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PM2 mode power?

jun wang3
Prodigy 190 points
Other Parts Discussed in Thread: CC2541, CC2540

Hi，

  TI document is under the PM2 mode,working current of the system is 0.9uA. But I measured actually is 1mA.
  Test conditions：

                Minimum system, external 32M crystal, external 32768Hz crystal, and all IO  NC.
 

 Can you tell me,what happened?

         Best regards！

          Thanks！

  • 0
    TI__Genius 10955 points

    With all I/O's not connected, you must make sure to set P1.0 and P1.1 as outputs to get a defined output level (P1DIR |= 0x03). The other I/Os have pull-ups by default and may be left in their reset state.

    You must also measure the current consumption while not in debug mode. But I guess that is already the case if your I/O's are truly not connected.

  • 0 in reply to hec
    Prodigy 190 points

    Hi,

            Moreover,in order to reduce the power consunption under PM2 mode,whether should I set all I/Os pull-ups before entering the PM2 mode?

            Then revert the IO after waking-up from PM2 mode.

             Note:   The CPU is CC2541.

              Best Regards!

              Thanks!

  • 0 in reply to jun wang3
    TI__Genius 10955 points

    It should normally not be necessary to change the I/O state before going to sleep.

    Generally (both in sleep and at other times) you should have all I/O pins at a defined level (VDD or GND). For unconnected pins, this can be achieved by pull-up, pull-down, output high or output low (only the last two are available for P1.0 and P1.1).Pins that drive external devices should be outputs, and while in sleep, at the level that gives minimum output current (e.g., a LED should be off). Pins that are driven externally can be tri-stated if they are driven at all times, otherwise pull-up or pull-down, but configured so that you avoid current flow while in sleep (i.e. pull-down if driven low, pull-up if driven high).

  • 0 in reply to hec
    Intellectual 545 points

    Hi, hec, there is also a question about PM2. How to suspend UART hardware before entering PM2 ? 

    The device uses USART 0 as SPI  mode Alt. 2.  And then  how to resume UART hardware after exiting PM2 ?
    The program environment is BLE stack 1.4, CC2540 , based on SimpleBLEPeripheral project.

    Best regards !

    Key

  • 0 in reply to key dongle
    TI__Genius 10955 points

    The USART hardware will not cause any current consumption while in PM2, and you don't have to do anything. While in PM2, the USART interface will not be operational.

    If you are in SPI slave mode, you need to design the protocol so that the master will not try to transmit while the system is in sleep or while it is coming up from sleep. If you are in SPI master mode, you need to make sure that the SPI transaction is finished before you enter sleep mode, and you should wait for the system to running on the XOSC before you start using the interface after coming up from sleep mode. As far as I know, the sleep controlling part of OSAL will ensure that no task is started until then, so it should be easy to obtain.

  • 0 in reply to hec
    Intellectual 545 points

    Thank you so much for your detailed answer.  It is clear in my mind.  

    key