TM4C1290NCPDT: Still can't get SysTick to work.

Doug Broadwell85

Part Number: TM4C1290NCPDT

I thought with the last help from this forum that I had fixed the problem with my SysTick not firing, but I was mistaken.

So I used the example code to create a simple project to test it:

/**
* main.c
*/

#include <stdbool.h>
#include <stdint.h>

#include "driverlib/gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/sysctl.h"
#include "driverlib/systick.h"

void SysTickISR(void) {

    volatile int i;

    for(i=0; i<10; i++) {
        i = i;
    }
}

int main(void)
{

    unsigned int SysClk = SysCtlClockFreqSet((SYSCTL_XTAL_20MHZ | SYSCTL_OSC_MAIN | SYSCTL_USE_OSC), 20000000);
    SysTickPeriodSet(SysClk);
    SysTickIntRegister(SysTickISR);
    IntMasterEnable();
    SysTickIntEnable();
    SysTickEnable();

    while(1) {}
}

This does not work. BTW, the example code is wrong as it doesn't have the SysTickIntRegister() command ! TivaWare_C_series_2_1_4_178.

Defective MPU chip??

Thanks, Doug

over 1 year ago

0 Charles Tsai over 1 year ago

TI__Guru**** 191206 points

Why don't you try the attached CCS project. I run it on the LaunchPad and I can see the systick interrupt. I use the example in TivaWare.

4863.systick.zip

Doug Broadwell85 said:
BTW, the example code is wrong as it doesn't have the SysTickIntRegister() command !

That is not true. The example systick.c file is only one source file. It is not a complete CCS project. You will need to plug your static interrupt vector in the startup file. Refer to the example I attach which is a complete CCS project. The vector table in the startup file is filled with vectors particularly the SysTickIntHandler().

0 Doug Broadwell85 over 1 year ago in reply to Charles Tsai

Intellectual 510 points

In my SysTick example folder the file is "interrupt.c"

0 Doug Broadwell85 over 1 year ago in reply to Doug Broadwell85

Intellectual 510 points

FYI, I found the problem and it was the MPU. VddA was running at 3.3 volts while Vdd was running at 3.1 volts. Even though 3.1 volts is within the chip's acceptable Vdd range, I infer that it doesn't want to be far off from VddA. When I raised Vdd to 3.25 volts SysTick started working correctly.

0 Doug Broadwell85 over 1 year ago in reply to Doug Broadwell85

Intellectual 510 points

Well, something strange is going on as SysTick has stopped working again. Will let you know what I find.

+1 Doug Broadwell85 over 1 year ago in reply to Doug Broadwell85

Intellectual 510 points

OK, I was correct before. There was some contamination at a high-impedance point in the Vdd power supply that had dropped the voltage back down to about 3.1 volts, when cleaned up and the voltage is back to 3.25 volts the SysTick is working again.

I see a note in the datasheet to the VddA must be 3.3 volts for the chip to work correctly, is there a similar note stating that Vdd must be close to VddA for the chip to work correctly?

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TM4C1290NCPDT: Still can't get SysTick to work.