Raspberry Pi connected Wii Balance Board sends weight to Google Docs spreadsheet, shows it on an LCD and outputs text to speech
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README.md

rpiscale

Raspberry Pi connected Wii Balance Board sends weight to Google Docs spreadsheet, shows it on an LCD and outputs text to speech

I had a balance board sitting around I built an Internet connected weighing scale based on https://github.com/skorokithakis/gr8w8upd8m8

I have used a Raspberry Pi 2 with Arch Linux with a LogiLink Bluetooth 4.0, Adapter USB 2.0 Micro and an 84x48 Nokia LCD Module Blue Backlight Adapter PCB with a SPI interface.

This project should work on any Linux distribution and platform with adjustments but I have included detailed instructions for my setup.

Installing:

Follow the steps on to install Arch Linux https://archlinuxarm.org/platforms/armv7/broadcom/raspberry-pi-2#installation

After installing please change the default user passwords (root and alarm) to prevent your Pi becoming a botnet zombie.

Update the packages

pacman -Syy && pacman -Syu --noconfirm

Bluetooth installation

pacman -S --noconfirm bluez bluez-utils
systemctl enable --now bluetooth

Pair the board using bluetoothctl and enable the agent to connect the board when you press the balance board button

power on
agent on
default-agent
scan on

Press the sync button on the board (under the battery cover), replace xx:xx:xx:xx:xx:xx with the MAC address that appears on screen

pair xx:xx:xx:xx:xx:xx
trust xx:xx:xx:xx:xx:xx
exit

To set the bluetooth adapter to be powered on during startup add AutoEnable=true in the [Policy] section of /etc/bluetooth/main.conf

More info here https://wiki.archlinux.org/index.php/bluetooth#Bluetoothctl

Obsolete bluetooth settings for bluez older than 5.44

For the bluetooth adapter to be powered on during startup create /etc/udev/rules.d/10-local.rules

### Set bluetooth power up
ACTION=="add", KERNEL=="hci[0-9]*", RUN+="/usr/bin/hciconfig %k up"
You may need to edit systemd-udevd.service for the bluetooth udev rule to work, if it does not powers on at start up, add AF_BLUETOOTH at end of RestrictAddressFamilies
systemctl edit --full systemd-udevd.service

For me the line looks like

RestrictAddressFamilies=AF_UNIX AF_NETLINK AF_INET AF_INET6 AF_BLUETOOTH

Python2

pacman -S --noconfirm python2-pip
pacman -S --noconfirm python2-numpy
pacman -S --noconfirm python2-gdata
pacman -S --noconfirm python2-systemd
pacman -S --noconfirm freetype2
pacman -S --noconfirm python2-pillow
Xwiimote

Install build dependencies

pacman -S --noconfirm base-devel git ncurses swig

Build and install xwiimote and xwiimote-bindings

git clone https://github.com/dvdhrm/xwiimote
cd xwiimote
./autogen.sh --prefix=/usr
make
make install
cd
rm xwiimote -rf

git clone https://github.com/dvdhrm/xwiimote-bindings
cd xwiimote-bindings
./autogen.sh --prefix=/usr
make
make install
cd
rm xwiimote-bindings -rf
LCD screen

Screen connections:

Screen pin RST CE DC DIN CLK VCC LIGHT GND
Board pin 18 24 16 19 23 17 29 25
BCM pin GPIO24 GPIO8 GPIO23 GPIO10 GPIO11 3v3 GPIO5 GND

Enable the SPI interface by adding to /boot/config.txt

device_tree_param=spi=on

Install RPi.GPIO

pip2 install RPi.GPIO

Install Adafruit_GPIO from sources (current version 1.0.3) and not from pip (version 1.0.1) because the pip version it does not properly detect the raspberry with kernel 4.9.13

pip2 install git+https://github.com/adafruit/Adafruit_Python_GPIO

Build and install Adafruit_Nokia_LCD

git clone https://github.com/adafruit/Adafruit_Nokia_LCD.git
cd Adafruit_Nokia_LCD
python2 setup.py install
cd
rm Adafruit_Nokia_LCD -rf

