Starterware/EK-TM4C1294XL: Button(SW1) Interrupts on TIVAC- 1294xl launchpad

Nishit said:

Now in main.c i have the following code. 

void buttonpress(void)

Most importantly - have you placed & declared your, "buttonpress()" function w/in your, "Start-Up file" - and mated it to "Port J's ISR slot?"     Note that there is a "long list" of ISR Sources - each must be named when, "Placed into service.    ("buttonpress" would be placed on the same line as Port J ISR  ...  assumes Port J does not provide "bit-type" interrupts)

I don't find this (important) function w/in your code listing: "GPIOIntTypeSet()."    

Suggested parameters for that function (may) include: "GPIO_PORTJ_BASE, GPIO_PIN_0,  GPIO_RISING (or FALLING)_EDGE (or Level)."

SW-TM4C-DRL "User Guide" greatly details - aiding user comfort, speed, and understanding...   (and provides "reasonable" examples.)     (yet "ducks the hard ones" - apparently so that "unwanted/eased forum downgrades (i.e. excise of (LIKE) may be implemented...)

For reasons "unknown" (even after the alleged forum "upgrade") I cannot edit the above.

Here are detailed illustrations of how, "our Start-Up file" is managed.    (adapted to your purposes - note that I've added "int" to your function's name to reinforce its use as an Interrupt!)

// External declarations for the interrupt handlers used by the application.
//
//*****************************************************************************
extern void IntDefaultHandler(void);
extern void intbuttonpress(void); // You must enter this - as shown here
.
.
.
// The vector table. Note that the proper constructs must be placed on this to
// ensure that it ends up at physical address 0x0000.0000.
//
//*****************************************************************************
__root const uVectorEntry __vector_table[] @ ".intvec" =
{
{ .ulPtr = (unsigned long)pulStack + sizeof(pulStack) },
// The initial stack pointer
ResetISR, // The reset handler
NmiSR, // The NMI handler
FaultISR, // The hard fault handler
IntDefaultHandler, // The MPU fault handler
IntDefaultHandler, // The bus fault handler
IntDefaultHandler, // The usage fault handler
.
.
.
Intbuttonpress,            // GPIO Port J
IntDefaultHandler,         // GPIO Port K
IntDefaultHandler,         // GPIO Port L

Suspect that the post above - amplified by herein - should get you, "On the Air!"   (at least interrupt wise...)

I would AVOID the use of IntRegister() as it complicates & provides little benefit in (many) cases...    Simple placement w/in the Start-Up file - as directed - leads to interrupt's eased success!

Yes i've done the exact same thing in the startup file as you mentioned above. In int main() i have made the following changes as shown below.

int main(void)
{
    g_ui32SysClock = MAP_SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ |SYSCTL_OSC_MAIN |SYSCTL_USE_PLL |SYSCTL_CFG_VCO_480), 120000000);

    //*****************************************************************//
    //                      Configure the LED pin                      //

    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPION);
    GPIOPinTypeGPIOOutput(GPIO_PORTN_BASE, GPIO_PIN_0);

    //*****************************************************************//

    //****************************************************************//
    //                       Configure the Switch                     //

    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOJ);
    GPIODirModeSet(GPIO_PORTJ_BASE, GPIO_PIN_0, GPIO_DIR_MODE_IN);
    GPIOPadConfigSet(GPIO_PORTJ_BASE, GPIO_PIN_0, GPIO_STRENGTH_2MA,GPIO_PIN_TYPE_STD_WPU);

    //*****************************************************************//

    //*****************************************************************//
    //                      Enabling the Interrupts                    //
    
    IntMasterEnable();
    IntEnable(INT_GPIOJ);
    GPIOIntTypeSet(GPIO_PORTJ_BASE, GPIO_PIN_0, GPIO_FALLING_EDGE);

    //*****************************************************************//

    while(1)
    {

    }

	return 0;
}

And the buttonpress() routine is present in the main.c which includes the following code as shown.

void buttonpress(void)
{
    if(GPIOPinRead(GPIO_PORTJ_BASE, GPIO_PIN_0) == 0)
    {
        GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_0, GPIO_PIN_0);
        for(ui32Loop = 0; ui32Loop < 200000; ui32Loop++)
        {
        }
        GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_0, 0x0);
        for(ui32Loop = 0; ui32Loop < 200000; ui32Loop++)
        {
        }
    }
}

is the flow correct?

cb1_mobile said:

Note that for clarity - myself/others (often) "prefix" an ISR w/"int" - which well denotes such Interrupt Role. My (sample) code for you followed that practice - if you "mix" intbuttonpress and buttonpress - errors should result and MCU confusion reigns... (along w/hapless helpers...)

I did not understand what you mean to say here? 

Can you explain it once more in clearer words?

Thank you!

cb1_mobile said:

First order would see your, "Testing of the switch signal "reaching" PJ0 (@ the MCU - be careful) and that PJ0 transitions from ~3V3 to Gnd - when the switch is pressed/held. (the 3V3 results from your enabling of the "WPU" (weak pull up) internal to the MCU)

I checked the voltage on the PJ0 pin of the microcontroller. It's changing the state from 3V3 to GND whenever the button is pressed. 

cb1_mobile said:

We note your use of, "GPIODirModeSet()." You may set PJ0 to serve as a GPIO Input via another API function

I also changed this and used 

GPIOPinTypeGPIOInput(GPIO_PORTJ_BASE,GPIO_PIN_0);

to make GPIO pin as the input. 

In  the buttonpress() ISR,right now i'm blinking the on board LED for debugging but the execution doesn't enters the ISR. 

Nishit said:

Thank you for your quick and astute responses whenever any questions are asked. 

Thank you for your kindness & (earlier) persistence in accepting some/slight tech direction.

It is noted that you changed the code from, "Falling Edge Detect" to "GPIO Low Level."     Now such "Level Detect" - while sustained - is likely to cause (near) continuous, "Return Entry to your "button-press" ISR!"    Is that (really) what you desire?    The "Edge Detect" method avoids such.

While your kind remark IS appreciated - the award of, "Verified Answer" has "escaped" any/all of my posts.     (In absence of the "exiled LIKE" button - such "Verify Reward" (applied to the "helper's" post(s)) proves most useful...