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µVISION DEBUGGER: Get "No Synchronization" Using SWO on SI3MU1xx Board

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Information in this knowledgebase article applies to:

• MDK-ARM V4.53

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SYMPTOM

When debugging the Silicon Labs BLINKY and RTX_BLINKY example projects with the SWO Trace option enabled, the Trace status displays Running... for about 5 seconds then displays No Synchronization.

CAUSE

The watchdog timer is turned on by default when the MCU is reset, and is not being disabled in the example program.

RESOLUTION

In the BLINKY.C module, modify the mySystemInit() function with the following code to disable the watchdog timer:

void mySystemInit() {

/*----------------------------------------------------------------------------
        Disable watchdog timer sequence for debugging
 *----------------------------------------------------------------------------*/
  SI32_WDTIMER_0->WDTKEY.KEY = SI32_WDTIMER_A_WDTKEY_KEY_ATTN_U32;     /* Unlock Key I/F  */
  SI32_WDTIMER_0->WDTKEY.KEY = SI32_WDTIMER_A_WDTKEY_KEY_DISABLE_U32;  /* Disable Wdog    */

//  __NOP();
}

Note that the __NOP() can be deleted.

Re-build the project, and the SWO trace should now run as expected.

STATUS

These example projects will be updated in an upcoming release.

Last Reviewed: Friday, June 29, 2012

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