Starterware/MSP432P401R: Using Systick as a Timer

Duane Shelton said:

unresolved symbol SysTick_Handler, first referenced in ./startup_msp432p401r_ccs.obj Lab4 C/C++ Problem

IMHO this means that the name of your Systick handler routine does not match that one given/expected in the startup code. I don't have the Starterware (because I don't have a MSP432 board) but usually it is an assembler file named "startup_xxx.s" - with "xxx" as placeholder for a MCU-specific string.

BTW, the SysTick peripheral is common to all Cortex M3/M4 implementations, so you can use any example code you find - not just TI-specific. However, the SysTick timer is kept rather simple, it is designed for the very purpose of being a system tick timer.

Hi Duane,

 This is the example code that you are using - systick_interrupt_gpio_blink, am I correct??

My guess is that you removed the  "SysTick_Handler" in main.c

void SysTick_Handler(void)
{
    MAP_GPIO_toggleOutputOnPin(GPIO_PORT_P1, GPIO_PIN0);
}

So you will also need to remove it in your startup_msp432p401r_ccs.c, for example:

From:

#pragma RETAIN(interruptVectors)
#pragma DATA_SECTION(interruptVectors, ".intvecs")
void (* const interruptVectors[])(void) =
{
    (void (*)(void))((uint32_t)&__STACK_END),
                                            /* The initial stack pointer */
    resetISR,                               /* The reset handler         */
    nmiISR,                                 /* The NMI handler           */
    faultISR,                               /* The hard fault handler    */
    defaultISR,                             /* The MPU fault handler     */
    defaultISR,                             /* The bus fault handler     */
    defaultISR,                             /* The usage fault handler   */
    0,                                      /* Reserved                  */
    0,                                      /* Reserved                  */
    0,                                      /* Reserved                  */
    0,                                      /* Reserved                  */
    defaultISR,                             /* SVCall handler            */
    defaultISR,                             /* Debug monitor handler     */
    0,                                      /* Reserved                  */
    defaultISR,                             /* The PendSV handler        */
    SysTick_Handler,                             /* The SysTick handler       */

To:

#pragma RETAIN(interruptVectors)
#pragma DATA_SECTION(interruptVectors, ".intvecs")
void (* const interruptVectors[])(void) =
{
    (void (*)(void))((uint32_t)&__STACK_END),
                                            /* The initial stack pointer */
    resetISR,                               /* The reset handler         */
    nmiISR,                                 /* The NMI handler           */
    faultISR,                               /* The hard fault handler    */
    defaultISR,                             /* The MPU fault handler     */
    defaultISR,                             /* The bus fault handler     */
    defaultISR,                             /* The usage fault handler   */
    0,                                      /* Reserved                  */
    0,                                      /* Reserved                  */
    0,                                      /* Reserved                  */
    0,                                      /* Reserved                  */
    defaultISR,                             /* SVCall handler            */
    defaultISR,                             /* Debug monitor handler     */
    0,                                      /* Reserved                  */
    defaultISR,                             /* The PendSV handler        */
    defaultISR,                             /* The SysTick handler       */

Hopefully this helps.

  David

That's what I was doing.  I changed the startup file as you suggested and it's working now.

Thanks for your help!

Duane