Amadeus hack

Lichee RV dock pinout

Hardware BOM:

• Chicco Teddy orso delle emozioni
• Sipeed Lichee RV
• Loudspeaker (4 or 8 ohm)
• 5V power bank

Software

Software BOM:

• OS: to date, the cleanest OS available seems to be the official Ubuntu port
• gpiod
• MPD: Music Player Daemon

gpiod

gpiod provides a set of handy command line tools to manage the GPIO interface. Out of the box, such tools require root permissions to work. To enable a standard user to run gpiod utilities, create a dedicated group and add the standard user to it:

sudo groupadd gpio
sudo usermod -G gpio <user>

Then create a new udev rule:

#!/bin/bash
cat <<EOF >/etc/udev/rules.d/60-gpiod.rules
    SUBSYSTEM=="gpio", GROUP="gpio", MODE="0660"
    SUBSYSTEM=="gpio", KERNEL=="gpiochip*", ACTION=="add", PROGRAM="/bin/sh -c 'chgrp -R gpio /sys/class/gpio && chmod -R g=u /sys/class/gpio'"
    SUBSYSTEM=="gpio", ACTION=="add", PROGRAM="/bin/sh -c 'chgrp -R gpio /sys%p && chmod -R g=u /sys%p'"
EOF

To identify the GPIO lines to be used in gpiod, run sudo cat /sys/kernel/debug/pinctrl/2000000.pinctrl/pinmux-pins:

Pinmux settings per pin
Format: pin (name): mux_owner|gpio_owner (strict) hog?
pin 32 (PB0): UNCLAIMED
pin 33 (PB1): UNCLAIMED
pin 34 (PB2): UNCLAIMED
...

For example, to set PB0 high, run:

sudo gpioset 0 32=1

Start-up sequence (through systemd):

1. start the MPD daemon
2. setup MPC and lights, play random song, sleep, fade out and stop playing

The following scripts will be running together:

1. monitor switch 1
2. monitor switch 2
3. monitor switch 3
4. monitor switch 4

Each monitor script has the following structure:

function action {
    # check if music is playing
    mpc | grep playing
    status=$?
    #if YES
    if [ "$status" == 0 ]; then
        mpc next    # bottom right: <PIN>=PD12
        mpc prev    # bottom left: <PIN>=PD13
        mpc volume +10  # upper right: <PIN>=PD15
        mpc volume -10  # upper left: <PIN>=PD17
    #if NO, resume playing
    else
        /bin/bash /home/ubuntu/scripts/replay.sh &
    fi
}

for((;;))
do
    gpiomon --bias pull-down -s -n 1 -r 0 <PIN> && action
    sleep 0.7
done