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This article describes a method to extend the battery life: use a low-power controller to switch on the Arduino only when needed. The author states that this method uses considerably less power than using Arduino's sleep mode.

Are there downsides to this approach? Which variant should I build?(The TPS61240 variant seems to use something from Circuits@Home that's not available anymore.) I'd appreciate schematics or links to detailed instructions.

Background: I'm building a sensor device that's in an environment with no mains power supply. The sensor should wake up eg. hourly, read eg. a temperature sensor, possibly send an SMS and then go back to sleep.

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seems a bit overkill to use a microcontroller for that task. –  jippie Apr 6 at 17:46

1 Answer 1

Switching off power to the board only makes sense if you're using a full Arduino. Once you strip the Arduino down to the bare MCU and decoupling capacitors (or start with a basic breakout board instead), disabling unused peripherals and sleeping the CPU has much more of an effect since you no longer need to supply power to an external monitor chip.

Naturally this may involve creating your own board for the MCU. Fortunately Atmel has the basics of that covered.

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Thanks for the answer. Some reasons why I thought that using an external power controller would be more simple: 1) I could use off-the-shelf Arduino board and a GSM shield. The GSM shields need momentarily a lot of current (2A), and I didn't research yet whether it would be easy to completely switch off the GSM shield from Arduino. 2) I'm not sure whether the GSM shields are compatible with OSCCAL and clock_div_4 optimizations. 3) I couldn't easily find what the sleep consumption would be with a stripped down Arduino. Could you help me with these points? –  tuomassalo Apr 7 at 5:19
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A PMOSFET can handle powering down the GSM module completely if required. Clock prescaling can be set to 1 while communicating with the module, and tuning OSCCAL is completely optional. The datasheet for the MCU talks about current usage in the appropriate "Electrical Characteristics" and "Typical Characteristics" section. –  Ignacio Vazquez-Abrams Apr 7 at 5:33
    
There's a good chance the GSM module already has power conserving modes of its own, though perhaps those aren't readily exposed by whatever interface is used. –  Chris Stratton Apr 7 at 16:14

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