Gesture Controlled Metronome for Guitar Practice

Funk guitars are usually played with a percussive mindset so the use of a metronome for practices is kind a must. After several years with a classic Wittner Taktell piccolino metronome - and inspired by Arduino Day #2021 - I’ve decided to make Betty, my own Arduino based metronome, with the following features:

• Hand gestures or even better: guitar neck gestures
• Easily increase and decrease tempo by 5 BPM
• Record and display practicing time for each session

Why Betty?

I don’t usually put names to devices but this time I just wanted to make a small tribute to Betty Davis, the funk queen – and former Miles Davis wife (not that this matters at all, but just a reference)

Parts:

• Heltec WiFi Kit 8 (ESP8266 with integrated Oled 128x32 screen) - I’ve used WiFi Kit 8 since I did not have an Oled screen available but you can use any other Arduino with an external Oled screen.
• 5V Buzzer
• DF Robot Gravity Gesture Sensor PAJ7620U2
• Custom made 3d printed case - optional
• DC In female connector - optional, you can also power it up with anyUSB cable

Connections:

• Buzzer: D7 and GND
• Gesture: VCC, GND, SDA D2, SCL D1
• VIN: 5V and GND
• DC female: to GND and 5V

Gesture control

PAJ7620U2 is an interesting little device made by DFRobot. It is able to recognize Right, Left, Up, Down, Forward, Backward, Clockwise, Anti-Clockwise, Wave, WaveSlowlyDisorder, WaveSlowlyLeftRight, WaveSlowlyUpDown and WaveSlowlyForwardBackward, so it can be used for menu navigation instead of soldering several buttons

The DFRobot_PAJ7620U2.h library simplifies the entire procedure. You just place this code in the loop and that’s it.

DFRobot_PAJ7620U2::eGesture_t gesture = paj.getGesture();
if(gesture != paj.eGestureNone ){
    String description  = paj.gestureDescription(gesture);
    if (description=="Right"){
        // right detected here
    }
}

Delay calculation

The main part of this project is to calculate the delay between sounds and that is done with this function.

unsigned long myDelay=(1000)/(bpm/60);

Operation

To increase the metronome tempo just make an Up gesture with the guitar. To decrease make a Down gesture. Right to start and Left to stop.

Demo video

Where to go from here

You can add a mini plug output for console or headphones and generate the sounds from Mozzi library. You can also add new gestures to reset practice time or increase tempo by 10, etc