Production Arduboy Schematic

We should talk, something like a 3-4 wire serial cable and a simple port (or even header - male or female) would be amazing. Then just plug two Arduboys together for 2 player gaming and we can figure out the protocol later…

If you’re lazy you could wire out the serial RX and TX ports or something… other wise we’d have to build our own software SPI, but that’s not the end of the world.

Yes, it’s just to improve noise immunity. From the datasheet (emphasis mine):

AV CC is connected to the ADC through a passive switch. The internal 2.56V reference is generated from the internal bandgap reference (V BG ) through an internal amplifier. In either case, the external AREF pin is directly connected to the ADC, and the reference voltage can be made more immune to noise by connecting a capacitor between the AREF pin and ground.

So it’s just a “nice to have” addition that would have been easy to implement and inexpensive. And for such a small component, I can’t see that board space or aesthetics would have been an issue.

As far as software filtering goes, it depends on how much noise is picked up. The battery readings between charged and discharged will only cover a small portion of the total ADC range, so the more accurate the readings are, the better, for determining charge level, time remaining, etc.

This discussion should probably continue here.

I’m not sure that a capacitor is any more accurate than software smoothing… they are both taking the exactly SAME raw output and filtering it. Now obviously a capacitor has the benefit of being hardware vs software, but I think we can model the exact same behavior in software without much effort. The simplest smoother would start the the initial value (or get two) and then just loop check current vs previous and restrict movement of the artificial value by either a fixed amount of a portion of the actual move. Fixed amount produces the steadiest signal.

I was already playing with this idea just the other night.

I’m not saying that that exactly models a capacitor, only that such a thing would be doable… I don’t know enough of the electronics to do it exactly. Someone who did could probably give you some math though.

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Even if software filtering work as well as a capacitor, it take extra code to do it. That space would be lost to a sketch if it used a battery check function.

No use crying over spilt milk. The fun all comes in seeing how little software builds a great battery sensor… I read the problem with these nice rechargables though is the voltage doesn’t really drop until the end and then it just falls off, so without access to the charging circuitry it’s not really all that useful to just know the raw voltage. We should make a thread of just this topic.

Been there done that:

It is possible to use the bandgap in software to read the system voltage. However in order to be accurate, each unit would need a calibration figure adjusted to it. You can of course run this calibration yourself. But I figure that even with a default value you’d be able to get at least 20% accurate which should be sufficient to give you a 4 segment battery readout or at the very least a low power indication.

I do regret not putting in a battery charging IC that has another leg for a fuel gage, they exist and I basically just got busy/ran out of time/patience with the design for kickstarter. This is almost certainly something that will get added.

Maybe not. The voltage range that the battery covers between full and low is so narrow, compared to the full range of the ADC, that without calibration, the error in some units may be to much to accurately determine a low level.

Without full schematics available, to look at all the components and implementation of the power circuitry, it’s hard to say for sure.

Could do some real life testing across units, but waiting for battery to die testing is boring. :slightly_smiling:

I’ve got my home made unit, and a few other ATmega32u4 based Arduino compatible products that I could test, if code was made available. These all accept external power, so I could use a variable output power supply instead of a battery.

The only problem is that all my devices have a capacitor on AREF, so the readings may be a bit more stable than an actual Arduboy. Other than that, there’s no need for an actual Arduboy if the test program outputs it’s readings to Serial. I can compare the outputted readings to the actual voltage the power supply is providing.

The program is simple:

void setup() {

void loop() {
  int a;

  // Do whatever it takes to read VCC and convert it to volts.
  // This could include multiple sample with filtering/smoothing if it helps.
  a = getVoltage();


Hi all,bit off subject,gambuino bootloader etc works on this,great for uploading games from sd card,just need to recompile the open source bootloader and place arduboy logo instead of gamebuino,sweet,ime gona have a pcb made up of it,watch this space;-)

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Yep we talked about this and we are looking at SD card in the future, excited to see what you come up with!

Any idea what this error is,ime havin g trouble compiling this bootloader?

Could very well need a custom make file or something? Probably better to ask on the gamebuino forums? Or would that create a war? lol… Rodot did pre-order an arduboy. I should probably return the favor!

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Can I have the pattern layout of the circuit of Arduboy 1.0?
Some lands are come off so that I want to find where to peel the regist…

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Agreed, I’ve followed your post here…

It would be extremely helpful for the the actual schematic to be available at this point. Although it’s still a project that’s just finished being Kickstarted, it’s in a lot of hands now. It’s sort of hurting everyone who hacks to not know the layout for sure. I’m pretty interested in seeing your process in getting a bootloader on there @koteitan. If @bateske doesn’t release a schematic or something to help, and you trash your board on accident, I’ll buy you a new one myself :D. Assuming I’m not in the “brokeverse” at the time.

Good stuff, glad you are making some progress.

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He patiently found the problem.
But His Arduboy Pins(SPI parts) is broken.
he used soldering iron.

The physical connection of the SPI is difficult.

I agree @ekem of speech.

…If I was Official Staff and no idea, I would send him a new arduboy :slight_smile:

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The schematic is the top post of this thread! Are they looking for board files? Confused!

@bateske is it possible to get the eagle schematic file (not looking for the board file) ? I’d like to make a few changes for better guidance.


Maybe? Can you write with some more details and I’ll see if I can dig it up. (It’s actually in a backup hard drive by this point)