Main Site Documentation

Battary holder and power


Does the battery holder is good for FEZ Domino?
If so, where to connect it if I use a component shield?
I would prefer to use a battery as little as possible - any suggestion with what battery to use and how to connect it?


You want the smallest battery possible?


Which is the one that you mention and how to connect it to FEZ Domino?
Can you also answer my first questions?


The battery connector I posted will connect to the barrel jack of the FEZ.


Yes it is good for FEZ domino. Connect the red wire (+5v) to Vin and the black (GND) to GND.


Uh, Robert, that’s a 9V battery, it will plug directly into the barrel connector. Putting it to 5V will not end well.


He asked for the battery holder, not a 9v battery?


He’s got a Domino, so he can either pipe 5V into it or 9V. Piping 5V isn’t going to work out so well (5 / 1.5 != int), so his other choice is 9V. It’s not like the Mini’s carrier board or anything.


So connecting 9v won’t cause any damage?
What about coin sell battery (photo is attached) ? Any idea how to connect it?


Chris, Vin is the same as the external power connecter. 4*1,5 would be 6V which is fine.

The coin battery won’t work as far as I know, since it’s only 3V. Correct me if I’m wrong.


Ami, it’s time for you to explain more about what you are trying to do.

With a battery like Chris pointed out earlier, that will allow you to [italic]run [/italic] your Fez without any other power supply.

The battery you show, a “coin” type battery, can be used on a Domino to power the [italic]real time clock[/italic] to maintain the time in the RTC when other power sources are disconnected (when the main processor is not running). It connects to the VBAT connection on Domino. If you want to use that, you will most likely need a holder for it, and then wire the GND to GND on the Fez, then the + into VBAT.


I think you forgot to post battery pack? I thought you were telling him to push the 9V to 5v

EDIT: Ah I see, you forgot to post the link to the pack you were talking about and I was skim reading, as usual.


No I was not, he was asking if the battery pack (of this site) would work. :slight_smile:


Ah, I see. I couldn’t understand him very well then. I didn’t even know we had battery pack! :smiley:


Haha no problem. I did know, because I’m drooling at some parts on the site from time to time, lol :smiley:


What I’m trying to do is a small portable and light MP3 player.
This is why I’m trying to find the smallest power source that is available for FEZ Domino.

From the “Begginers guide to NETFM”, section 9.2 Digital input, pages 37-38:
“Important note: 5V-tolerant doesn’t mean the processor can be powered off 5V. Always
power it with 3.3V. Only the input pins can tolerate 5V on them.”

Now I’m a little confuze. The battery holder in this site is for 6v. Chris suggested 9v connection.
What is the recommended power to use?
I asked about the coin battery as an example. If I’ll find coin battery of 5v for example, it is good for the board and CPU power and more than just for the RT clock? And if so, how to connect it properly.



The FEZ has a regulator, so 9V going into VIN will be regulated down to the 3.3V required to power the chip.


Now we understand a little more about what you’re trying to achieve, we might be able to get a better solution for you. What might also help is knowing what parts do you actually own, and what are you looking to buy?

Remember that a coin battery, at 5v, won’t hold very much capacity, so it will run down very quickly, depending on how much current your circuit draws. The 3v battery like a CR2032 is intended to run for a LONG TIME on a very very very small current draw in a real-time clock circuit, not to be the only power a device gets - I’d discount this as an option at the moment.

You can run a Fez on a single AA or AAA battery if you want. is a good example of a 3v3 circuit, they have a 5v as well. You could feed 3v3 into VIN and that will power your Fez. Depending on what your MP3 decoder/player will run on, that may do.

hope that helps.


I’m using a shield on top of the main board, so I suppose that I need to solder the wires into 3v/5v.
I think that also will try the Barrel Jack Adapter for 9v that Chris suggested.
I that assume both ways are possible?


If you think about it this way, you should be fine.

If I can provide a regulated 5v supply, I can feed it direct into the board, bypassing the regulators.

If I can provide 7v up to 12v, then I can supply that into the regulators on the board, to run the board.

The barrel jack is the latter

In the case of whether you need to solder or what, the answer can be no. If you’re using this MP3 decoder, or if you’re using any shield that continues to be stackable (so it has female headers on the top side) then you can simply jumper a male wire into the female header socket (either into the top shield, or the Fez) - it’s not very permanent though. If you want it “robust” like a portable MP3 player then soldering the wire somehow onto the pad is going to be more permanent and make it more reliable, potentially smaller too.