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KEA Interrupt Input Killing ADT7420 Sensor

Question asked by Kas Lewis on Dec 30, 2014
Latest reply on Nov 25, 2015 by vignesh balaji

Hello ,


I am using an ADT7420 (from Analog Devices) with an interrupt set to 35 Celsius. The issue I am having is the when the interrupt fires (whether active low or active high) the sensor stops working.  By stop working I mean the I2C communication stops and can not be reconnected without resetting the whole system. The interrupt pin is directly connected to PA0 which is configured as a KBI. I have measured the input pin on the micro I am using (KEA64 by Freescale) and it is sitting at 0.60 V. When the ADT7420 is disconnected from this pin there is no issue. I was therefore wondering why this may be occurring and how I may go about mitigating the issue.

 

Would a simple diode help or would putting an inverter inline to isolate the ADT7420 from the KEA64 solve the issue. Any information on why this occurs or away to prevent it from happening would be much appreciated.

 

Thanks

 

2014-12-30 03_34_00-Edit Message KEA Interrupt Input Killing ADT7420 Sensor _ Freescale Community.jpg

Interrupt firing and I2C stopping abruptly.

 

2014-12-30 03_34_51-Edit Message KEA Interrupt Input Killing ADT7420 Sensor _ Freescale Community.jpg

Close up of interrupt firing and I2C stopping with no stop bit


//Interrupt Handlers
void KBI0_IRQHandler()
{
    if((GPIOA_PDIR & GPIO_PDIR_PDI(0x1)))                    //Temperature interrupt 
    {
        //Deal with high temperature scenario
        GPIOA_PTOR |= 0x10000;                                          //Set output low, toggle LED0


    }   
    read_Temperature();//TODO: Should disable interrupts here read in mainand then renable interrupts
    KBI0_SC |= KBI_SC_KBACK_MASK;                                       //Clear interrupt flag
}



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