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Power saving methods

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  • Power saving methods

    To a battery powered logger, the power consumption of micro-DRIVE is very high. Here are the measurements:
    Power supply: 3.6V battery
    41.3mA : with leds, 2G SD card, idle
    21.06mA: with leds, 2G SD card, Reset pin to Ground
    20.94mA: with leds, no SD card, idle
    5.27mA: with leds, no SD card, Reset pin to Ground.

    You can see, the power consumption is too high even we put the device in Reset mode. The battery can only last a few days.

    So it seems the best way is to power off the device when not used, but the problem is, from data sheet, the uDrive needs 500ms delay after power up.
    Let's say we have 500 bytes data per second to be loggered, communcation time is little compare to teh 500ms delay.

    Is it possible to reduce the dealy time safely? ie. by changing firmware of uDrive.


  • #2

    How high is too high?

    I think you need to rethink your power supply.

    Your own figures show half the power is going in the SD card, at Idle.

    They draw more when writing.

    SD cards can take take up to 200ms to initialize after power up, not something you want to wait for too often in a data logging application. Powering down will only be effective when its for a reasonable amount of time, say at least minutes.

    These devices have been used in forehead mounted dataloggers for medical applications that run for 8 hourse at a time.


    • #3

      Good point.
      I have 12K spare RAM can be used to buffer the data. when readay, turn on the uDrive, dump all the data and then power it off.