JOYDAC - The Digital to Analog Converter for Brook PCBs
In 2020 I was commissioned to build a stick that required a lot of extra directional inputs. The stipulation was, they couldn’t be “double stuffed” into the Brook PCB. Meaning, I couldn’t just connect two buttons to the UP screw terminal so there were two UP buttons. They had to use the analog joystick inputs for the Brook PCB. Well, as you know you can’t just connect standard digital buttons (ON/OFF Momentary Switches) to the Analog inputs on a Brook board, it doesn’t work quite that way. In the most basic explanation, the analog stick is basically a pair of potentiometers along both X and Y that alters the voltage on an X and Y output pin. This voltage output tells the controller how much you’ve moved the analog stick along both axis and the result is some sort of movement by your character.
In fighting games, we only care about a full press of a button because there aren’t analog controls governing movement. That would make inputs for moves miserable! So we needed to figure out a way to take a digital button press and turn it into a full UP, full DOWN, full LEFT, or full RIGHT movement of the LEFT ANALOG stick on the Brook PCB. What did I do? A little programming, a little microprocessor circuit board design, and voila…. JOYDAC.
JOYDAC is simply a Joystick Digital to Analog Converter. The buttons for UP/DOWN/LEFT/RIGHT are converted to an analog signal using a microprocessor and some supporting circuitry and sent to the Brook PCB as analog signals.
Connections:
- Along the top of the board, digital buttons are connected via JST PH-2 connections as well as the required 5V and GND connection. You can always tap off of the Brook PCB’s VCC screw terminal. This is normally the 5V bus coming off of the USB cable.
- Along the bottom of the board, this Molex KK connector (2.54mm pitch) has the 3.3 VCC line, GND, and the buttons/axis inputs for the RIGHT and LEFT analog sticks. Connect all of these to the Brook Board. The Right Analog stick and L3/R3 buttons aren’t used by JOYDAC but when the analog stick is connected and enable all of these connections must be made up so that the Brook board doesn’t do anything funky with the sticks. They tend to move around and float a bit. You don’t want that!
FAQs:
- Do you support this board? This article is the extent of it. I just put these out there for people to play around and experiment with. Enjoy!
- Will you make more? Unless there is a huge uptick in folks needing these PCBs, probably not. I’m surprised anyone actually bought them outside of the one customer who had me do their custom stick.
- What’s the programming header for? Programming the microprocessor. Don’t mess with it or you could erase the code and brick your JOYDAC.
- Do you have plans for this? No. Not at the moment.
- Do I need to connect both the 5V and 3.3V VCC lines? Yes. If you don’t this won’t work at all. It needs power from both sources.
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