Why is the LPC804 going into IntDefaultHandler()?

[drsmith_yorku]

I'm trying to port ISR code for a pushbutton on the LPC804 (OM40001) from C to C++14.  It works fine in C.  Unfortunately, in C++, my ISR isn't engaging when I push the pushbutton on the board.  Instead, the chip hangs in the while loop found in the IntDefaultHandler() generated by the SDK.

On the LPC804 board I'm using the User pushbutton on the main board and one of the LEDs on the add-on capacitive touch board.

I'm not sure why this is happening and am looking for some advice as to how to figure it out.

James

#include "LPC804.h"

#define LED_USER2 (20) // One of the LED on the capacitive touch board.  (PIO0_20)

#define BUTTON_USER1 (13) // GPIO 13 (PIO0_13) is connected to the button.

int main(void) {

    // disable interrupts

    __disable_irq();     // turn off globally

    NVIC_DisableIRQ(PIN_INT0_IRQn); // turn off the PIN INT0 interrupt.

    // ----------------------- Begin GPIO setup ------------------------------------

// Set up a general GPIO for use within the Interrupt Service Routine for MRT

    // Only the ISR needs the GPIO.  (PB8 & PB9)

SYSCON->SYSAHBCLKCTRL0 |= ( SYSCON_SYSAHBCLKCTRL0_GPIO0_MASK | // GPIO is on

SYSCON_SYSAHBCLKCTRL0_GPIO_INT_MASK); // GPIO Interrupt is on

// Put 0 in the GPIO and GPIO Interrupt reset bit to reset it.

// Then put a 1 in the GPIO and GPIO Interrupt reset bit to allow both to operate.

// manual: Section 6.6.10

SYSCON->PRESETCTRL0 &= ~(SYSCON_PRESETCTRL0_GPIO0_RST_N_MASK |

SYSCON_PRESETCTRL0_GPIOINT_RST_N_MASK); // reset GPIO and GPIO Interrupt (bit=0)

SYSCON->PRESETCTRL0 |= (SYSCON_PRESETCTRL0_GPIO0_RST_N_MASK |

SYSCON_PRESETCTRL0_GPIOINT_RST_N_MASK); // clear reset (bit=1)

// Config the Pushbutton  for input and LED  for output

// Remember: only bits set to 1 have an effect on DIRCLR and DIRSET registers.

//     bits cleared to 0 are ignored.

// Therefore, use DIRCLR to select input and DIRSET to select output

GPIO->DIRCLR[0] = (1UL<<BUTTON_USER1); // input on (BUTTON_USER1)

GPIO->CLR[0] = (1UL<<LED_USER2); // LED is on(     turn off   )

GPIO->DIRSET[0] = (1UL<<LED_USER2); // output on  (LED_USER2)

// ----------------------- end of GPIO setup -----------------------------------

// Set up GPIO IRQ: interrupt channel 0 (PINTSEL0) to GPIO 

SYSCON->PINTSEL[0] = BUTTON_USER1; // PINTSEL0 is BUTTON_USER1

// Configure the Pin interrupt mode register (a.k.a ISEL) for edge-sensitive

// on PINTSEL0.  0 is edge sensitive. 1 is level sensitive.

PINT->ISEL = 0x00; // channel 0 bit is 0: is edge sensitive (so are the other channels)

// Use IENR or IENF (or S/CIENF or S/CIENR) to set edge type

// Configure Chan 0 for only falling edge detection (no rising edge detection)

PINT->CIENR = 0b00000001; // bit 0 is 1: disable channel 0 IRQ for rising edge

PINT->SIENF = 0b00000001; // bit 0 is 1: enable channel 0 IRQ for falling edge

// Remove any pending or left-over interrupt flags

PINT->IST = 0xFF; // each bit set to 1 removes any pending flag.

// enable global interrupts & GPIO INT channel 0

NVIC_EnableIRQ(PIN_INT0_IRQn); // GPIO interrupt

__enable_irq();  // global

    /* Enter an infinite loop, check the pushbutton on GPIO8.*/

    while(1)

    {

        asm("NOP");

    }

    return 0 ;

}

// ---------------------------------------

// ISR for the GPIO Interrupt

//

// A GPIO interrupt has been detected.  Enable the MRT oneshot interrupt

// so that you can check on the GPIO state in a specific amount of time.

// after it has settled out (debounced).

//

// Could check GPIO directly with

//  if(GPIO->B[0][8] & 1)  // Is GPIO0_8 a 1? GPIO0_8 is the pushbutton

//

// ---------------------------------------

void PIN_INT0_IRQHandler(void)

{

// was an IRQ requested for Channel 0 of GPIO INT?

if (PINT->IST & (1<<0))

{

// remove the any IRQ flag for Channel 0 of GPIO INT

PINT->IST = (1<<0);

// TOggle the LED

GPIO->NOT[0] = (1UL<<LED_USER2); // 

}

else

{

  asm("NOP");  // Place a breakpt here if debugging.

}

return;

}

[converse · Accepted solution]

See this FAQ

https://community.nxp.com/thread/389035 

[drsmith_yorku]

yup! it works!

// ---------------------------------------

// ISR for the GPIO Interrupt

//

// A GPIO interrupt has been detected.  Enable the MRT oneshot interrupt

// so that you can check on the GPIO state in a specific amount of time.

// after it has settled out (debounced).

//

// Could check GPIO directly with

//  if(GPIO->B[0][8] & 1)  // Is GPIO0_8 a 1? GPIO0_8 is the pushbutton

//

// for C++ https://en.wikipedia.org/wiki/Compatibility_of_C_and_C%2B%2B#Linking_C_and_C.2B.2B_code

// ---------------------------------------

extern "C" {

void PIN_INT0_IRQHandler(void)

{

// was an IRQ requested for Channel 0 of GPIO INT?

if (PINT->IST & (1<<0))

{

// remove the any IRQ flag for Channel 0 of GPIO INT

PINT->IST = (1<<0);

// TOggle the LED

GPIO->NOT[0] = (1UL<<LED_USER2); //

}

else

{

  asm("NOP");  // Place a breakpt here if debugging.

}

return;

}

}

[drsmith_yorku]

thanks!  Will try it out.