Distinguish between power being cycled and the nPORRST line being driven low

David Sabol

Other Parts Discussed in Thread: HALCOGEN, TMS570LS0332

Hi,

I am using the TMS570LS0332 and Halcogen 4.2.

I see in sys_startup.c that it checks for different reset conditions. However, it looks like the if statement below is true whether power is cycled or if the nPORRST line is driven low. Is there any way to tell the difference between the two?

if ((SYS_EXCEPTION & POWERON_RESET) != 0U)
    {
/* USER CODE BEGIN (12) */
/* USER CODE END */
        
        /* clear all reset status flags */
        SYS_EXCEPTION = 0xFFFFU;

/* USER CODE BEGIN (13) */
/* USER CODE END */

        /* Workaround for Errata CORTEXR4 66 */
        _errata_CORTEXR4_66_();
    
/* USER CODE BEGIN (14) */
/* USER CODE END */

        /* continue with normal start-up sequence */
    }

Thanks,

David

over 10 years ago

0 Zhaohong Zhang over 10 years ago

TI__Mastermind 22715 points

David,

You can not tell the difference from system status registers. The RAM content will be lost during a power cycle.

Thanks and regards,

Zhaohong

0 David Sabol over 10 years ago in reply to Zhaohong Zhang

Genius 4850 points

Are there any registers / areas of memory that will retain their contents then the nPORRST line is driven low, but will lose the contents and come up in an unknown state when a hard power cycle is applied?

It looks like RAM is not initialized until after it checks what caused the reset, so I'm wondering if I could set a register / memory location to some known value and then check that to see the difference.

Thanks,
David

0 Zhaohong Zhang over 10 years ago in reply to David Sabol

TI__Mastermind 22715 points

All the system and peripheral control registers has a default value (the value you see after reset.). You can check them to see if they match the default value after reset.

Thanks,

Zhaohong

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Distinguish between power being cycled and the nPORRST line being driven low