ev3-dc 0.9.4

EV3 direct commands

Use python3 to program your LEGO Mindstorms EV3. The program runs on the local host and sends direct commands to the EV3 device. It communicates via bluetooth, wifi or USB. I wrote a blog about this code.

There is no need to boot the EV3 device from a SD Card or manipulate its software. You can use it as it is, the EV3 is designed to execute commands which come from outside.

Installation

python3 -m pip install --user ev3_dc

Examples

Writing and sending direct commands

This program communicates via USB with an EV3 device (mac-address: ‘00:16:53:42:2B:99’, replace it by the the mac-address of your EV3) and plays a tone with a frequency of 440 Hz for a duration of 1 sec.

import ev3_dc as ev3

my_ev3 = ev3.EV3(protocol=ev3.USB, host='00:16:53:42:2B:99')
my_ev3.verbosity = 1
ops = b''.join((
    ev3.opSound,
    ev3.TONE,
    ev3.LCX(1),  # VOLUME
    ev3.LCX(440),  # FREQUENCY
    ev3.LCX(1000),  # DURATION
))
my_ev3.send_direct_cmd(ops)

The output shows the direct command, which was sent to the EV3 device:

11:48:31.188008 Sent 0x|0E:00|2A:00|80|00:00|94:01:01:82:B8:01:82:E8:03|

Subclasses of EV3 with comfortable APIs

Method play_tone of class Jukebox also plays tones:

import ev3_dc as ev3

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

This program does the very same thing via bluetooth! Before you can run it, you need to pair the two devices (the computer, that executes the program and the EV3 brick). The output:

11:55:11.324701 Sent 0x|0E:00|2A:00|80|00:00|94:01:01:82:B8:01:82:E8:03|

Independent Tasks

Specialized classes (e.g. class Jukebox) provide factory methods, that return thread tasks. Thread tasks allow to start, stop and continue independent tasks.

import ev3_dc as ev3

jukebox = ev3.Jukebox(protocol=ev3.WIFI, host='00:16:53:42:2B:99')
antemn = jukebox.song(ev3.EU_ANTEMN)

antemn.start()

This program plays the EU antemn. Before you can execute it, you need to connect both devices (the computer, that runs the program and the EV3 brick) with the same LAN (local area network), the EV3 brick must be connected via wifi. If you don’t own a wifi dongle, modify the protocol and select ev3.BLUETOOTH or ev3.USB.

Some remarks:

• Method song() returns a thread_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.

Read ev3_dc.readthedocs.io for more details.