Things used in this project

Hardware components:
11113 01
SparkFun Arduino Pro Mini 328 - 5V/16MHz
×1
Adafruit LIS3DH Triple-Axis Accelerometer
×1

Schematics

firebending schematic
Circuit diagram of the firebending brains. Note that the solenoid is the solenoid valve, and the piezo buzzer is a stand in for the arc lighter.
Firebending schem hufmj1tsrx

Code

firebending.inoC/C++
Arduino sketch for a punch detecting flamethrower.
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_LIS3DH.h>
#include <Adafruit_Sensor.h>

// Used for software SPI
#define LIS3DH_CLK 13
#define LIS3DH_MISO 12
#define LIS3DH_MOSI 11
// Used for hardware & software SPI
#define LIS3DH_CS 10

//software SPI
Adafruit_LIS3DH lis = Adafruit_LIS3DH(LIS3DH_CS, LIS3DH_MOSI, LIS3DH_MISO, LIS3DH_CLK);

//A fist experiences significant acceleration during a good punch,
//followed by massive deceleration at the end of the punch.
//This happens within a fairly small window of time, so it's
//pretty easy to distinguish a punch from normal gesticulations.

unsigned long punchStart = 0;//variable for non-blocking punch timeframe check
const long punchInterval = 200;//timeframe of a punch in ms, from max acceleration to max deceleration, 200 is very generous
int punchAccel = 20;//the beginning of a punch in m/s^2, could be over 50m/s^2 depending on the puncher
int punchDecel = -40;//the end of a punch in m/s^2, could be less than -100m/s^2 depending on the puncher
int flameTime = 250;//how long the flame lasts, in ms

void setup(void) {
  //Test to see if accelerometer is communicating
  Serial.begin(9600);
  Serial.println("LIS3DH test!");  
  if (! lis.begin(0x18)) {   // change this to 0x19 for alternative i2c address
    Serial.println("Couldnt start");
    while (1);
  }
  Serial.println("LIS3DH found!");
  
  lis.setRange(LIS3DH_RANGE_16_G);   //+-16G range for good punch detection
  Serial.print("Range = "); Serial.print(2 << lis.getRange());  
  Serial.println("G");
  
  pinMode(8, OUTPUT); //Solenoid valve
  pinMode(9, OUTPUT); //Arc lighter
  digitalWrite(8, LOW);
  digitalWrite(9, LOW);
}

void loop() {
  lis.read();
  sensors_event_t event; 
  lis.getEvent(&event);
  
 //look for punch starting, at least 20 m/s^2
  if (event.acceleration.x > punchAccel){
     Serial.println(event.acceleration.x);
     punchStart = millis();
  }
  
  unsigned long currentMillis = millis();

  //look for punch ending, less than -40 m/s^2
  if (event.acceleration.x < punchDecel && currentMillis - punchStart < punchInterval){
      Serial.println(event.acceleration.x);
      Serial.println("Punch");
      Fire(flameTime);
    }
}

void Fire(int flameTime){
  digitalWrite(8, HIGH);
  digitalWrite(9, HIGH);
  delay(flameTime);
  digitalWrite(8, LOW);
  digitalWrite(9, LOW);
}

Credits

Myththumb krtcfg2bgz
Allen Pan
1 project • 478 followers
My name's Allen, I make pretend things into real things! Watch me do a thing on Youtube!
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