C6713 GPIO Hardware Interrupts Question

Jorge Cifuentes

Hi!

I am writing a program that runs two ISR's, each assigned to an external interrupt of the GPIO (EXT_INT6 and EXT_INT7). We are going to interface this connection with a microcontroller and the interrupts are programmed to be active on a low to high transition. Right know I am only doing tests with the Voltage and GND signals from the C6713 DSK on a protoboard. I connect the cable to GND and as soon as I unplug it from GND, the interrupt becomes active. If I then connect the cable to voltage, the interrupt does not work. Then, my interrupts only work when the cable goes from GND to being unplugged... I would like to know why is this happening and if it safe to test this "interrupt simulation" (instead of using a cable that i manually plug and unplug) with a switch that connects to GND or Voltage the GPIO pin.

Here is my code:

#include <dsk6713.h>
#include <csl_gpio.h>
#include <csl_gpiohal.h>
#include <csl_irq.h>
#include <csl.h>
#include <stdio.h>
#include "DSPBIOScfg.h"

int pin8 = -1;
int pin9 = -1;
int pin10 = -1;
int pin11 = -1;
int pin12 = -1;
int pin13 = -1;
int pin14 = -1;
int pin15 = -1;

int flag = 0;

GPIO_Handle gpio_handle; /* handle para el GPIO */

//Configuración de los registros del GPIO

GPIO_Config gpio_config = {

    0x00000000, // gpgc = Modo Passthrough de Interrupciones y control directo sobre GP0

    0x0000FFFF, // gpen = Todos los pines de GPIO de 0 a 15 habilitados

    0x00000000, // gdir = Todos los pines de GPIO como entradas

    0x00000000, // gpval = Guarda el nivel lógico de los pines

    0x00000000, // gphm all interrupts disabled for io pins

    0x00000000, // gplm all interrupts to cpu or edma disabled

    0x00000000 // gppol -- default state */

};

void leerDatosIzq();
void leerDatosDer();

void main() {

    IRQ_globalDisable();

    DSK6713_init();
    DSK6713_LED_init();

    gpio_handle = GPIO_open( GPIO_DEV0, GPIO_OPEN_RESET );

    GPIO_config(gpio_handle,&gpio_config);

    IRQ_map(IRQ_EVT_EXTINT7, 7);
    IRQ_map(IRQ_EVT_EXTINT6, 6);
    IRQ_reset(IRQ_EVT_EXTINT7);
    IRQ_reset(IRQ_EVT_EXTINT6);
    IRQ_globalEnable();
    IRQ_nmiEnable();
    IRQ_enable(IRQ_EVT_EXTINT7);
    IRQ_enable(IRQ_EVT_EXTINT6);

    while (1) {
        DSK6713_LED_on(0);
        DSK6713_LED_off(3);

        if (flag == 1) {

            printf("\nPIN 8 --> %d\n", pin8);
            printf("\nPIN 9 --> %d\n", pin9);
            printf("\nPIN 10 --> %d\n", pin10);
            printf("\nPIN 11 --> %d\n", pin11);
            printf("\nPIN 12 --> %d\n", pin12);
            printf("\nPIN 13 --> %d\n", pin13);
            printf("\nPIN 14 --> %d\n", pin14);
            printf("\nPIN 15 --> %d\n", pin15);

            flag = 0;
        }

    }

}

void leerDatosIzq(){


    pin8 = GPIO_pinRead (gpio_handle,GPIO_PIN8);
    pin9 = GPIO_pinRead (gpio_handle,GPIO_PIN9);
    pin10 = GPIO_pinRead (gpio_handle,GPIO_PIN10);
    pin11 = GPIO_pinRead (gpio_handle,GPIO_PIN11);

    pin12 = GPIO_pinRead (gpio_handle,GPIO_PIN12);
    pin13 = GPIO_pinRead (gpio_handle,GPIO_PIN13);
    pin14 = GPIO_pinRead (gpio_handle,GPIO_PIN14);
    pin15 = GPIO_pinRead (gpio_handle,GPIO_PIN15);

    DSK6713_LED_off(0);
    DSK6713_LED_on(3);
    flag = 1;

}

void leerDatosDer(){

    pin8 = GPIO_pinRead (gpio_handle,GPIO_PIN8);
    pin9 = GPIO_pinRead (gpio_handle,GPIO_PIN9);
    pin10 = GPIO_pinRead (gpio_handle,GPIO_PIN10);
    pin11 = GPIO_pinRead (gpio_handle,GPIO_PIN11);

    pin12 = GPIO_pinRead (gpio_handle,GPIO_PIN12);
    pin13 = GPIO_pinRead (gpio_handle,GPIO_PIN13);
    pin14 = GPIO_pinRead (gpio_handle,GPIO_PIN14);
    pin15 = GPIO_pinRead (gpio_handle,GPIO_PIN15);

    DSK6713_LED_off(0);
    DSK6713_LED_on(3);
    flag = 1;

}

The ISR's are assigned to the last two functions (leerDatosIzq and leerDatosDer) through the DSPBIOS's Hardware Interrupt Service Routine Manager. They are assigned to HWI_INT6 and HWI_INT7. They have no monitor assigned, the checkbox "Use Dispatcher" is selected. The Arg: is the default: 0x00000000 and the interrupt mask is "self".

I am using CCS 3.3.38.2 and DSP BIOS 5.31.02.

Thanks for your help.

Jorge Cifuentes

over 15 years ago

0 tlee over 15 years ago

TI__Guru 62975 points

Jorge,

Do you measure a voltage on the pins when you are not driving them? Those pins have internal pull-ups so forcing an external logic high on them will not produce a level transition. Forcing a momentary logic low will create a transition.

-Tommy

0 Jorge Cifuentes over 15 years ago in reply to tlee

Prodigy 160 points

Thanks a lot Tommy. My program finally works!!

I didn't measure the pins for voltage but when I connected the DSP with the microcontroller everything worked fine. The program runs too fast so I can't check if it is actually the low to high transition or the high to low transition (when the pulse sent by the microcontroller goes back to a logic '0') the one that is activating the interrupt. The project was due today so we couldn't make a test program to check this.

But then, are all interrupts of the GPIO activated only from high to low transitions? If so, then it doesn't matter if I configure the interrupt to be activated on low to high transitions? They will always work with high to low transitions?

Thank you very much

Have a nice day,

Jorge Cifuentes

0 tlee over 15 years ago in reply to Jorge Cifuentes

TI__Guru 62975 points

Jorge,

The transition direction that triggers an interrupt is selectable through the GPIO module registers like GPDH.

-Tommy

0 Cryptoman over 15 years ago in reply to Jorge Cifuentes

Intellectual 870 points

Hi Jorge,

You can configure the polarity of the interrupt using gppol register. Writing a '1' to a bit position in that register, means a falling edge trigger on the corresponding GPIO port pin. Obviously, writing a '0' means falling edge.

Regards...

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C6713 GPIO Hardware Interrupts Question