MPC5744P PIT Interrupt problem

[admin]

Original Content posted by David Chung.

I'm writing a simple project for Panther that uses the PIT0 ISR to to toggle a GPIO pin. I use the 160MHz PLL as the clock source, initialize PIT0, enable PIT0 interrupts in the NVIC, add the PIT0_ISR address to the interrupt table. In the ISR, I clear the interrupt flag and toggle the GPIO pin.  The problem is for some reason the program only enters the ISR around 2 to 4 times before never entering again.  I can see that PIT_0.TFLG0 is set so an interrupt is called by PIT0, but it's not being handled. The PIT0 init code is shown:

void PIT0_init(uint32_t LDVAL) {

  volatile uint32_t dummy = 0;

  PIT_0.TIMER[0].LDVAL.R = LDVAL; /* Load # PIT clocks to count */

  PIT_0.TIMER[0].TCTRL.B.TIE = 1; /* Enable interrupt */

  INTC_0.PSR[226].B.PRIN = 10; /* IRQ priority = 10 (31 highest) */

  dummy = INTC_0.PSR[226].R;

  PIT_0.TIMER[0].TCTRL.B.TEN = 1; /* enable channel */

}

The ISR is as follows:

void PIT0_isr(void) {

  LED1 = ~LED1;             /* Toggle LED1 port */

   PIT_0.TIMER[0].TFLG.R |= 1;  /* Clear interrupt flag. w1c */

}

Anyone know the cause of this issue?

[martin_kovar]

Hi David,

look at this example. There is shown how to set PIT.

Example MPC5744P PinToggleStationery S32DS

At the first sight, you did not correctly configure INTC_0.PSR register. You only set priority, but you did not choose the core, which will handle the interrupt.

Regards,

Martin

[nathan_]

Hello,I just download the example you uploaded and tried to debug it.

I want to use the PIT module, so I made a little change in the code. My project is attached.

I met a problem when I debug it. After I press the "resume", the code will fall into a function named "dummy" and do not go on, The picture is also attached, named "dummy"

Then I set a breakpoint before the while loop, I find out the code goes well before the while loop, which means in the initiation the problem did not occur.

Could you please help me to fix the problem? I really need to work out this problem and use the PIT module.

Thank you. 

[martin_kovar]

Hello Nathan,

you do not have installed correct interrupt service routine. Please see intc_SW_mode_isr_vectors_MPC5744P.c file in my project and add the interrupt service routine at correct address (Vector 226).

Regards,

Martin

[nathan_]

I can not understand the set for PLL0 in the example.

According to the MPC5744P datasheet, the max of PLL0_PHI0 is 200MHz, but the example the PLL0 is set to 400MHz by the following code:

PLLDIG.PLL0DV.R = 0x58021014;     // PREDIV =  1, MFD = 20, RFDPHI = 2, RFDPHI1 = 11

Is this correct?

[martin_kovar]

Hello,

the calculation seems to be incorrect. Correct value for 200MHz with 40MHz crystal is:

PLLDIG.PLL0DV.R = 0x3002100A // PREDIV =  1, MFD = 10, RFDPHI = 2, RFDPHI1 = 6

Regards,

Martin

[nathan_]

The problem has been solved. Thank you so much !