NMI handler

[andreiszeghy]

Hello,

  I'm using an LPC1769 MCU and have pin P2[10] configured as an external interrupt.  I knew this pin was also the Non-Maskable Interrupt, but at the time I was sure that this pin would never be asserted during reset.  Well, of course, come to find out that on rare occasions this pin is triggered, and stays triggered,  when the MCU resets. So the code winds up locked in the NMI handler.

  I am not using the NIM otherwise and the handler currently looks like this:

void NMI_Handler(void)
{
    while(1) {}
}

  Is there anything I can do in the handler to manage the occasions when the MCU reset's with the NMI asserted?

Thanks, any info is greatly appreciated,

Andrei

[andreiszeghy]

Hi Jeremy,

   Thanks for the reply.  There already is a pull-up resistor in the circuit, the input being "triggered" is not a bug.  On occasion there is physically something in front of a sensor that I never anticipated being there. 

  My mistake, you are correct, I overlooked the ISP mode detail on that pin!  A lot of bad words are firing off in my head!  I don't think there is any way to get out of this scenario.  I'll have to make some non programmatic changes to work around this.

Thank you,

Andrei

[jeremyzhou · Accepted solution]

Hi Andrei Szeghy，

Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.
According to your description, it seems MCU won't boot up successfully on rare occasion because of P2[10] is 'triggered', is it right?
However, I don't agree with the reason you pointed out, I think the MCU enter into the ISP mode, to validate this assumption, please adding a pull-up resistor (10 KΩ) on the P2[10] pin to terminate this 'issue'。

Have a great day,
TIC

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