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MSP430FR6889: MSP430FR6889 200uA in LP3.5 mode

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Replies: 9

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Part Number: MSP430FR6889

Hello!

The customer says that he use MSP430FR6889 in his project. The problem is that power consumption in LP3.5, LP4 modes is 200uA, it's to high. I've attached scheme and code (customer doesn't want to send me full project, here just a photos). Can you help me, please?

MSP430FR.zip

  • Hi Artem,

    First the screenshot you've provided shows the MSP430 is being put into LPM3 and not LPM3.5. There is a specific sequence of instructions that need to be executed to enter LPM3.5 that is described in the User's Guide and there are also examples available via MSP430Ware. The next thing I noticed is that the GPIO are being configured as inputs. It's recommended that any unused GPIO be set to output low for the lowest possible power consumption.

    Finally, the 200uA range is closer to LPM0 or LPM1 range. Are you sure the device is actually entering LPM3? For example, if a peripheral is using SMCLK and the SMCLKREQEN bit is set in the CSCTL6 register, the device will instead go to LPM0/1 where the clock is still active. Disabling the SMCLK request enable bit will keep the device from exiting a LPM when SMCLK is requested.

    Best regards,
    Caleb Overbay
  • In reply to Caleb Overbay:

    But what can you say about program on the screenshots? Do you see a problem with entering LPM3 ?

  • In reply to artem dmitriev5:

    The customer says that SMCLKREQEN bit is set by default. Also in msp430fr5889 SMCLKREQEN bit is set by default, but the client says that in this case power consumption is about 2uA.
  • In reply to artem dmitriev5:

    Can anybody help me, please?
  • In reply to artem dmitriev5:

    Hi Artem, 

    I apologize for the delay, I was out of office yesterday and unable to respond.

    artem dmitriev5
    But what can you say about program on the screenshots? Do you see a problem with entering LPM3 ?

    As I said previously, and unused GPIO needs to be in output low state to achieve the lowest power consumption possible. Additionally, anything that may be drawing power from the device's GPIO pins will also add to the current consumption. If you're attempting to enter LPM3, the code shown in the screenshots is doing it correctly.

    artem dmitriev5
    The customer says that SMCLKREQEN bit is set by default. Also in msp430fr5889 SMCLKREQEN bit is set by default, but the client says that in this case power consumption is about 2uA.

    You're correct that it's set by default. Your customer needs to verify if a module is requesting the SMCLK from LPM3. If this is the case, then the device isn't actually entering LPM3 and is most likely in an LPM0/1 state. The observed current of ~200uA seems to follow this theory. To keep modules from waking the device from LPM3, they should set the SMCLKREQEN bit to 0. This has the additional affect of disabling whatever peripherals may be attempting to use SMCLK in LPM3. 

    Best regards, 
    Caleb Overbay

  • In reply to Caleb Overbay:

    But why can msp430fr5889 enter LP state while msp430fr6889 not?

  • In reply to artem dmitriev5:

    Artem,

    artem dmitriev5
    But why can msp430fr5889 enter LP state while msp430fr6889 not?

    I'm not sure what you're talking about. In your original post you only mentioned the MSP430FR6889. Are you using both devices with the same code and hardware setup?

    You should implement the changes I have suggested before we go any further. The idea that the device isn't entering LPM3 is only a theory. I don't have a full view of the code or how it operates. I also don't know if there are any peripherals using SMCLK. This is all specific to how your customer has their code setup and they need to ensure that no peripheral is requesting SMCLK from LPM3. 

    Again, its also very important that any unused GPIO are set to output low. This is most likely where the majority of the extra current consumption is coming from. 

    Best regards, 

    Caleb Overbay

  • In reply to Caleb Overbay:

    Here is the code and scheme. 

  • In reply to artem dmitriev5:

    Hi Artem,

    Did the changes made to the code have any affect on the power consumption?

    If you're still having trouble, I recommend loading the example linked below and measuring the current. This example shows how to achieve the lowest power consumption in LPM3 when using the MSP430FR6889:
    dev.ti.com/.../

    Best regards,
    Caleb Overbay

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