Beginner here. Designed a PC Arcade Controller, trying to figure out how to make it work.

Question

Over the past month or so I've been working on a design for my ideal PC game controller and I'm getting closer to figuring it all out.. And I was wondering if I could run it by the experts here for some help in understanding it all.

Here is the latest version of my design!

It started as my ideal handheld controller and evolved into an arcade stick. The stick I plan to build has two analog sticks; the leftmost analog stick being Ultimarc's Ultrastik 360 (or U360) and the rightmost being a thumbstick. Also on my design are 12 pushbuttons.

So I've been doing a lot of searching and learning about interfaces and such, but I still feel very in the dark. At this point, I believe it's a Teensy board that I'll need in order to convert these signals to digital so my PC can recognize my arcade controller as a HID. So as far as I understand, the voltage of the Interface I use will need to support the highest voltage of any of my switches, right? The U360 has it's own interface that you can hook to buttons and plug and play, but it only supports eight buttons, and my project incorporates 12 plus an additional analog stick. The U360 can also work in output mode, with 2 of it's eight pins outputting raw analog signal. Also note the stick can output digital 100% signals, but that is not what I want to use. I need the analog signals.

Here's the info on the U360: http://www.ultimarc.com/ultrastik_inst.html

So it shows the pin for powering the U360 is 5V.

Sorry for getting off topic a bit, but it says on the raw analog signals "not used at present".. Does this mean I wouldn't be able to use it? I contacted Andy at Ultimarc and he said it can output raw analog, but he seemed to want me to also buy his I-PAC for my extra buttons, which doesn't support analog, and just make my project act as two separate devices: one for the ultrastick and one for the buttons. That still doesn't let me use my extra analog stick and is too... messy for what I want. I want it to be clean and simple.

Anyway, as far as I can understand, I'll need a Teensy board that can power 5V, connect the two raw analog pins of the U360 to the Teensy's analog inputs and it should work fine, right?

Here is the analog stick from Adafruit I plan to pair with it: https://www.adafruit.com/product/512 "Usable with any voltage up to 5V, 2 analog outputs. 1 milliamp draw when used with 5V"

So the two analog sticks would take up four analog pins on a board, right? Then all that's left are the buttons which I can't find the voltage for.. it doesn't say on any of the sites for ordering them. I guess that's not something you have to worry about?

With all this information, if you notice something I'm missing, please let me know.

I guess the main questions I'm asking are: is this going to work with this U360 analog stick wired to a Teensy board, and which board should I buy for this project?

Thank you so much for your time.

jeremy.f.medlin · Answer

Maybe this will help. Arduino is on the left. Each one of those lines represents a wire going somewhere. That +5V which is your power rail will connect to one side of your switch. Then an input pin wire will run from an Arduino pin to the switch in series with a 50K Ohm pull-up resistor. Also that little tail coming off the right bottom of the switch means its connected to ground. If you can see, that means that the 5V power line is connected directly to an input pin THROUGH your switch AND the 50K ohm resistor. This means that when your button is not pressed, the Arduino will "see" the button at 5V but as soon as you press the button the power line will be connected to your ground instead of your input pin and the voltage will drop to 0. Arduino will then see that 0V as a sign the button has been pressed.

I hope this drawing isnt confusing, I only actually filled in how Button 1 will work, but the rest of the buttons will be wired and will work the exact same way. As for the joysticks, they will be a bit different so I figured we'll wait on those.

Sean_Miller · Answer

Good discussion. Your thumbstick is probably just two mechanically driven potentiometers that center on Vcc/2. So, not counting power and ground, you will consume two pins per stick.

Get you the prototyping rig (bread board, jumper (DuPont) cables, your switches/thumbsticks, and an Arduino) rocking and rolling and we'll go from there. Once you achieve that, you might want to build an R2D2 instead.

-Sean

beacon_dave · Answer

This drawing isn't right.

A pull-up resistor input circuit looks like this:

https://learn.sparkfun.com/tutorials/pull-up-resistors/what-is-a-pull-up-resistor

There are pull-up resistors built into the Arduino MCU which could also be enabled in code.

beacon_dave · Answer

You need one pull-up resistor per digital input. There are pull-ups/downs built into the MCU which can be enabled in code. You don't need the pull-up resistors on the analogue inputs.

Perhaps take a few minutes to look at these tutorials:

Tutorial 02 for Arduino: Buttons, PWM, and Functions

Tutorial 04 for Arduino: Analog Inputs

jeremy.f.medlin · Answer

Ah okay! Yep, definitely a way to get the joystick info. Hall effect sensors use voltage to determine direction, so you would read the voltage at the pins in order to find the direction and distance the joystick was pushed. Still should be fine using that with Arduino.

