Production Arduboy Schematic


(Kevin) #1

Here is the Final Arduboy Schematic in it’s entirety! Fully updated and includes all support circuits!


Battery voltage and internal temperature reading together
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(Josh Goebel) #2

Please clarify:

  • which buttons are which
  • where is CS for OLED
  • where is RGB… is it 9-11?

I think everything else is clear.


(Kevin) #3

A0: UP
A1: RIGHT
A2: LEFT
A3 DOWN
D7: A-BUTTON (Left most round button)
D8: B-BUTTON (Right most round button)

The RGB is on 9,10,11 will update on which is which :wink:


(Josh Goebel) #4

You removed DC I think.


(Scott) #5

It looks like you decided not to put a capacitor on AREF, as I had suggested. To bad :disappointed:

You should consider releasing the schematics for the DevKit as well, since the Tindie site has said for a very long time (emphasis mine):

We still owe you documentation, schematics, board files, drivers… everything you need to fully realize the Arudboy game system. Please pardon our construction as we work to quickly fill these gaps!


(Kevin) #6

All the pins have test pads so you can fairly easily add any components you like. They are under the battery unfortunately due to layout constraints but if you’re adding these kinds of functions it shouldn’t stop you.

For sure, we did release the original schematic and board file for the prototype in the first youtube video. The dev kit isn’t much different but sure I will post it! :smile:


SOLVED: My Arduboy Devkit no longer works on battery power
(Scott) #7

Sure, skilled people can add a capacitor. I could probably do it even without pads. But, If it turns out we are able to do battery level monitoring using the ADC, and add functions for it in the Arduboy library, shipping with an AREF capacitor installed may have improved this capability for everyone.


(Kevin) #8

The number of people who can’t add a capacitor but want to have fine precision on their ADC readouts on the arduboy is probably so close to 0 it might as well be. But that’s why we are proud to introduce Arduboy Plus! It’s got all the features we intentionally left out of our first product in order to force obsolescence!


(Scott) #9

OK, I guess you must have considered my request and decided that you couldn’t afford the fraction of a cent that it would have cost to add it. :wink:


(Kevin) #10

Its not a cost issue but complexity/footprint/aesthetics issue.

The positive thing to look at here, is in the future I do actually want to break pinouts to external connectors so at that point it actually makes a ton of sense to put the component there. And if anything thats the lesson is to make sure its easier for people to do more things with it that I haven’t planned. So in that regard, yeah it’s a little closed and limited on the I/O right now, but thats just to make it more simple and easier to produce for now.

I do always appreciate the input but I’m also balancing a lot of different issues so it’s never personal the decisions I make with the product. As illustrated in the image above I’m just trying to have a good time and would love to add all sorts of cool features in the future.

SD card is next, then maybe IR. Stay tuned!


(Josh Goebel) #11

We can do monitoring of battery voltage already. What does capacitor do, just smooth the reading? We can do that easily in software, can’t we?


(Josh Goebel) #12

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.


(Scott) #13

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.


(Scott) #14

This discussion should probably continue here.


(Josh Goebel) #15

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.


(Scott) #16

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.


(Josh Goebel) #17

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:
http://community.arduboy.com/t/battery-power-level/141/25


(Kevin) #18

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.


(Scott) #19

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.


(Josh Goebel) #20

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