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MSP432P401R: MSP432 current consumption in LPM3

Aaron Betschart
Prodigy 30 points

Part Number: MSP432P401R

Dear supporters and users

Before I describe my problem I give you some Information, that you might use to answer my question:

- Used HW: MSP-EXP432P401R-Evalboard (The older version with the dark surface)

- SW: C++ Firmware in CCS 6.1.3

My aim is to break the current consumption down to a minimum to save battery-power. So I'm trying to activate LPM3.

In CCS, the Controller seems to enter the LPM, but I measure a current of 1.5 mA upto 2 mA, what is really high when I look at the datasheet. I am using an external power supply unit and pulled out all jumpers (3.3V, 5V, TXD, RXD, LED...).

You can see the relevant parts of my code in the attached files.Lpm.h8156.code.zip

There are two implemented classes: LpmCtrl and Lpm. Lpm enables the low power modes. LpmCtrl controls, which LPM should be activated.

Where is my mistake? Does someone see the problem?

Regards

Aaron

  • 0
    Intellectual 965 points

    I ran into a similar issue and the solution for me to was move the slide switch to "ext debug".  You will need to free run the program since you lose the debugger by doing this.

  • 0 in reply to Dubnet
    TI__Mastermind 41740 points
    Aaron,

    With regards to your code, you also need to terminate any pins that you are not using in order to minimize the power consumption. This is done by register accesses for simplicity and to minimize branching API calls.

    Youll also wnat to make sure you are clocking the device from a low power consumption clock to further minimize the current consumption. Please view the following example, which should help in our tests/implementation.

    dev.ti.com/.../

    Read the Description in the notes of the pcm_go_to_lpm3.c file for more information on the example.
  • 0 in reply to Evan W
    TI__Mastermind 41740 points
    Aaron,

    Also just read you are using a black launchpad. TI recommends that you use the Red LaunchPad (Rev 2.0 and above). The black launchpad contains experimental un-released silicon which is no longer supported. To enable your application with the most up to date software and hardware bug fixes, please use the red version which features Rev C silicon and above.

    www.ti.com/.../msp-exp432p401r
  • 0 in reply to Evan W
    TI__Mastermind 41740 points
    I'm going to close this thread due to innactivity. If you have another question unrelated to the topic above, please post another thread, if you have any more questions related to this, feel free to post here and thread will reopen.
  • 0 in reply to Evan W
    TI__Mastermind 41740 points
    One other comment is to make sure you disconnect the jumpers that connect the XDS debugger that is located on the top half of the board to make sure you aren't loosing any current by powering that.

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