Servo - April 2012

voltage. Though the MIDI output is stereo, I’m showing it using only one output channel.

Use a small self-powered amplifier, like the capsule type in Figure 10. These amps contain their own rechargeable battery. Connection to the Parallax line follower module is shown in Figure 11. The line follower module contains an

onboard sensitivity adjustment; set it to give you the greatest range. See the documentation for the module for additional information.

The Tunebot uses a sketch called MIDI_Piano. The program listing is too lengthy to reproduce here; you can download it at the article link.

To use the Tunebot, upload its sketch to the Arduino, plug in power to the servos, and set the robot on the ground. Simple movement patterns over the line follower module control the bot: • Pass your fingers over the center sensors to make the robot go forward. Activate the center sensors again and the robot reverses direction.

Experiment with the line sensor coding to add other finger gesture controls. For example, you might add code that listens for a specific three or four note tune in order to activate the Tunebot. Create some code to play your favorite songs while the Tunebot is moving.

Add sound effects – use instruments from the drum bank – and sound them off in response to other sensors you’ve attached to the robot. How about a cymbal crash when a bumper switch is activated. Or, maybe the slide of a trombone to indicate distance from an ultrasonic rangefinder. Figure 12 shows an alternative version of the Tunebot, with several sensors mounted on the front to detect nearby objects.

Adding Digitized Sounds, Music, and Effects

MIDI is a wonderful method of adding music to your robot, but it’s not the only technique you can use. A number of Arduino shields and breakout boards allow you to reproduce sound from MP3 and other kinds of digitized clips. Next time around, we’ll talk about adding recorded voice, music, and sound effects to your Arduino-based robot. SV