MSP430F6779A: About UCS Module Fail-Safe Operation

Hi Tink

May I know the reason of XT1 crystal not stable 600 ms after the DVCC is applied?

from the UG description,

a crystal fault automatically causes the FLL reference source, FLLREFCLK, to be sourced by the REFO.

Hi,

for 600 milliseconds is characteristic of the crystal oscillator circuit. After supplying voltage from 0 V to 3.3 V

I also have some experiments on clock failure states with some conditions of DVCC and AUXVCC1 below.

1) When connecting and disconnecting the DVCC 0 to 3.3 V power supply, connect AUXVCC1 to 3.3 C continuously.
Result: No oscillator failure detected.

2) When connecting and disconnecting the DVCC 0 to 3.3 V power supply, connect AUXVCC1 to 1.4 V and below.
Result: Oscillator failure detected.

Why is an oscillator failure detected (OFFG = 1
XT1LFOFFG = 1) with AUXVCC1 voltage 1.4 and below?

From all of the above my discussion was about suspected cause (clock source failure) of the problem. Where I found the MCU get stuck (the device not start) in the actual use field. But it cannot be reproduced in a laboratory.

This cannot use the debugger to debug where the code is stuck. (becuase the debugger reset the program counter)

Symptoms of the bug were just checked with the H/W pin
(device does not start).
Vcore pin = 1.42 V (core level 0 AM)
Reset pin = 3.3 V

some related issues i discussed.

e2e.ti.com/.../5051888

Hi,

I have another question about code below?

int _system_pre_init(void)
{
    /* Insert your low-level initializations here */
    __disable_interrupt();
    WDTCTL = WDTPW+WDTHOLD;

    // Clear RTCHOLD Bit after reset
    RTCCTL0_H = RTCKEY_H;     // unlock
    RTCCTL1 &= ~RTCHOLD;      // release RTC
    RTCCTL0_H = 0x00;         // lock
    
}

Is it correct to clear RTC hold bit in system_pre_init?

Are there any problems/risks when the RTC hold bit is clear in system_pre_init (DVCC and crystal are not yet stable, related to MCU stuck or not)?

Hi Tink

These is _disable_interrupt () at the beginning of the code.

I think all interrupt is disable here.

I don't have idea how to release RTC here because the interrupt is disable

Thanks