Kinetis Microcontrollers中的主题 K20 PIT ISR configuration problem

K20 PIT ISR configuration problem

yvesb — Thu, 27 Feb 2014 14:56:22 GMT

Hi,

I am trying to configure an isr on the K20P100 dev kit (TWRK20D) to blink a LED, using the demo_gpio.c example as basis.

Here's my init routine called by main:

void _init_PIT()

{

// enable PIT clock

SIM_SCGC6 |= SIM_SCGC6_PIT_MASK;

// enable PIT clock, freeze in debug

PIT_MCR = 0x01;

// set PIT 3

PIT_LDVAL3 = 5000000; // setup timer for 5000000 cycles

PIT_TCTRL3 = PIT_TCTRL_TIE_MASK // enable timer interrupt

| PIT_TCTRL_TEN_MASK; // enable timer

NVICICPR2 |= 1 << (71%32);

NVICISER2 |= 1 << (71%32);

}

in the isr.h, I added this:

#undef VECTOR_87

#define VECTOR_87 isr_pit3

extern void isr_pit3(void);

then I added in demo_gpio.c:

void isr_pit3(void)

{

PIT_TFLG3 |= 1;

GPIOC_PTOR |= 1<<PIN_LED_2;

}

This code doesn't work, execution never goes to isr_pit3() function.

Am I missing something?

Regards,

Yves

yvesb — Thu, 27 Feb 2014 15:58:59 GMT

Just noticed that if I use the debug terminal, it displays the following message:

****default_isr entered on vector 87*****

87 is the vector for PIT3. but I don't understand why this message is displayed

yvesb — Thu, 27 Feb 2014 16:26:58 GMT

The problem was that declarations in isr.h are ignored and must be written in vectors.h.

However, this doesn't explain why the isr from the example, not declared in vectors.h, worked!!