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MSP430F6726A: How to monitor DVCC using PMM

Expert 2265 points
Part Number: MSP430F6726A

Hi,

1) I would like to know how to monitor whether DVCC has reached 3V using PMM (register setting, etc.).

The system frequency is 8MHz. Also, since DVCC uses a different power source than AVCC, it cannot be monitored using AVCC.

2) if you have any sample code provided by TI that corresponds to the above, please let me know.

Koki

  • Hello Koki,

    The PMM is described in the MSP430x5xx_x6xx Family User Guide.

    Regarding (1) - To the best of my knowledge, there is no direct way to do this with available functionality of the PMM module.

    Also, since DVCC uses a different power source than AVCC, it cannot be monitored using AVCC

    I'm not quite sure what you are saying here.  Can you clarify?  

    Regarding (2) -  MSP430F6726A example code is available in the TIREX (TI Resource Explorer).  However, after first checking, I don't see any examples using the PMM.

    Can you provide a few details about your application or reason for needing to know when DVCC has reached 3V?

  • Hi, Dennis

    I'm not quite sure what you are saying here.  Can you clarify?  

    I'm sorry, forget the quote. I want to know how to to monitor whether the voltage of DVcc reaches 3V. 

    Regarding (1) - To the best of my knowledge, there is no direct way to do this with available functionality of the PMM module.

    In the data sheet, it seems possible to set a threshold level of 3V or higher. Please tell me the reason why MCU cannot monitor 3V in PMM.

    Also if there is a description in the document, please let me know as well.

    Can you provide a few details about your application or reason for needing to know when DVCC has reached 3V?

    I am confirming the use of 3V monitoring with customer. I will contact you as soon as I can hear from customer.

    Thanks,

    Koki

  • Hi Koki,

    Ok, I understand now. Yes,  according to section 2.2.2.2 in the user's guide, it would be possible using the SVMHE and SVSMHRRL bits.  I took a look to see if there is any example code that demonstrates this, but didn't find anything.  It doesn't look like it would be too difficult to setup though.

  • Hi, Dennis

    1) The PMM detects when the DVcc becomes 3V or less after the power is turned on, isn't it? We want to make sure it's over DVcc 3V, is it possible?

    2) If 1) is YES, I have additional question about PM MCOREV. Since it is a battery-powered product, it is necessary to save power as much as possible.
    Since the CPU clock is operated at 8MHz, it is used at PMMCOREV = 00. Is it okay to understand that I should set PMMCOREV = 11 in the initial settings and change the setting to PMMCOREV = 00 after confirming that DVCC has risen to 3V or higher?

    Thanks,

  • Hi Koki,

    Yes, based on the second table above, it looks like SVSMHRRL  can be  '110' or '111', but, notice the values in this table range from 2.85v to 3.15v.  This means from device to device and across temperature, some devices may detect VCC @ 2.85v, and others won't detect until VCC = 3.15v.

    Since this is battery powered device and the customer is operating at only 8MHz, PMMCOREV can be set to '00'.  Not sure why customer would need to set it = '11', unless they intend to operate >8MHz.

    The customer can then select the appropriate SVSHRVL and SVSMHRRL values to monitor VCC.  The SVM can generate an interrupt when VCC < SVSMHRRL, but I would suggest not enabling this interrupt during startup and only check the flag, SVMHIFG.  Once VCC > SVSMHRRL, the flag should remain cleared.

    Does this help?

  • Hi, Dennis

    Since this is battery powered device and the customer is operating at only 8MHz, PMMCOREV can be set to '00'.  Not sure why customer would need to set it = '11', unless they intend to operate >8MHz.

    If I set SVSMHRRL to 6 or 7 from UG Figure 4-3, I need to set PMMCOREVx to 11, right?

    I think SVMHIFG is a flag that detects the falling edge of DVcc.Is it possible for DVcc to detect the rise of 3V by monitoring SVMHVLRIFG?

    Also, I think it is necessary to set PMMCOREVx = 11 for 3V detection of DVCC. So, if PMMCOREVx = 11 is set and DVcc 3V is detected, is it okay to change it to PMMCOREV = 00?

    Thanks,