Tm4c129 - Interrupt Button

Mathieu L.

Other Parts Discussed in Thread: ENERGIA

Hi,

I wrote a short programm to light a led when I press the User 1 button, the logic "seem" right but the led isn't lighting up. What I got wrong?

#include <stdbool.h>
#include <stdint.h>
#include "inc/tm4c129xnczad.h"
#include "inc/hw_memmap.h"
#include "inc/hw_nvic.h"
#include "inc/hw_types.h"
#include "driverlib/sysctl.h"
#include "driverlib/gpio.h"


void button_press(void){
    GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_1, GPIO_PIN_1);
	SysCtlDelay(10000);
	GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_1, 0);
    SysCtlDelay(10000);
    GPIOIntClear(GPIO_PORTJ_BASE,GPIO_INT_PIN_0);
}

int main(void) {
	//clock init
	SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ | SYSCTL_OSC_MAIN | SYSCTL_USE_PLL | SYSCTL_CFG_VCO_480), 120000000);

	//button clock GPIO init
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOJ);
	while(!(SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOJ)));

	//led clock GPIO init
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPION);
	while(!(SysCtlPeripheralReady(SYSCTL_PERIPH_GPION)));

	//Led init
    GPIOPinTypeGPIOOutput(GPIO_PORTN_BASE,GPIO_PIN_1);
    //button init
	GPIOPinTypeGPIOInput(GPIO_PORTJ_BASE,GPIO_PIN_0);
	
	//interrupt set-up
	GPIOIntTypeSet(GPIO_PORTJ_BASE,GPIO_PIN_0,GPIO_FALLING_EDGE);
	GPIOIntRegister(GPIO_PORTJ_BASE,button_press);
	GPIOIntEnable(GPIO_PORTJ_BASE,GPIO_INT_PIN_0);


	//loop for ever waiting for the button to be pressed.
	while(1){

	}

}

I got questions upon the choice of Int Type. In the dev kit datasheet. the button USR 1 is connected to ground so it is logical to check for Falling_Edge right? Also I am not sure about the interrupt function(the interrupt function is correctly written in the interrup vector table), such delay aren"t too long?

over 10 years ago

0 Amit Ashara over 10 years ago

TI__Guru**** 244380 points

Hello Mathieu,

To detect a falling edge the signal has to be high. You would need to first enable the Pull Up of the GPIO.

Also you would need to enable the interrupt in the NVIC using IntEnable(INT_GPIOJ) for the interrupt to be processed by the NVIC in the CPU.

Regards
Amit

0 Mathieu L. over 10 years ago in reply to Amit Ashara

Expert 1630 points

Hi,

but doesn`t

GPIOIntRegister(GPIO_PORTJ_BASE,button_press);
GPIOIntEnable(GPIO_PORTJ_BASE,GPIO_INT_PIN_0);

enable the interrupt?

0 Mathieu L. over 10 years ago in reply to Mathieu L.

Expert 1630 points

Hi,
I only added the line
GPIOPadConfigSet(GPIO_PORTJ_BASE,GPIO_PIN_0,GPIO_STRENGTH_2MA, GPIO_PIN_TYPE_STD_WPU);
and it worked
IntEnable(INT_GPIOJ) seem to be not necessary because it worked with out the line.

0 Luis Afonso over 10 years ago in reply to Mathieu L.

Guru 20670 points

Mathieu L. said:
GPIOPadConfigSet(GPIO_PORTJ_BASE,GPIO_PIN_0,GPIO_STRENGTH_2MA, GPIO_PIN_TYPE_STD_WPU);

The 4th parameter configures the pin to have a weak pull up like Amit said hence why it worked.

Amit also suggested IntEnable() because it is needed (but there is more to it, read on)! You always need to enable the interrupt this way but... when you use GPIOIntRegister() (and others similar like TimerIntRegister() ) it simply calls with correct parameters IntRegister() (from the NVIC part of the API) and IntEnable() <- this is why your code still worked.
Just wanted to explain this part :)

0 Amit Ashara over 10 years ago in reply to Luis Afonso

TI__Guru**** 244380 points

Hello Luis,

An important thing to note is that when the IntRegister API are called the interrupt vector table is located to SRAM. Does the user want to lose 2K of precious SRAM!!!

