I have this circuit circuit diagram and I have to somehow integrate this into a mobile phone cover. So to power it, I was thinking of using a 3.7v 600mAH Li-Po battery. I want to integrate the battery into the cover in such a way that the cover becomes a rechargeable cover.

As pointed out by Marcus Muller, before deciding on certain core factors of the design, it is important that I mention the requirements for this project. So:

  1. I am creating an interactive game and I basically want this circuit to act as an input to the game that will be played on a mobile phone.
  2. The circuit has to fit into a mobile phone cover and the push buttons that you see on the circuit are to be placed on either side of the cover. Both buttons have to be pressed simultaneously to create the required action(s) in the game. I already have this part working.
  3. I am stuck between using Bluetooth or a USB connection from the circuit directly to the phone. If I use bluetooth, then I would like the circuit to be powered by a rechargeable battery pack also housed in the mobile cover. If, however, I decide to go with using USB, then I will power the circuit directly from the phone's own battery.
  4. In terms of how long I would like the battery to last between charges: a similar amount of time that a phone battery lasts (if that's any measure to put things into perspective)
  5. At this point, the power source is my main concern. I know that if I choose to use USB then the ATMEGA328p as is will not suffice, as it has no USB capability.
  6. The main reason that I chose the ATMEGA328p is that I have used it in the past and am familiar with it.
  7. I am not sure what the best solution for this will be; by best I mean the easiest and least complex to implement.

Any assistance will be appreciated.

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    \$\begingroup\$ Point 3., the voltage that the push buttons require, is already a fallacy; buttons don't require a voltage. Be careful when stating requirements – it's all to easy to think "oh, this is a requirement", when it's just actually something you think that's necessary technically (and here, the 5V is pretty certainly wrong). \$\endgroup\$ Dec 3, 2019 at 22:48
  • \$\begingroup\$ @MarcusMüller Oh wow, you're very much correct. I just tested the push buttons using 3.3V and it works just the same (my whole life feels like a lie); all the push-button tutorials I have seen have used 5V so I think that is where the misconception stems from. I tried googling for what the minimum voltage for this push button is but I couldn't really find it in any of the data sheets \$\endgroup\$
    – user19964
    Dec 3, 2019 at 23:24
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    \$\begingroup\$ your still doing engineering backwards! instead of going "hm, I want to achieve this and that; what do I need to do and to use?" you're going "I think I need to use this and that, so let's start with that!" You'll realize that your ATMega is probably useless in both the USB and the bluetooth use case. \$\endgroup\$ Dec 4, 2019 at 8:23
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    \$\begingroup\$ @Marcus Müller I am trying to state what I need and then look for options to fulfill that need, I didn't realize that it was wrong to go about doing it this way :( Also, there are probably better options that the atmega, but in terms of bluetooth, why is it useless? If I use a bluetooth module with the atmega won't it work? I understand that you're trying to cultivate the right thinking in my design process and I do appreciate it; i am just struggling to see why the way I am going about this is so incorrect \$\endgroup\$
    – user19964
    Dec 4, 2019 at 10:50

1 Answer 1


I have this circuit circuit diagram and I have to somehow integrate this into a mobile phone cover.

No, because that'd be bad: placing conductors around the place where your mobile phone has most of its antennas will make the phone work way worse. Don't do that.

So to power it, I was thinking of using a 3.7v 600mAH Li-Po battery

Wow, that's a lot of energy. Your microcontroller should run years off that, if designed appropriately.

I know I will probably need a booster somewhere (to get the voltage from the battery to be 5V)

Clear indication that you should use a different microcontroller: Only very few microcontrollers these days need 5V, and all convert down these 5V to way, way less for their core.

So, dump the gigantic and ancient Atmega for something smaller that can directly run off battery voltage (or lower).

how do I begin going about making this a rechargeable arduino project?

So, considering you've posted a wiring diagram instead of a schematic, and forgot to tell us what this thing actually needs to do:

Start by writing down requirements for the finished system. Only after that decide on the components: I kind of doubt you'd be best served with any Arduino-based platform, but even if you are, I don't see any reason to use the enormous Atmega168.

So, as said, start from specifications. Break down your problem into smaller problems, like finding the right components, drawing a schematic (instead of a breadboard wiring diagram – you can't carry a breadboard around, anyway), coming up with a mechanical drawing that shows what needs to go where, converting the schematic into a layout based on your mechanical constraints, and finally building and testing everything.

Notice that you'll really need to learn how to make PCBs (it's not hard) to make a flat, reliable device (breadboard is not only clunky, it's also terribly unreliable when carried around!).

In any way I turn this, really learning how a schematic abstracts your circuit to its connections, and doesn't "mix" them with the physical layout like your diagram does, is paramount here: I have not even checked your circuitry above for "correctness", because it's a lot of work seeing what things are meant to be when all you see is a wiring diagram, but it's easy when you have a proper schematic.

Baby steps – start small.

  • \$\begingroup\$ Thank you for a very in depth answer. Just to respond: 1. The design brief involves creating an interactive mobile phone cover that can communicate with a game i am developing, so I kind of have to put this into a mobile phone cover. 2. Which microcontroller would be better? The Attiny85 maybe? 3. Yes, much ultimate goal is to develop this onto a PCB, the breadboard is just for prototyping. Okay, I will get started on some of these useful tips. Thank you very much @Marcus Müller \$\endgroup\$
    – user19964
    Dec 3, 2019 at 15:07
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    \$\begingroup\$ re 2.: you're not listening to my advice. Complete requirements first, then you can decide which microcontroller! What you described is totally insufficient to decide which microcontroller. \$\endgroup\$ Dec 3, 2019 at 16:02
  • \$\begingroup\$ okay, I do understand that. By requirements do you mean voltage requirements? Just to clarify @Marcus Müller \$\endgroup\$
    – user19964
    Dec 3, 2019 at 17:11
  • \$\begingroup\$ no. Requirements are all requirements. Like "needs to fit into this and that", "battery life > x hrs", "has three buttons that do this and that", "has an LED at place thisandthat", "reacts to user input by this and that": All the requirements. Voltage is not an original requirement! It's (wrongly, by the way) been induced by you by what you think is necessary, but that should already only have been decided after you've written down what your overall system is required to look like. \$\endgroup\$ Dec 3, 2019 at 17:26
  • \$\begingroup\$ Okay this makes things a lot clearer. Thank you for that. I will edit the question accordingly and hopefully after knowing what my requirements are, I will know better what i am confused about @Marcus Müller \$\endgroup\$
    – user19964
    Dec 3, 2019 at 17:42

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