Mycroft Mark II

body / case

The original mark2 body at ​https://github.com/MycroftAI/hardware-mycroft-mark-II-rpi was not printable on my FDM printer. So I used this: ​https://community.mycroft.ai/t/simplified-mark-ii-body-for-fdm-printing/8248/12 or ​https://github.com/guhl/hardware-mycroft-mark-II-rpi

Software basis

I used the picroft image Picroft_Buster-Keaton_2020-01-10.img as the software basis

Audio

I had two problems related to audio.

First the volume of the Adafruit MAX9744 Amplifier was very high and resulted in a general cracking and static noise when switched on.

And in addition the volume control did not influence the volume of the Mycroft output

Mycroft Mark II - Sound

Adafruit Volume control

I am controlling the volume of the MAX9744 using the CircuitPython Libraries (see ​https://learn.adafruit.com/circuitpython-on-raspberrypi-linux/installing-circuitpython-on-raspberry-pi ). The things that I had to do:

Install the library

while in (.venv)

• pip3 install RPI.GPIO
• pip3 install adafruit-blinka

Enable I2C ===

I2C is not enabled by default so run and enable I2C in the Interfacing Options

Python script

Use this script to set the initial volume to about the half (the range is 0 to 63). Create ~/bin/ada_volume.py with the following content

• nano ~/bin/ada_volume.py

  import board
  import busio
  import adafruit_max9744
  i2c = busio.I2C(board.SCL, board.SDA)
  amp = adafruit_max9744.MAX9744(i2c)
  amp.volume = 30
  

Start using systemd

Place a service file in the user directory:

• nano ~/.config/systemd/user/myadavolume.service

with the content

[Unit]
Description=set adafruit volume
After=network.target

[Service]
Type=simple
ExecStart=/home/pi/mycroft-core/.venv/bin/python /home/pi/bin/ada_volume.py

[Install]
WantedBy=default.target

Enable and start it:

• systemctl --user daemon-reload
• systemctl --user enable myadavolume
• systemctl --user start myadavolume

Pulseaudio

The picroft installation does not use pulseaudio for the output of voice and other sound so the general volume control did not work

blacklist the internal bcm2835 sound card

This is for sure totally optional but I did it

• sudo nano /etc/modprobe.d/alsa-blacklist.conf

  blacklist snd_bcm2835
  

force ALSA userspace to use PulseAudio

• sudo nano /etc/asound.conf

  # Use PulseAudio by default
  pcm.!default {
    type pulse
    fallback "sysdefault"
    hint {
      show on
      description "Default ALSA Output (currently PulseAudio Sound Server)"
    }
  }
  
  ctl.!default {
    type pulse
    fallback "sysdefault"
  }
  

mycroft conf

• sudo nano /etc/mycroft/mycroft.conf

replace:

   "play_wav_cmdline": "aplay -Dplughw:ArrayUAC10,0 %1",
   "play_mp3_cmdline": "mpg123 -a plughw:ArrayUAC10,0 %1",

with

   "play_wav_cmdline": "paplay %1",
   "play_mp3_cmdline": "mpg123 %1",

additional setting in default.pa

This enables ducking and is a nice feature that the volume of music playing is turned down while Mycroft speaks instead of stopping the output.

• sudo nano /etc/pulse/default.pa

add to the end of the file

unload-module module-suspend-on-idle
unload-module module-role-cork
load-module module-role-ducking