The tricky bit will be once you prototype your board with the hardware, is figuring out how to handle the joystick information in the Arduino coding.

I agree with Sean that you should go ahead and build the prototype because once everything is hooked up, the coding section is a whole other animal. Good idea to build it and get excited for it, then we'll tackle the software side

jeremy.f.medlin · Answer

Each button gets its own 5V line with 50K resistor. The article might be a little dense on why you use pull-up resistors but think about it this way.

Imagine each pin is "listening for a voltage." "Quiet" is 0V and your cell phone ringing is "5V." It's easy to hear a beep when you are in a quiet environment, but as soon as you try to hear that beep in New York City, all of a sudden all those noises interfere with you hearing that beep, or you might hear other beeps that you think are your cell phone, when really it's another person's cell phone.

Now imagine that all that noise from the city is all the random electrical fields that happen in your environment around your Arduino. Even though you can't feel it, there are fields surrounding you all the time. If you left a pin ungrounded or without using pull-up resistors that is called "floating" a pin and any currents that happen around your device might induce voltages that give the impression to your Arduino that there is a button being pressed, but really it's just electrical noise from another device causing that voltage.

The pull-up resistor allows the line to ALWAYS be at 5V effectively drowning out all other electrical noise so you never have the environment causing voltage readings that confuse your Arduino. So why not connect the 5V line directly to the switch and then to the Arduino input pin you might ask?

Well heres an easy equation for you. I=V\R

Current (in Amps) equals voltage (in Volts) divided by resistance (in Ohms).

If you have a 5V line with hardly any resistance, then you will see an amount of current flowing through that pin equal to the amount of current your power supply can produce. Not good seeing as your Arduino can only handle about 40mA per pin.

Instead we put a 50,000 (50K) Ohm resistor to allow the voltage to remain 5V, but resist current flow to keep the amount of current flowing through our pin to a safe level. Lets rework our equation.

Current(to our Arduino pin) = 5V (from our power rail) divided by 50,000 (our pull-up resistor amount)

Current =0.001 mA

MUCH better! This allows the pin to stay "high" at 5V, but only pass 0.001 mA of current. The less current we pass through our resistor, the less heat we generate.

Then when we press the button, we are allowing the current to flow to ground rather than flow to the input pin which the Arduino then "sees" as 0V (because there is no more connection). By having the pull-up resistor on the 5V line to the switch, it also limits the amount of current flowing to ground since the 50K resistor is in series with ground.

beacon_dave · Answer

the internal pull-up works the same as an external pull-up. it's just located inside the MCU device as opposed to externally. your diagram is correct. if you want, you can draw the pull-up resistor inside the UNO between the input and the internal +5v supply. e.g.: http://digitalmedia.risd.edu/pbadger/physcomp/uploads/Devices/MomentaryPullup2.png

Sean_Miller · Answer

I love your energy and I know you are going to pull this off. My son and I made a controller and wireless receiver to control our R2D2. It entailed making our own Printed Circuit Boards. It was a long journey (see video ). If you pull this off, you can build anything. I'd first point that energy to make a prototyping rig. You need a bread board, jumper (DuPont) cables, your switches/thumbsticks, and an Arduino. Then proceed as follows: Get the Arduino blink example to work. Get the Arduino to output your thumbstick position Get the Arduino to output the position of a switch Get the Arduino to output the position of every switch using shift registers. After that, then we'll talk what's the best embedded microcontroller. It may be the Teensy. It could be an Arduino pro mini. It could be a custom circuit board you make that has their open source designs built in minus the pins you don't need. See ya', Sean

jeremy.f.medlin · Answer

Depends on what you want to accomplish. -Choose the Arduino that has the number of input/output pins that you want. Looking at my Uno it uses pin 2 through pin 13 without any tweaking. That means you have 12 pins available to sense if a button is being pressed. -Per joystick it will need at least 4 pins on the arduino, and then of course each button you want will also need a pin. -Unless you are using parts I'm not familiar with, then it looks like you'll need 20 pins. 4 per joystick and then 12 for the pushbuttons. Again, off the top of my head it seems like you'd need an Arduino with more pins available for inputs. Maybe the Arduino MEGA 2560? It has 54 pins, more than enough for your uses. Also if you continue enjoying working with Arduino boards then you will never find a project you can't accomplish with 54 input pins.

beacon_dave · Answer

Get an Arduino Mega 2560 and you have 54 digital IO pins to play with... Perhaps connect your joystick to a power supply via a multimeter and see just how much current it draws.

Beginner here. Designed a PC Arcade Controller, trying to figure out how to make it work.

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