Sanro - Arduino

（このREADME.mdは日本語訳版があります、README_JP.mdをご覧ください、訳は完璧には程遠いですが）
Hardware program of the game Taiko Sanro.

What is This Program

Music game fans from East Asia countries are most probable to know a famous game called Taiko No Tatsujin (太鼓の達人), developed by Bandai Namco Entertainment.

This open-source program aims to help you develop your own hardware taiko at home, just like how you play taiko in arcade halls.

This program is for personal and non-commercial use only. You may design your own taiko and have fun, but you may NOT distribute your product to the public.

Features

• Full support for the PC game Taiko-san Jiro (太鼓さん次郎). Actually, any app/game/emulator using keyboards as input is supported.
• Force-sensitive. I am also developing a new open-source game called Taiko Sanro that can support this feature.
• Supports dense inputs such as rolling.

In one word, your taiko will perform exactly the same as the arcade version if you configure the program well enough! :D

Prerequisites

Because this is a DIY project, you should have some basic electronic engineering knowledge about connecting microprocessors with jumper wires on a breadboard. Soldering techniques, however, are NOT required.

Getting Started

It might take you a few days to assembly and configure your own taiko device. The microprocessor chips are cheap, though, you can buy them from wherever you want.

Preparation

Almost all of these things have alternatives, now I will show you what I used:

• Arduino Micro module x 1
• KEYES K-036 microphone module x 4
• Breadboard x 1
• A few jumper wires
• Micro USB cable x 1
• Arduino IDE

And miscellaneous stuffs like:

• Thick wood plank x 4, best to be shaped like this
• Foamed plastics to connect and fixate the wood
• Superglue
• Other electronical tools like screw drivers and multimeters, etc.

A few things to note:

1. Any Arduino modules with ATmega32u4 chips or Due and Zero boards are supported. Arduino Micro is the cheapest one, though.
2. Using a breadboard is a low-cost option, but it is not the best/stablest choice. There is a PCB blueprint that allows you to print the integrated board and solder up. For details, please see "Making the PCB" part below.
3. You can also design and build your own microphones modules, just make sure you know how to connect them to your Arduino module.
4. Thick, solid, dense and heavy wood is the best choice, while plywood, particleboard and medium-density fiberboard (MDF) are fragile at their edges and can be easily damaged. For better experience, you should cut the planks with the shapes shown in the picture. If you don't have the cutting tools and want it easier, just prepare 4 planks.

Connecting the Parts

The scheme is quite simple. You don't even need any extra resistors or capacitors. All you need are jumper wires.

Each microphone module has 4 pins, and we only need 3 of them (A0, +, and G). Connect their A0 outputs to Arduino Micro's A0~A3 inputs, then connect their + pins together with module's 5V pin, then the G pins together to the ground. Use the following picture if you have any problems.

(Picture to be uploaded)

(Optional) Making the PCB

To make the PCB, you can either DIY or ask local PCB manufacturer for help. If you choose DIY, you should prepare a few more things, including:

• 2.2 x 1.6 inches Empty PCB x 1
• Thermal transfer paper x 1
• Laser printer x 1
• Standard 4-pin header x 4
• Thermal transfer machine (or clothes iron)
• Etchant
• Soldering tools

Detailed process to make the PCB is totally off-topic, and you may need this video to help you. I have included the required printable board file sanro.eps in the Eagle/sanro-arduino folder. You can also download the scheme and board files and edit them by yourself with the Eagle Software.

Uploading the Program to the Board

1. Download and install Arduino IDE.
2. Create a folder and put the source files (sanro.ino and cache.h) into it.
3. Connect your Arduino Micro to your computer with a USB cable. The driver installation should be automatic, but if you have any questions about it, check this official guide.
4. Open the sanro project in Arduino IDE.
5. Select "Board" - "Arduino/Genuino Micro" from the menu.
6. Compile and upload the program.

Configuration

WARNING: Because of the deviations between the microphones and the installation of the planks, you will spend much time adjusting the hardware and the parameters in the program. Be patient, there are lots of tries-and-errors up ahead.

Hardware

Literally there is only 2 things you need to do:

1. Glue each microphone to the wood plank
2. Fixate the wood planks onto the foamed plastics

However, the problem is how you do them. There are some major criteria when doing this job:

• Attach the microphone to the plank as close/tight as possible
• Seal the microphone to isolate it from outside noises
• Don't let the planks contact each other

To accomplish them, you can remove the filter cover of the microphone receiver, then attach the receiver face (the microphones are usually cylindrical, like the ones that I used in this project) tightly to the surface of the plank, and seal it with superglue. In this way, the soundwave from the plank can be directly transmitted to the microphone, loud and clear. Also, noises and soundwave from nearby planks can be reduced to the minimum.

Also, please note that there is a potentiometer on the KEYES module, which is used to set the quiescent operating point (Q-point) of the microphone. Although I have implemented algorithms to eliminate the bias caused by unequal Q-point of each microphone, it is better to adjust the potentiometer manually and keep the Q-points at approximately the same level. To do this, you may need to contact your microphone provider.

Parameters in the Program

All you need to change is the LIGHT_THRES and the HEAVY_THRES, according to your microphone configuration.

The codes are short and self-explanatory, and if you need help understanding them, please refer to the "About the Algorithm" part.

(To be completed)

About the Algorithm

The algorithm in the program is simple, and there are still much more to be optimized. All pull requests are welcomed!

In short, the signal processing job can be divided into 4 calculating steps after acquiring the samples from the analog inputs:

1. Calculate the derivative
2. Calculate the power of the waveform
3. Calculate the convolution of the power
4. Find the peak of the power convolution and compare it with the thresholds to see if there is a light or heavy hit

This picture shows the algorithm in a clearer way:

(Picture to be uploaded)

Step 1 is to elinimate the difference of Q-point, which makes it easier and more accurate to calculate the power of the waveform.

Step 2, calculating the power of the waveform, can also enhance the signal to noise ratio (SNR), which can further eliminate the noises. LIGHT_THRES is also used here to cut the low-power noises out.

Step 3 is to "polish" the power curve to make it more like a sequence of hit pulses, which makes it easier to find the power peak.

For Arduino microprocessors, the executing time for each loop is not stable - the processor always executes the instructions as fast as it can. Onece the loop ends, it immediately starts the next loop. This is extremely bad for sampling sounds. Therefore, the program implements a simple sampling frequency control mechanism to restrict the sampling frequency to no more than 1,000Hz.