My First Projekt - Got some Questions about my Circuit

Recently i discovered Arduino for myself, since that i had to learn a lot about electronics, because i didn’t knew a thing about it before. For my first Project i’m finally done with the planning. But due to the mentioned reasons i’m not quite sure if i’ve done everything right with the circuit. So i thougt it would be better if someone who’s got some experience in this topic would take a look at it, before i actually gonna build it. Also I’ve got some specific Questions.
But first, about the Project:
In the Board-game Terraforming Mars you’ve got 6 Different Resources, and for every Resource there is a round based Income. The resources are counted with little blocks wich represent different values, but the rounds aren’t that long in this game so you spend a lot of time with taking your resources every round. That’s getting quite annoying if you play this game frequently, so i decided to build a Resource counter wich calculates the Resources itself, if the “Next Round” - Button is pressed.

Every Player will have a Tablet like in the upper part of the picture, and all these tablets are connected to the “Counter”, wich provides power supply and contains the “Next Round” Button, to give every tablet the signal to calculate the resources if it is pressed.
On the Tablets each Resource is represented by 2 7-Segment Displays, one for the Income, one for the current amount. To the Right there’s a Display, a Keypad and 12 seperate Buttons to add or remove Income/Resources.
The schematic i’ve made for the circut of the Tablet is in The Attachments.
Every Tablet is controlled by an Arduino Nano. The SER, VDC and GND Wire will be connected to the Round-Counter. The Keypad and the 12 Buttons take 7 Pins each (if i Multiplex the 12 buttons it should work with 7 pins, right?), the Display is controlled via SPI and takes 5 Pins in total.
For multiplexing the 7-Segment Displays i choose to use HT16K33, on the Adafruit-Breakout Board with all the needed resistors etc. already on it, and the wiring for setting it’s I2C Adress. I want to multiplex 12 Digits (4 Diplays) with one IC, the Column with 8 pins for the 7 segments and the Decimal Point, and 12 of the Row pins, each for one Digit. In total i’ll use 3 HT16K33 per Tablet, and controll them in Series with I2C.
So now, about my Questions:
1.In the Round-Counter I plan to use an Arduino Mega2560, so i can connect up to 4 Tablets with a Serial Connection to it. I want the connected Arduinos to communicate in both Ways together, is this possible in the planned Set-up with a Serial Connection?
2:My Supply Voltage is 7,4V, and the HT16K33 needs 5V. I plan to use a voltage converter (like this: for them in the place where’s a resistor in the schematic right now. Will that work?
3. Is the wiring for the I2C communication from the HT’s in Series allright that way?
4. For Power supply i want to use 2 18650 LiPo’s in Series. But i’m quite unsure about charging them correct… I thougt about using a Protection circuit like this:
and charge them with Micro USB(With a normal 5V/1-2A Adaptor). Is there a simple and safe way to regulate the charging Voltage and cut the power supply off, before overcharging the Li-Po’s or damaging the protection circuit?
So that’s it for now, i appreciate every Help, Thanks!

Tm Table_Final.pdf (76.7 KB)

Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.,148850.0.html .

Thanks... Tom... :slight_smile:

Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.,148850.0.html .

Thanks… Tom… :slight_smile:

Thank you. Yes, sorry. I did read it through now, hope i did nothing else wrong except the links and the image?


About the HT16K33?

That’s the Description about the Breakout-Board.
I’ve also attached the Datasheet of the IC itself.

ht16K33v110.pdf (1.2 MB)

  1. Yes. But you may want to keep the "zero" serial available for debugging. Make it easy to disconnect that unit and connect it again at the end of development.

  2. What is the current draw of the display? You may be able to power them from the Nano's 5V.

  3. I can't get that picture to display in high resolution on my phone. It looks superficially like you have I2C wired in parallel correctly.

  4. That will probably work. Is this required to be ultra portable? Maybe choose a slightly heavier battery that is safer or choose a packaged battery with integrated BMS.

Thank you for your Answers, Morgan!

  1. Okay, then i wont occupy that serial Pin, for the Beginning i want to build only 2 Tablets anyway, just wanted to know if i have the possilbility to connect up to 4 Tablets sometimes later. Yes, i was thinking about using some plug system wich is easy to handle at the final device. Got some suggestions for a good system, wich keeps a good fit through many cycles?

  2. The 3 HT17K33 shouldn't draw more than 300mA in total, but i wasn't sure if that coul'd be too much for the arduino's Converter over a longer period of time (3-4 Hours). Could that get too hot or are Currents like this easy to handle for the Converter?

  3. I now uploaded the PDF over the Arduino Forum, the Problem was not your Phone, it's the Website, sorry.

  4. No, saving space or Weight ist not required. Thank you for the Suggestion, i kind of only had Li-Pos (or Li-Ion) in Mind, Decided to use just simple AA Ni-MH Accumulators, load them external and insert them, makes Thing's easier for now, and i still can upgrade that later. Guess i've got to use some kind of Voltage Detection in the Device to protect the Accumulators from Depth Discharge?