Jukebox¶

Jukebox is a subclass of EV3. You can use it to play tones or to change the LED color without internal knowledge of direct commands.

But Jukebox is more than that. It combines direct commands with thread_task. This allows to use sounds and light effects parallel to other activities.

Change Color¶

Instead of coding a direct command, like we did in Changing LED colors, you can do the same thing a bit more comfortable.

Connect your EV3 brick and your computer via Bluetooth, replace the MAC-address by the one of your EV3 brick, then start this program

import ev3_dc as ev3
from time import sleep

jukebox = ev3.Jukebox(protocol=ev3.BLUETOOTH, host='00:16:53:42:2B:99')
jukebox.verbosity = 1

jukebox.change_color(ev3.LED_RED_FLASH)

sleep(5)

jukebox.change_color(ev3.LED_GREEN)

For five seconds, the LED will flah red, then it will become green again. Calling method change_color() hides the technical details behind a more user friendly API. We set the verbosity because we like to see the communication between our program an the EV3 brick. The output:

13:09:05.718859 Sent 0x|08:00|2A:00|80|00:00|82:1B:05|
13:09:10.724762 Sent 0x|08:00|2B:00|80|00:00|82:1B:01|

Obviously, Jukebox sends direct commands.

Play Tone¶

Playing tones is the other competence of class Jukebox. Different from method tone() of class Sound, these tones are defined by their musical names and not by their frequencies. Method play_tone() allows to name them c, d, e, c’, d’ or e’. One does not need to know their frequencies.

Connect your EV3 brick and your computer via Bluetooth, replace the MAC-address by the one of your EV3 brick, then start this program

import ev3_dc as ev3

jukebox = ev3.Jukebox(protocol=ev3.BLUETOOTH, host='00:16:53:42:2B:99')
jukebox.verbosity = 1

jukebox.play_tone("f'''", duration=1, volume=100)

This plays f³ for one second at maximum volume (f³ is the highest tone of Mozart’s Queen of the night aria). If no duration is given, method play_tone() plays the tone unlimited. If no volume is given, it takes the volume, which was set as an optional argument of class Jukebox’s creation. If neither was set, it takes the volume from the device.

The output:

13:13:49.071839 Sent 0x|0F:00|2A:00|80|00:00|94:01:81:64:82:75:05:82:E8:03|

Playing the EU-Antemn¶

Connect your EV3 brick and your computer via Bluetooth, replace the MAC-address by the one of your EV3 brick, then start this program:

import ev3_dc as ev3

with ev3.Jukebox(protocol=ev3.BLUETOOTH, host='00:16:53:42:2B:99') as jukebox:
    jukebox.song(ev3.EU_ANTEMN).start()

Some remarks:

Method song() returns a thread_task.Task object, which can be started, stopped and continued. It plays tones and changes the LED-colors.

Starting the thread task does not block the program nor does it block the EV3 brick. It runs in the background and allows to do additional things parallel.

EU_ANTEMN is a dictionary:

EU_ANTEMN = {
    "tempo": 100,
    "beats_per_bar": 4,
    "led_sequence": (
        LED_ORANGE,
        LED_GREEN,
        LED_RED,
        LED_GREEN
    ),
    "tones": (
        ("a'", 1),
        ("a'", 1),
        ("bb'", 1),
        ("c''", 1),

...

        ("g'", 1.5),
        ("f'", .5),
        ("f'", 1)
    )
}

Some remarks:

tempo is beats per minute.

led_sequence is the color sequence, which changes per bar.

tones are the tones to play, the duration is not in seconds, but in beats.

Combine Happy Birthday with the Triad¶

Connect your EV3 brick and your computer via Bluetooth, replace the MAC-address by the one of your EV3 brick, then start this program:

import ev3_dc as ev3
from thread_task import Sleep

with ev3.Jukebox(protocol=ev3.BLUETOOTH, host='00:16:53:42:2B:99') as jukebox:
    (
        jukebox.song(ev3.TRIAD) +
        Sleep(1) +
        jukebox.song(ev3.HAPPY_BIRTHDAY) +
        Sleep(1) +
        jukebox.song(ev3.TRIAD)
    ).start()

The program builds a chain of tasks, which also is a thread_task object. It demonstrates how to build tasks of growing complexity, which still keep their simple public API.

Singing Canon with an EV3 brick¶

Connect your EV3 brick and your computer via Bluetooth, replace the MAC-address by the one of your EV3 brick, then start this program:

import ev3_dc as ev3
from thread_task import Repeated

with ev3.Jukebox(protocol=ev3.BLUETOOTH, host='00:16:53:42:2B:99') as jukebox:
    Repeated(
        jukebox.song(ev3.FRERE_JACQUES),
        num=3
    ).start()

Class Repeated plays the canon three times.