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We need low power consumption (1nA - 1uA) while the circuit is closed, and then wake the microcontroller when the circuit is opened.

A the moment the design includes a custom metal switch which will remain closed in its normal, resting state, which we require have very low power. It will open, and that is when our microcontroller needs to be activated.

enter image description here

Adam Davis
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Vjeran Magister Ludi
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    No one will hate you for being a noob, we were all noobs once. But you need to give us more information to be able to help you. You can draw a schematic diagram of your circuit using the editor in the answer panel, this will help us understand you problem better. Also, what do you mean by next to no power consumption? 1mA, 1uA, 1nA? An obvious question for you is why you cannot use a button / switch which works the other way around: ie use a normally open switch instead of a normally closed switch,etc. – Steve G Feb 23 '16 at 10:45
  • Sounds like you just need to connect the button to an interrupt input, with appropriate pull up or pull down. Use 'sleep' mode on your processor, CPU will wake on interrupt. – Icy Feb 23 '16 at 11:14
  • i guess 1uA would be acceptable i 1nA would be even better. I cannot use a button/switch because device because it takes to much space, and it doesnt fit nicely into design. Basically what i have is some metal which when pressed could open circle and when not pressed could close circuit but as the only electrical enginner between us said he could check on microcontroller is it open or closed but it would spend a lot of electricity. i will ask him to put some schematics here tomorrow – Vjeran Magister Ludi Feb 23 '16 at 11:19
  • @icy atm we are doing it with button but it uses more space than needed and it aint reliable thanks to device construction, ayway we want to sortof create our own button – Vjeran Magister Ludi Feb 23 '16 at 11:22
  • @SteveG any advice on lowering electricity? – Vjeran Magister Ludi Feb 23 '16 at 11:25
  • Button / switch / metal contact - same thing. Should still work with wake on interrupt on CPU - use a capacitor across contact to de-bounce, and eliminate fake triggers. – Icy Feb 23 '16 at 11:27
  • @Icy it works but it spends a lot of electricity because contact is always on, right? if not why not? – Vjeran Magister Ludi Feb 23 '16 at 11:30
  • So you are looking to turn on the microprocessor circuit when the button is open, rather than read the buttons state? – Icy Feb 23 '16 at 11:36
  • Why will it use a lot of power? You can arrange it so that pressing the button closes the circuit instead if it is the closed condition that uses a lot of power. I would be better if you explain more about the project, what the button must achieve and under what condition the power drain is important. Then we can give better advice. – user1582568 Feb 23 '16 at 11:46
  • This question has now been closed because you haven't clearly said what you want. I also edited out all the stupid time-wasting and annoying fluff you put at the beginning of your question. Don't get used to others fixing your mess for you. I did this only as a example of how lots of content-free words could be deleted but the question still be the same. We don't care whether you're noob or not. All questions get judged the same, so respect our time by getting to the point. – Olin Lathrop Feb 23 '16 at 12:23
  • dude i was just drawing the pic. why so harsh? – Vjeran Magister Ludi Feb 23 '16 at 12:25
  • http://postimg.org/image/gtetjpo05/ – Vjeran Magister Ludi Feb 23 '16 at 12:27
  • the microcontroller is nrf51822 actually it is wt-51822 chinesee nrf51822 with antena solution... what kind of info u need – Vjeran Magister Ludi Feb 23 '16 at 12:28
  • @OlinLathrop can you check my comments? went for a smoke outside... – Vjeran Magister Ludi Feb 23 '16 at 12:30
  • @OlinLathrop yeah it makes no difference wheter u are noob or not right? explanation is the same if you are explaning to noob or pro right. Well lets try example to explaning a child which is noob how to do complex math lets say for him its multiplication... he would get it straight out right and it would be the same as to person who knows how to do 3+3+3. And a child who doesnt even know how to do 1+1, You are actually being annoying stupid time-wasting person while i am trying to have conversation with other people you are interfering – Vjeran Magister Ludi Feb 23 '16 at 12:38
  • What you have drawn is a "normally closed" pushbutton (NC). Sometimes switches come with contacts for both: NO (normally open) and NC (normally closed). – Tut Feb 23 '16 at 12:59
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    Since you're making a custom switch anyway, you should consider redesigning the switch: http://i.stack.imgur.com/kob5P.png – Adam Davis Feb 23 '16 at 13:07
  • @AdamDavis thats simply genious :) – Vjeran Magister Ludi Feb 23 '16 at 13:08
  • See also: http://electronics.stackexchange.com/q/219303/25328 – Tut Feb 25 '16 at 13:14

1 Answers1

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How about something like this?

schematic

simulate this circuit – Schematic created using CircuitLab

When switch is normally closed darlington will be off, and the micro will be un-powered. When switch is opened, the bias current through the darlington will turn micro on.

Will need careful choice of darlington and R1 to minimise power consumption.

Icy
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