Automated Xylophone

Team Members

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• Brandon Robins (Senior in Mechanical Engineering and Music Performance, Northwestern University)
  
• Neil Tiwari (Masters Student in Biomedical Engineering and Kind of a Big Deal, Northwestern University)
  
• Jenny Yong (Senior in Mechanical Engineering, Northwestern University)
  

Overview

The goal of this project was to have a user input a sequence of notes and have a PIC controlled solenoid sytem hit a xylophone to generate tones. Our automated xylophone operates in two settings -- real time mode and playback mode. In real time mode, the user inputs notes using the keypad and they get played back on the xylophone instantaneously. In playback mode, a user can use the keypad and LCD screen to verify and store over 250 notes in sequence including rests to be played back on the xylophone at a later time.

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Operating the Automated Xylophone

[Include picture for description of keypad] The user interface includes a keypad containing 16 buttons, arranged as seen above.

Real Time Mode

In Real Time Mode, buttons 1-8 are used to determine xylophone note. As soon as a button is depressed, it will immediately trigger a solenoid to play the chosen note.

Playback Mode

To enter playback programming mode, you hit button 16 -- the edit button. Playback programming mode allows you to store 256 notes, including rests, per block. Once in edit mode, you have access to buttons 1-12. As in Real Time Mode, buttons 1-8 still determine which note should be played. Buttons 9 and 10 will adjust the note duration to shorter and longer respectively. Buttons 11 and 12 will adjust the which sequential number is being programmed. Button 11 will lower the note number, while button 12 will increase the note number. Rests can be programmed using button <n>. To enter and store a note, you use the enter button, button <m>. Once you have finished entering the string of notes you would like to store, you hit button <o>.

To listen to the stored song, you hit button 16, the edit button again.

Parts List

Coming soon . . .

The Xylophone

The xylophone that we selected can be found and purchased here.

Mechanical Design

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Mechanical Interface

Our mechanical design was fairly simple and straightforward. We needed to determine the optimal way for the solenoids to hit the xylophone keys, and a way to support them in that position. Initially, we found it to be most intuitive for the solenoids to strike downward onto the keys. However, that design would require us to keep the solenoids powered during rest. Therefore, we choose to have our solenoids strike from below the xylophone which allows us to keep them powered off while inactive.

One feature of our mechanical design is that with the xylophone chosen as the bars are hit, the piano keys depress. This design creates the appearance of a phantom piano player.

Solenoid Positioning

To improve aesthetics and support the xylophone at the proper height, we created a wooden housing for the solenoids. Within the housing, our solenoids rest on an aluminum beam which hold them at the appropriate height. On our aluminum beam, we have a ladder-like structure made of foam core to hold the solenoids in place.

Tape was also placed around the piston of the solenoids, as can be seen in the photos. This technique was a temporary solution to prevent the solenoids from banging on the aluminum beam and keep them at an operable height once powered at 12 V. The xylophone is placed on top of the wooden housing with the bars properly aligned with the solenoids.

Electrical Design

Circuit Diagram

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Creating the Automated Xylophone did require some intricate circuitry, as can be seen in the picture of our circuit and our circuit diagram. The most complicated aspects included powering our solenoids using an external power supply and relays, connecting the LCD screen to our PIC and using an EEPROM to store our song information in playback mode. More detailed descriptions of these steps can be found below.

Powering the Solenoids

Since the solenoids need to operate at full voltage and required a lot of current, we were unable to power them using the PIC. Instead, we worked with an external power supply and relays.
[More description needed]

Connecting the LCD

The LCD screen allows the user to monitor his progress in programming for Playback Mode.
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Using an EEPROM

For our Automated Xylophone, an EEPROM is used to store all of the note information during playback mode. More information on connecting an EEPROM to a PIC can be found here and here.

Code

Multiplexing

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Commented Code

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Results and Next Steps

Results

Our Automated Xylophone operated as expected, with full capability in both Real Time Mode and Playback Mode. We were also able to get excellent sound on our xylophone. A video of our Automated Xylophone playing in Real Time Mode can be found here. A video of our Automated Xylophone playing in Playback Mode can be found here.

Next Steps

Given more time, potential next steps include:

• Allowing the keypad to use wireless connectivity to send information to the xylophone
  
• Creating an enclosure for the circuitry
  
• Creating a more permanent housing for the solenoids and xylophone
  
• Incorporating the RGB LEDs on the Keypad