Low-power modes in microcontrollers: Important for battery powered wearables/implants

edited February 2015 in Everything else
I just came across this: http://www.openhomeautomation.net/arduino-battery/

It's an article talking about how to use atmel's low power modes in Arduino code. I don't know if the Circadia's firmware can be updated while implanted, but in the future versions this should help increase it's battery life.


  • futile on the circadia. While it would enable the firmware to enter deep sleep modes, the hardware is not build to make use of the low power modes. An external low frequency clock crystal would be necessary to wake up from the deep sleep mode. Or some other external wake-up source. But even with that you'd run out of luck cause the circadia has a voltage divider hardwired to the battery, making it an effective bleed resistor with 31kOhm. So it drains more than 100μA during operation (and continues to slowly drain the battery even after dropping below the lower cutoff voltage, but that's another story).
    At least that's what i can tell based on the schematic that was put up by grindhouse wetware.

    So yeah deep power modes are nice, good to see them available in arduino code. Most of the time the battery's self discharge is amongst the biggest "consumers" (unless you have high energy demands like the led's on the circadia).
  • After we finish Northstar, we're planning on revamping Circadia a bit to allow it to make use of the deep sleep modes.  We're even planning on getting off of Arduino-based stuff, both for software efficiency and power efficiency reasons.
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