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Power mode with UART working

Nicolas Brunner
Intellectual 610 points
Other Parts Discussed in Thread: TPS62730

Hello,

What is the lowest power mode that have the UART working ? What is the power consumption of this mode ?

Is it possible to use a low baudrate so the MCU has enough time to wake up from a lower power mode ?

Best regards,

Nicolas

  • 0
    TI__Guru 57865 points

    Hi Nicolas,

    The CC254x must be awake during UART operation so ~8mA. You will get around 6mA if you use a DCDC (TPS62730). You can of course go into sleep between the UART transactions which effectively reduces the average consumption.

    Best Regards

  • 0 in reply to J Lindh
    Expert 1570 points

    Can CC254x be awakened by a pulse on a pin?  Or do I need a different circuit to completely cut power to it?

  • 0 in reply to Sign Bit
    TI__Guru 57865 points

    Hi,

    Yes, as long as the pulse is longer than 20ns. Note that there are two sleep modes which are automatically controlled by the TI BLE stack:

    • PM2: sleep during connection or between scheduled OSAL events etc. Is woken by sleep timer interrupt (or external interrupts)
    • PM3: sleep when there are no scheduled OSAL events (nor connection) . Is woken by external interrupts only
    Best Regards
  • 0 in reply to J Lindh
    Expert 1570 points

    Is that functionality (wake-up on a pulse) available in HostTestRelease in stack 1.3 ?  What pin should I use?

    (I confess I scanned the source code but I'm not familiar with 8051, OSAL, etc).

    When the sensor tag is outside of a session and not advertising, it is sleeping in PM3? If so, maybe I could look at its source code (and adapt it to HostTestRelease), since we wake it up using the side button. Is my assumption correct?

    Reading sections 4.1.4 and 4.6 of the CC254X User's Guide, it appears that the state of the UART preserved in PM3.

  • 0 in reply to Sign Bit
    TI__Guru 57865 points

    Hi,

    Sign Bit said:
    When the sensor tag is outside of a session and not advertising, it is sleeping in PM3? If so, maybe I could look at its source code (and adapt it to HostTestRelease), since we wake it up using the side button. Is my assumption correct?

    Correct, so you should take a look at the Sensor Tag code.

    Best Regards