Postgresql

Set the utf8 locale
sed -i 's/#en_US.UTF-8/en_US.UTF-8/' /etc/locale.gen
locale-gen
localectl set-locale LANG=en_US.UTF-8
Install Postgresql and create the database
pacman -S --noconfirm postgresql
pacman -S --noconfirm python2-psycopg2

chown -R postgres:postgres /var/lib/postgres/
runuser -l postgres -c "initdb --locale en_US.UTF-8 -E UTF8 -D '/var/lib/postgres/data'"
systemctl enable --now postgresql
runuser -l postgres -c "createdb rpiscale"
runuser -l postgres -c "createuser -S -D -R -e rpiscale"

Speech engine

pacman -S --noconfirm espeak
pacman -S --noconfirm alsa-utils
pip2 install pyttsx

Sound volume boost

I found the output volume of the RPi with a passive speaker too low.

Enable the audio interface by adding to /boot/config.txt

dtparam=audio=on

Create /etc/asound.conf

pcm.softvol {
        type softvol
        slave.pcm "cards.pcm.default"
        control {
                name "Software"
                card 0
        }
        max_dB 25.0
}
pcm.!default {
        type            plug
        slave.pcm       "softvol"
}

Set the volume and save it to make the changes permanent

alsactl init
aplay -l
amixer sset 'PCM' 100%
amixer sset 'Software' 100%
alsactl store

Check it with alsamixer

Project service

Checkout the project. Go to the project folder

Create database tables

psql -U rpiscale < create_tables.sql

Create a blank Google spreadsheet https://docs.google.com/spreadsheets/u/0/

Get the spreadsheet_id from the spreadsheet link ''' https://docs.google.com/spreadsheets/d/*spreadsheet_id*/edit#gid=1023436007 '''

If you need them create more sheets. Enter in each sheet in the first column first row cell date and the second column first row weight

Get the sheets ids from

https://spreadsheets.google.com/feeds/worksheets/*spreadsheet_id*/private/full

inside the id tags in the form of

<id>https://spreadsheets.google.com/feeds/worksheets/*spreadsheet_id*/private/full/*sheet_id*</id>

The first sheet_id is always od6

Go to https://console.developers.google.com/apis/credentials , create a project if you need to and create a new OAuth 2.0 client ID for Other. Get the ClientID and Client secret.

Edit the config.py file and add your spreadsheet_id, gdata_client_id and gdata_secret.

Configure the sheets to match your spreadsheet file. You can have as many as you like as long as the weight ranges (the fourth parameter) do not overlap except for the last one set as a catch-all.

Edit disconnect.txt and replace xx:xx:xx:xx:xx:xx with the MAC address of your balance board

Run python2 rpiscale.py turn on the balance board, the LCD should light up. Stand still on the board until you hear over 5 beeps. Get off it and you should see a link on the terminal.

Open that link in a browser to get the authorize token. Enter the authorize token into the prompt. This stores the token so you only have to do this once.

Press Ctrl+c to end the script.

If the balance board does not connect, try the button again a few times, check the batteries, check the bluetooth adapter is up with hcitool dev and if it does not appear, bring it up with hciconfig hci0 up and redo the paiting/trust sequence.

Create /etc/systemd/system/rpiscale.service (adjust the script path to match your setup). If you use the LCD screen you need to run it as root.

[Unit]
Description=Raspberry Pi Scale Service
After=postgresql.service bluetooth.service

[Service]
ExecStart=/usr/bin/python2.7 /root/rpiscale/rpiscale.py
PIDFile=/run/rpiscale.pid

[Install]
WantedBy=multi-user.target

Start at boot

systemctl enable --now rpiscale

Attribution

I am using these Creative Commons fonts:

and this sound clip: