ArduinoTaikoController/README.md

# ArduinoTaikoController

Sketch for Arduino based taiko game controller circuit

## Software Setup

Install the latest version of Arduino IDE from the official website: [https://www.arduino.cc/en/Main/Software](https://www.arduino.cc/en/Main/Software)

To enable nintendo switch functionality, replace the following files with the ones provided in "setup" folder:

- <your arduino installation path>/hardware/arduino/avr/libraries/HID/src/HID.h
- <your arduino installation path>/hardware/arduino/avr/libraries/HID/src/HID.cpp

Then copy the text in board.txt in "setup" folder and append it to the following file:

- <your arduino installation path>/hardware/arduino/avr/boards.txt

To enable or disable keyboard and Nintendo Switch controller functionality, remove or add two charactors "//" before these two lines in taiko_controller.ino:

```
//#define ENABLE_KEYBOARD
#define ENABLE_NS_JOYSTICK
```

## Circuit Setup

Connect the sensors to the 3.3v pin and the analog pins according to the diagram below:

![](https://i.loli.net/2019/03/07/5c812d28e0978.png)

The mapping of the sensors by default should be:

- Left Rim: A0
- Left Surface: A3
- Right Surface: A1
- Right Rim: A2

To customize the mapping, checkout the [parameter](#parameters-with-suggested-values) section.

For most of the times, pluging the sensors directly into Arduino's pins will work.
If the controller seems to be generating random inputs, you can fix this by plugging some 1MΩ resistors in parallel:

![](https://i.loli.net/2019/03/07/5c812d28e101d.png)

For best performance, the sensors must be piezo sensors (a.k.a. peizo speakers, contact microphones). No guarantee if other types of sensors will simply work, but if analog signals with voltage ranged 0-5V are fed into analog pins, this setup should be good to go.

For further improvements, you can use some diodes to limit the voltage of the piezo sensors, or use a 2.5v power supply, but this won't matter in most cases, at least on my side.

If you can somehow connect a 4x4 matrix keyboard (no pull-up resistors needed) to Arduino's digital pin 0-15, it will work as a controller along with the drum:

![](https://i.loli.net/2019/03/07/5c813dc59e6a0.png)

## Algorithm

This sketch uses a dynamic threshold of sensor levels to trigger inputs. Whenever the sensor level from one sensor is higher than the threshold, a keyboard or Nintendo Switch controller input is generated, then the sensors will be put into a cooldown period. When an input is triggered or during cooldown period, the threshold will be raised to a ratio of current sensor levels, and after that the threshold will gradually decay by ratio, to hopefully be an envolope of the waves of sensor levels.

As the sensors should have biased input voltages, the sensor levels are actually the differential value of the analog value from ```analogRead```.

To deal with four analog inputs, we read the sensor levels one at a time, and only do the triggering mechanisms for this sensor. To compensate the time difference, the sensor level for the current one will be a mix of values from previous read and current read. Also, a non-default non-blocking version of ```analogRead``` is used to guarantee more stablization time after a channel switch of arduino's internal ADC chip.

To deal with Nintendo Switch, I used the HID descriptor for Hori's Pokken fightstick to let Switch trust Arduino as a valid controller device (see the [credits](#credits) section). The default buttons from the four sensors are the analog stick buttons (press the sticks down) and the trigger buttons (ZL and ZR).

## Parameters (with suggested values)

#### min_threshold = 15
The minimum value for sensor levels to trigger inputs for all sensors.

To determine an optimal value for this level, try enabling debug info.
Usually, this value is only used to ignore sensor noises, but you can use this level as a sensitivity level.

#### cd_length = 10000
The cooldown length of sensors, in microseconds (=1x10^-6s).

While a sensor is in its cooldown period, no input will be triggered ignoring the sensor level. The threshold level would still be updated if the sensor levels go high.
During the cooldown period, the corresponding key of the sensor is kept pressed. When it ended, the key is released.

#### k_threshold = 1.5
How much the threshold value is raised to, in ratio to the sensor level.

#### k_decay = 0.97
How fast every threshold level decays, in ratio per refresh (about 300ms).

For every refresh, the threshold value is multiplied by k_decay.

#### pin[4] = {A0, A3, A1, A2}
The analog input pins of four sensors.

#### key[4] = {'d', 'f', 'j', 'k'}
The key mapping of four sensors, if keyboard inputs are enabled.

#### sens[4] = {1.0, 1.0, 1.0, 1.0};
Sensitivity of every sensor. All sensor levels are scaled by these values respectively before use.

## Debug Info

If the line ```#define DEBUG_OUTPUT``` is enabled, there will be debug info printed via serial. Take a look at your serial monitor.

The first 4 columns indicate current vibration level of the four sensors, and the last column indicates the threshold level for a sensor to trigger a input;
the symbols in the middle shows current status of the sensors, # for input triggered and * for cooldown state.

A typical output could be:

```
0  3  13 63 |         | 0
51 2  11 58 | * * * # | 53
83 5  9  24 | # * * # | 83
```

## Credits

- This sketch make use of Arduino IDE and its useful library. A modified version of the Arduino library is used to allow us to make a valid Nintendo Switch controller.
- The HID descriptor are a reverse engineering of Pokken Tournament Pro Pad of progmem's work: [progmem/Switch-Fightstick](https://github.com/progmem/Switch-Fightstick)
- The HID descriptor are coded using many useful macros and functions from [LUFA Library](http://www.fourwalledcubicle.com/LUFA.php)