm-interface-timing-out/14582>\
**Category:** ST\
**Tags:** debug\
**Created:** [March 1, 2022, 8:54pm UTC](https://forums.freertos.org/t/ublox-sara-u270-comm-interface-timing-out/14582 "2022-03-01T20:54:56Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![afymagic](https://avatars.discourse-cdn.com/v4/letter/a/e8c25b/32.png) [@afymagic](https://forums.freertos.org/u/afymagic)\
**Post date:** [March 1, 2022, 8:54pm UTC](https://forums.freertos.org/t/ublox-sara-u270-comm-interface-timing-out/14582/1 "2022-03-01T20:54:56Z")

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I’m trying to integrate a stm32F205 with a Sara U-blocks U270 using the Sara R4 port provided with the cellular interface. I am able to send at commands and receive the response within the iot fifo buffer but the iot interface continues to return busy even after the end of the message has completed and eventually times out.

 ![image](https://d2v6vdsk2p900z.cloudfront.net/original/2X/3/3d80815e580f162704102f79ca36183aac7be98d.png)

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**Author:** ![Fresh](https://avatars.discourse-cdn.com/v4/letter/f/2acd7d/32.png) [@Fresh](https://forums.freertos.org/u/Fresh)\
**Post date:** [March 8, 2022, 1:53am UTC](https://forums.freertos.org/t/ublox-sara-u270-comm-interface-timing-out/14582/2 "2022-03-08T01:53:32Z")

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Hi Adam,

The question is duplicated in this thread.

> [@FreeRtos on nrf52 with BG95M2](https://forums.freertos.org/t/freertos-on-nrf52-with-bg95m2/11886/5):
>
> Hi Ukhan717, The AT commands of BG95 and BG96 are very similar. We have tested on the BG95 EVB board with firmware version BG95M1LAR02A02\_01.002.01.002. After applying the patch below, the windows simulator demo project of BG96 can run with this BG95 EVB in our environment. We suggest updating the BG95 firmware to the latest. In the past we did see more incompatibility between BG96 and BG95. But after updating firmware the difference narrowed, and we were able to make it work by just apply…

It could be the comm interface problem.  
Detail reasons and patches are provided in previous thread.

We can do the followings to help locating the problem:

1. Use FreeRTOS windows simulator as a comparison.
2. Add more debug log to indicate the timeout reason.

A patch to reproduce this problem on windows simulator is also provided to help understanding this problem.

Let’s move the discussion in previous thread.  
Please provide more information for discussion.