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How to run my atmega 328 chip from 4 AAA batteries?

Former Member

Hello,

 

Im currently working on my first real noobish project, its a temp/moisture sensor for my brother for his organic garden,

i have all my leds and 330 resitors soldered on, but i need to know waht componets i need to take 4 AAA batteries and power my chip without the Arduino,

everything can fit into the container i want it in (an altoid can) but i need to know what resistors/capactors or regukaters i need ino order to safely run my hardware.

 

also what ways can i use my multimeter so i can measure the volts and amps, so i can calculate how long the batteries would power the device.

I hear alot of great things about the element 14 community and i cant wait to hear what you guys have to say image

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    He's probably trying to run the chip by itself, with out the arduino board.

     

    Thing is that you'll have 6V and you only need 5V or less. To get 5V from 4 batteries you will need a LDO (voltage regulator with low voltage drop), however that's wasteful. A better approach would be to just use 3 batteries, which will give you 4.5V tops and run your chip from that - no regulator required.

     

    That aside, you will need decoupling caps on each VCC input (100nF ceramic caps), maybe an electrolytic cap too (of a few uF) across the rails and that's about it. Make sure you enable brown out detect, so the chip shuts down on under voltage - that way you'll know for sure that it won't start malfunctioning when the batteries run out.

     

    Another thing you might want to do is to increase the value of those resistors a bit. The less current you draw, the more your batteries will last.

     

    To get an idea about how long the batteries will last, you can measure the current consumption of your circuit and divide the mAh rating of the battery by that number. The real number will be smaller, since the voltage also drops as the battery is discharging and it will reach a point where you can't use it anymore, way before the battery is fully discharged. To get a better idea of how long the battery will last with your load, you can check the datasheet of your batteries, where you should find some discharge curves.

  • 0 in reply to jadew

    As an option he could also use the TI Battery Booster pack. Even though it is not plug compatible, it will easily work with an Arduino using jumpers and has nothing specific to an MSP/Launch Pad system. In my review I even had an Arduino talking to it to prove the fact.

    Using a single battery (LIPO) and two buck/boost regulators providing 3v3 and 5v

     

    a neat little package see here http://www.element14.com/community/roadTestReviews/1712

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