# Stuck in NAIrqHandler()

**URL:** <https://forums.digi.com/t/stuck-in-nairqhandler/6064>\
**Category:** NET+OS\
**Created:** [June 9, 2008, 1:44pm UTC](https://forums.digi.com/t/stuck-in-nairqhandler/6064 "2008-06-09T13:44:42Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![quentin](https://avatars.discourse-cdn.com/v4/letter/q/e47c2d/32.png) [@quentin](https://forums.digi.com/u/quentin)\
**Post date:** [June 9, 2008, 1:44pm UTC](https://forums.digi.com/t/stuck-in-nairqhandler/6064/1 "2008-06-09T13:44:42Z")

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Hi,

I have a problem with my NET+OS 7.3 project (my first one) on ConnectME:

My code never get out of an NAIrqHandler(), and I don’t know the reason. My app do the following :

- Configure serial port B as dialog port instead of port A, which I use to communicate with another uC.
- Start another thread (I don’t know if I can use the root thread for all my stuff, but as every example seem to use thread, so did I) who will use serial to poll data from the other uC and toggle some GPIO pin through NAsetGPIOpin().

As I didn’t configure anything particuliar for the interrupt, I don’t undestant which interrupt cause the problem. Can the GPIO things or serial communication be the cause?

Any help realy welcomed !  
And if need more information is need, just tell it 🙂

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**Author:** ![quentin](https://avatars.discourse-cdn.com/v4/letter/q/e47c2d/32.png) [@quentin](https://forums.digi.com/u/quentin)\
**Post date:** [June 9, 2008, 3:52pm UTC](https://forums.digi.com/t/stuck-in-nairqhandler/6064/2 "2008-06-09T15:52:56Z")

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update :

After some research, I found that my problem come from the DCD line of the UART.  
I use the UART in two wire mode (only tx-rx) by defining BSP\_GPIO\_MUX\_SERIAL\_A to BSP\_GPIO\_MUX\_SERIAL\_2\_WIRE\_UART in gpio.h.  
I use the GPIO0 (DCD) for controling a reset line by defining BSP\_GPIO\_INITIAL\_STATE\_PIN\_A0 to BSP\_GPIO\_INITIAL\_STATE\_OUTPUT\_DRIVER\_LOGIC1. But it seem that the pull up on this line make the UART interrupt because of a break condition. Does anyone know how to desactivate this behaviour ?

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**Author:** ![cchaball](https://avatars.discourse-cdn.com/v4/letter/c/ee59a6/32.png) [@cchaball](https://forums.digi.com/u/cchaball)\
**Post date:** [July 4, 2008, 4:17pm UTC](https://forums.digi.com/t/stuck-in-nairqhandler/6064/3 "2008-07-04T16:17:28Z")

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I got a problem looking very similar (output GPIO not working as it would be).  
I resolved it setting explicitly the GPIO level with NasetGPIOpin(). I got doubt on the fact that the INITIAL\_OUTPUT\_STATE is taken in account.

let to know if it helps.

Colin