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CC2541 power consumption

zz zhang
Intellectual 330 points
Other Parts Discussed in Thread: CC2540, CC2541

Hi,

    I have designed my project by changing the Keyfobdemo project. And I use the CC2540 for my project.

    Now, I change CC2540 to CC2541 for reducing power consumption (By comparing two chips's datasheet, CC2541 has better power consumption) .

    After I test the current of CC2541. I found it's current is larger than CC2540 (Increases about 20%).

   I don't know why. May I config my projcet with something?  Sorry for my poor English.

  • 0
    Guru 31280 points

    Hi,

    I'm not familiar with BLE stack internals, however, from what I know cc2540 and cc2541 are

    identical except one part, cc2540 comes with USB where in CC2541 the USB part replaced

    by I2C module.

    So may be in BLE stack the I2C module isn't powered down properly?

    I'm suggesting to you to look for solution in this direction.

  • 0 in reply to Igor Sherer
    Intellectual 330 points

    Hi, Thank your firstly.

        I have read cofiguration of I2C moudle from CC2541 SoC user's guide. The register for cofiguring the I2C moudle show as follow:

    And I have found that there is no code to cofig the I2CCFG register in my project. So the I2C moudle is disable default.

    Is there any other wrong with my project or hardware?  Thanks.

  • 0 in reply to zz zhang
    Guru 31280 points

    Hi,
     

    Add I2CCFG &= ~0x40; to the init function in the application, you know, just in case.

    You know, when I posted my first answer, I have made some conclusions without

    asking you for details. Do you mind elaborate a bit more about your project:

    • As I understand the PCB is your custom PCB that is entirely made according
      to reference design (i.e KeyFob reference design). Are there any changes of
      your own?
    • What are the changes in the FW?
    • You said that measured current is higher by 20% from the measurement you
      made with CC2540, what are the numbers you are talking about?
    • How exactly you are measuring the current consumption, what is the set up? 


    Usually excessive current drawn from GPIOs that have wrong configuration, also

    make sure you are powering down all the peripheral ICs.

     

  • 0 in reply to Igor Sherer
    Intellectual 330 points

    Hi, Thank you very much for your careful reply.

    I have found the problem. I use the CC2540 evaluation module from TI. I found the SCL(PIN2) and the SDA(PIN3) were connect to ground.

    I change them to NC, the current drawn rightly.

    But there is a question troubles me. The I2C moudle has been disabled, the current still drawn from SCL and SDA, why?

  • 0 in reply to zz zhang
    Guru 31280 points

    Hi,


    zz zhang said:
    I use the CC2540 evaluation module from TI. I found the SCL(PIN2) and the SDA(PIN3) were connect to ground.

    Are you sure? CC2540 has no I2C module, the CC2541 has it.
     

    zz zhang said:
    The I2C moudle has been disabled, the current still drawn from SCL and SDA, why?

    Well, the cc253x/4x User's Guide states that disabling I2C module won't reset module's configurations. So the SDA

    and SCL pins were probably configured as inputs with pull up, which means you got additional current draw of

    2*(~3V/20K) = ~300uA?

    One thing I don't understand either, in BLE stack there is no header for CC2541 device, so all the I2C can't be even

    accessed (may be it can be accessed through USB registers that have the same addresses, somewhat risky, I'll

    have to post a question regarding this issue).

  • 0 in reply to Igor Sherer
    Intellectual 330 points

    Hi,

    Firstly, I am sure CC2540 has no I2C module. I mean I change the CC2540 chip to CC2541 chip on the CC2540 evaluation module PCB.

    Sorry for my no clear description in the previous post.

    Secondly, Thank you for your answer.

  • 0 in reply to zz zhang
    Guru 31280 points

    You are welcome :)

    By the way, can you confirm that the measured current draw you've seen on your custom board with CC2541,

    was by 300uA higher compared to CC2540 device?

  • 0 in reply to Igor Sherer
    Intellectual 330 points

    Hi,

         The current is about 260uA higher compared to CC2540 device. But my power supply is 2.7V.

  • 0 in reply to zz zhang
    Guru 31280 points

    Ok, thank you for the info (the Pull-up resistors are typically 20KOhm, means that in real life it can be less)

  • 0 in reply to Igor Sherer
    Prodigy 230 points

    Hi Igor,

    I am facing the same problem, I use simpleBLEBroadcaster as the base.

    Then HAL_LCD=FALSE, and not start advertising. 

    compare with cc2540, the cc2541 is ~500uA higher.

    If I disable the i2c, it will lower ~200uA. but still have ~300uA higher.

    Is there anything I missed ? I am using CC2540EM and CC2541EM.

    Thank you.

    Leo

  • 0 in reply to leo devel
    TI__Guru** 106705 points

    Hi Leo,

    If pins 2 and 3 are connected to ground you must make sure to disable the I2C pull-ups. These are not disabled by turning off the I2C-module.

    Cheers,
    Fredrik

  • 0 in reply to Fredrik K
    Prodigy 230 points

    Hi Fredrik,

    Thank you for your support.

    Do you means I2CWC=0x83 ?

    I am using TI's CC2540EM and CC2541EM to do the test, The PIN 2 and 3 are float.

    and I use the same source for both EM, actually after the reboot, it go to PM mode.

    NO advertising, and Power Saving is enable,

    but the current consumption have big different, CC2541EM is much higher CC2540EM.

    Do you any idea ?

    Thank you.

    Leo