Autor: Major Alvega

Nothing new here, just my personal notes with the LEGO Hub from 51515 MINDSTORMS Robot Inventor Set.

Most of it based on this post by Jason Jurotich.

I have a LEGO 51515 set, thanks to the ROBOTMAK3RS community (and still not sure yet if I am willing to pay so much money for this set).
I have an Android Lenovo tablet and an Android Samsung phone. Installed LEGO MINDSTORMS App on both but only can managed to use it on the phone – the tablet doesn’t get Activities so I could not even make Charlie play the drums.

I also have a Ubuntu Linux laptop. It will have to work – last time I revived a Windows 10 virtual machine it took me a whole night just to update it in order to install LEGO App. No way!!

So tanks to Jason post I can connect my laptop to the Hub:

sudo rfcomm connect hci0 A8:E2:C1:96:5B:9A

this gives me a ‘/dev/rfcomm0’ serial device and I can access the REPL environment in 2 different ways:

directly through a terminal client like ‘picocom’:

picocom /dev/rfcomm0 -b 115200

with a more proper tool like ‘rshell‘:

rshell -p /dev/rfcomm0 repl

When accessing the REPL, the hub is sending values so we need to Ctrl+C to get the prompt.

I found out that accessing the REPL through ‘picocom’ lead to strange behaviors afer a while (like commands being executed but not returning to the prompt and after a while not being able to access again, like if the Hub was rebooting immediately after accessing it) so I am now using ‘rshell’.

I also installed Adafruit ‘ampy’ from pypi. This way I can send and execute a micropython script from my laptop without accessing the REPL:

ampy --port /dev/rfcomm0 run test.py

But since I know nothing about LEGO micropython environment I will use REPL a while more (before flashing Pybricks on it and probably forgetting LEGO firmware like I did with MINDTORMS EV3 original application once I discovered ev3dev).

When accessing the REPL environment this is the welcome message:

Welcome to MicroPython!
 For online help please visit http://micropython.org/help/.
 Quick overview of commands for the board:
   hub.info()    -- print some general information
   hub.status()  -- print sensor data
 Control commands:
   CTRL-A        -- on a blank line, enter raw REPL mode
   CTRL-B        -- on a blank line, enter normal REPL mode
   CTRL-C        -- interrupt a running program
   CTRL-D        -- on a blank line, do a soft reset of the board
   CTRL-E        -- on a blank line, enter paste mode
   CTRL-F        -- on a blank line, enter filetransfer mode

of course ‘hub.info()’ and ‘hub.status()’ only work after we ‘import hub’ library – something probably obvious for someone used to (micro)python and REPL but not so obvious for newcomers.

Other important methods in this library

‘hub.battery.info()’:

>>> hub.battery.info()
{'temperature': 23.8, 'charge_voltage': 7591, 'charge_current': 251, 'charge_voltage_filtered': 7583, 'error_state': [0], 'charger_state': 0, 'battery_capacity_left': 80}         

‘hub.repl_restart()’ – I had used this method a few times today… and I hate reboots!

‘hub.power_off()’

So lets find out if I can make Charlie play the drum with micropython.

… and again and again 😀

So the LEGO Laser Harp v2 is almost done. A few more bricks here and there.

But it the meanwhile I had to test my MIDI ideas… and got a MiDiPLUS miniEngine USB as a cheap portable MIDI sound engineso I don’t have to use a computer (yeah… as if!)

Then I got back to the MINDSTORMS pneumatic pressure sensor idea and made a sort of LEGO MIDI Trumpet:

Then I got carried away and made my own LEGO MIDI Drum Kit:

All these using USB MIDI Adapters and plain MIDI equipment (I now also have a MIDI Merger). Even joined my MIDI keyboards to the MIDI network thanks to Patchbox OS running on a Raspberry Pi with a USB MIDI adapter for the older keyboard (DIN5) and plain USB cables for the newer ones.

But the original idea was making MIDI instruments without cables and gadgets (except for the WiFi dongle) so I got a little back again and made a few tests with multimidicast (ipMIDI).

The Drum Kit works great with MIDI cables… but extremely bad with ipMIDI when using the Raspberry Pi with Patchbox OS as an ipMIDI gateway. High latency and poor sensibility when using MODEP software generators.

So gave up MODEP and jack and used just a USB MIDI adapter to connect the ipMIDI gateway to the MiDiPLUS miniEngine USB. Much better… but still some latency.

So I just need to make a few more adjustments to finish my LEGO ipMIDI Drum Kit. Then will test how this thing scales out with more ipMIDI instruments.

Using ev3dev and python to speak a few words in english in english is very easy:

from ev3dev2.sound import Sound
sound = Sound()
sound.speak('Good morning')

Making it speak portuguese words is also easy:

from ev3dev2.sound import Sound
sound = Sound()
sound.speak('Bom dia', espeak_opts='-v pt')

not a great pronounce but still understandable.

Problems started when trying to speak sentences written with portuguese characters like “Olá” (“Hello”)

sound.speak('Olá', espeak_opts='-v pt')

it generates an error similar to this:

UnicodeEncodeError: 'ascii' codec can't encode character u'\xa0' in position 20: ordinal not in range(128)

my ev3dev installation wasn’t configured to understand non-ASCII characters so a quick setting at the command line corrected this:

$ export LC_ALL="en_US.UTF-8"
$ export LC_CTYPE="en_US.UTF-8"

Now I wanted to speak the current date, like ‘Today is Friday 25 December” so I found ‘datetime’

from datetime import datetime as dt
import datetime

today = dt.today()
speech = today.strftime("%A") + ' ' + today.strftime("%-d") + ' ' + today.strftime("%B")
sound.speak('Today is ' + speech)

Great. At least in english. But how to do it in portuguese (i.e. ‘Hoje é Sexta 25 Dezembro”)? How to make today.strftime(“%A) return “Sexta” instead of “Friday”?
The trick is using ‘locale’:

from datetime import datetime as dt
import datetime
import locale

locale.setlocale(locale.LC_TIME, "pt_PT") 
today = dt.today()
speech = today.strftime("%A") + ' ' + today.strftime("%-d") + ' ' + today.strftime("%B")
sound.speak('Today is ' + speech)

And now another error:

locale.Error: unsupported locale setting

ev3dev doesn’t have Portuguse locale settings (we can check with ‘locale -a‘). So I needed to install them:

$ sudo dpkg-reconfigure locales

Have been using Pybricks a bit – with some of my MINDSTORMS EV3 (mostly because micropython is much more quick to start than full python) but also with a few Powered Up hubs I own (partly because I don’t like the idea of using Apps but also because micropython is much more clean).

Lately I realized how great this project is by offering us a common framework for the different LEGO programmable devices instead of using an App for BOOST, City and Control+ hubs and another App for SPIKE and/or Robot Inventor and python or Scratch for EV3 and who knows what LEGO will release next.

So if by any chance you are reading this you might also like to know that Pybricks is accepting support through github’s sponsors:

In their own words: