MSP430FR2422: Issue with LPM 3.5 wakeup

prashanth k b

Part Number: MSP430FR2422

We have configured LPM 3.5 with wakeup source as RTC overflow. We check the source of wakeup by reading the SYSRSTIV location which returns the value 0x08(i.e wake up from LPM3.5). It is working fine in several thousand boards. In one of the microcontroller when RTC overflows and the device wakes up from LPM 3.5 , SYSRSTIV register reads the value 0x02(i.e Brownout Reset). This is happening consistently in one particular microcontroller.

Note: We have replaced this microcontroller in different boards which were working fine, we have found that problem is consistent as mentioned above.

over 1 year ago

0 Eason Zhou over 1 year ago

TI__Mastermind 32870 points

Can you help test the timing when the MCU with issue enter LPM3.5 and go to main function? You can use GPIO to do the test?

How do you find this problem? Does the device have other problems?

0 prashanth k b over 1 year ago in reply to Eason Zhou

Prodigy 70 points

A voltage divider is monitored using an ADC pin, below a threshold voltage MCU enters into LPM3.5 (only RTC overflow to wake up from LPM).

Eason Zhou said:
Can you help test the timing when the MCU with issue enter LPM3.5 and go to main function?

MCU enters LPM3.5 configuring RTC to two seconds overflow, Exactly after 2 seconds MCU goes to main function this is verified with DSO also RTC overflow interrupt flag is set which is verified by printing .

Eason Zhou said:
How do you find this problem?

SYSRSTIV register which supposed to give a value of 0x08 is now giving 0x02 in this particular MCU.

Note :this issue is found only in one particular MCU .

0 Eason Zhou over 1 year ago in reply to prashanth k b

TI__Mastermind 32870 points

I mean whether this problem will affect the MCU performance.

Normally, we will take it as PPM issue. But from my experience, it is really hard for TI to track the root reason.

0 prashanth k b over 1 year ago in reply to Eason Zhou

Prodigy 70 points

Thanks for the reply. Could you please provide some clarification.

1.On LPM wakeup because of RTC overflow can SYSRSTIV register have the value of 0x02 in a perfectly working controller?

I have attached snapshots from MSP430FRxx user guide and MSP430fr2422 datasheet. The User guide says "A wakeup from LPM 3.5 can generate a BOR" , whereas according to the datasheet if BOR occurs SYSRSTIV should contain 0x02 and if device wakeup from LPM 3.5 then SYSRSTIV should have 0x08.

MSP430FRXX Users guide

MSP430FR2422 Datasheet

2. Can I ignore this issue considering it as a PPM issue?

+1 Eason Zhou over 1 year ago in reply to prashanth k b

TI__Mastermind 32870 points

1. SYSRSTIV register should not be the value of 0x02 in a perfectly working controller because of RTC overflow.

2. For industry product the PPM is about 100 ppm. For more information, you can refer to this:https://www.ti.com/support-quality/reliability/DPPM-sample-size-calculator.html

3. If you want TI to do the FA, you need to consult TI sales.

0 prashanth k b over 1 year ago in reply to Eason Zhou

Prodigy 70 points

Thank you. If this issue recurs we will contact for FA.

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MSP430FR2422: Issue with LPM 3.5 wakeup