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MSP430I2041: RST pin doesn't work

Part Number: MSP430I2041
Other Parts Discussed in Thread: TIDM-SERVER-PWR-MON, MSP430I2040

My customer made a smart plug by referring to the TIDM-SERVER-PWR-MON.

It measures AC voltage, power and etc.

When the board is connected to an one outlet of individual switch multi-tap as shown below and the switch of another outlet is repeatedly turned on/off, sometimes the MCU doesn't work and seems to be frozen.

At this time, MSP430 was not reset even though a signal changing from Low to High was input to the RST/NMI pin.

In order to restart the MCU, the power must be turned off and then turned on again.

This symptom is reproduced the same in the TIDM-SERVER-PWR-MON.

I'd like to know why the RST pin does not work and how to recover except power off when MCU gets hang.

  • Hello,

    Sorry for the delay.  Have you been able to find a root cause here?   

    Has the power switching been analyzed?  Is the VCC of the MSP430 going all the way to 0V when the switch is off?  Is it remaining within absolute maximum specs when switching?  Any noise that has been observed?  

    In the application, is the RST pin still configured for RST or is the functionality changed to NMI?  Sometimes the pin is switched to NMI mode for improved noise/EMI robustness and if so, then it wouldn't reset the MCU.  

    The only other issue that I'm aware of that request power cycles but can't be fixed by resets, are Latch-up events.  I'm not aware of this happening with MSP430I2040 specifically, but it's possible sometimes on other MSP430s.  If the device browns out, maybe something could be happening then too.  



  • Hello, Thank you for your reply.

    I checked VCC and the waveform below is VCC of MSP when switch is turned on/off.

    It has a lot of noise. 

    The RST pin still configured for RST in the application. 

    If the VCC is noisy as above, is there any way to improve it?

    I think some applications using AC voltage supply have this problem and solution.