Regards
Amit

0 Luis Afonso over 10 years ago in reply to Amit Ashara

Guru 20670 points

Yea, it has that too, thanks for the addition Amit.

But when I make my own APIs that use interrupts I always have to use it unfortunately... if there was already default names for each vector ISR I would not need to use IntRegister (suggestion). Or else I need to remember to edit also the startup and when I adapt them to work under energia that is not possible (so I always need to use IntRegister)

0 cb1_mobile over 10 years ago in reply to Luis Afonso

Guru 117855 points

It appears that "energia" does so "little" - yet demands so "much!"
Poster - and even the talented Luis - may wish to follow Amit's great guidance & "gain back" their "precious" Ram.
May we note that poster's "Self Awarded" Verify will surely "bite him" - sooner rather than later. Rejecting Amit's guidance is never good - trading a "so limited & temporary" fix - for an established, safe one - makes NO sense!

0 Luis Afonso over 10 years ago in reply to cb1_mobile

Guru 20670 points

"It appears that "energia" does so "little" - yet demands so "much!" "
So true... -.-
But it's a high school that uses it so it's ok for me (now when it's above that Energia/Arduino is the only way... ).

Lately I have tried to keep all the RAM but now I keep forgetting to add the ISR names to the vector table :p

0 cb1_mobile over 10 years ago in reply to Luis Afonso

Guru 117855 points

Luis Afonso said:
I keep forgetting to add the ISR names to the vector table

And won't your faulting program very well "signal" that forgetfulness?

Bad habits are not quick/easy to break/replace. Yet - dreaded, "ram-shrink" (inflicting an already limited resource) may just provide the needed motivation...

(self-awarded "verifies" should exist only in Ram - so that they "die" when power is removed...) (and poster has returned to his/her senses)

0 Robert Adsett over 10 years ago in reply to Luis Afonso

Guru 27665 points

Luis Afonso said:
if there was already default names for each vector ISR I would not need to use IntRegister (suggestion). Or else I need to remember to edit also the startup and when I adapt them to work under energia that is not possible (so I always need to use IntRegister)

Luis Afonso said:
Lately I have tried to keep all the RAM but now I keep forgetting to add the ISR names to the vector table :p

It pays to know what your tools (and standard professional tools) are capable of.

A standard linker will be able to define 'weak symbols', the terminology will differ but the concept is the same from vendor to vendor.

The interrupt table is filled with standard names for each interrupt function. These are either defined separately as functions or aliased to a single standard default function (the latter probably being preferable). These symbols are defined as weak meaning they are tentative placeholders used only if no other definitions are available.

The actual interrupt functions are defined in your program using the same names. These are normal or strong definitions

When the program is linked the strong symbols replace the weak (with no error) so you end up with a default routine for any interrupt you have not replaced and your replacement (with a standard name) for any that you define.

Hand holding can be comforting when you start to walk but as soon as you have to step off of the paved path you are likely to find you need both hands free.

Robert

0 cb1 over 10 years ago in reply to Robert Adsett

Guru 47900 points

Again, "Knocked out of the Park!" (I need 9 more "IDs" to properly "Like" that one!)

Your "wrap up" sentence says it all - in an especially memorable & compelling manner. Simply inspired - Happy 4th (should that apply!)

0 Mathieu L. over 10 years ago in reply to Amit Ashara

Expert 1630 points

You talk about GPIOintRegister function?

0 Amit Ashara over 10 years ago in reply to Mathieu L.

TI__Guru**** 244380 points

Hello Mathieu

Yes. IntRegister is the generic function from the interrupt.c which is called by the driverlib

Regards
Amit

0 Robert Adsett over 10 years ago in reply to cb1

Guru 27665 points

Thank you kindly.

Robert

Had our fireworks last night (for the occasion formerly known as Dominion Day)

0 cb1 over 10 years ago in reply to Robert Adsett

Guru 47900 points

Robert Adsett said:
Had our fireworks last night

In our beloved mid-west "big city" we (almost) can hear the fireworks! (when not drowned out by gunfire, giant trucks, trains or 747s on final...)

I can (just) recall Maurice, "Le Rocket" beating the brains out of our (past) beloved NY Rangers... Again - great job...

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Tm4c129 - Interrupt Button