Environment

Raspberry Pi 3 Model B, 32GB SD-card, Flatron IPS231 display, Rii i8 mini wireless keyboard/touchpad
Roland FP-30 piano
Ubuntu 18.04 LTS
Emteria.OS_Installer-v0.6-13.AppImage (Android 7.1)
Synthesia 10.5

Please keep in mind that the sequence described below presumes certain level of Linux and Android knowledge, e.g. how to mount SD-cards in Linux, how to edit Android boot configuration settings, or how to use Android Debug Bridge.

Make emteria.OS SD-card

Follow emteria.OS download and install instructions – you will be asked to create an Emteria account.

Emteria.OS license

If you decide to not yet pay for emteria.OS personal or business license, and use free evaluation license – be prepared to system reboots after 8 hours, and an evaluation license notice pop up now and then.

Modify HDMI settings in /boot/config.txt

Mount the SD-card in your Linux box, edit emteria.OS’s /boot/config.txt, enable safe HDMI configuration:

hdmi_safe=1

#hdmi_group=2
#hdmi_drive=2
#hdmi_mode=82
#hdmi_cvt=1024 768 60 6 0 0 0
#hdmi_force_hotplug=1
disable_overscan=1

dtoverlay=vc4-kms-v3d,cma-256
avoid_warnings=2

dtparam=sd_force_pio=on
dtparam=i2c1=on
dtparam=i2c_arm=on

dtparam=audio=on
audio_pwm_mode=2

initial_turbo=30
start_x=1
kernel=u-boot.bin

Save the changed /boot/config.txt file, unmount the SD-card.

Alternatively, you might want to configure all HDMI parameters manually – this is a rather tricky process which only worked for me with a dated non-HD resolution display.

Boot emteria.OS

Insert the emteria.OS SD-card into your Raspberry Pi, connect display, keyboard and mouse, power up.

For the next step your Raspberry Pi has to be connected to internet – via ethernet or wifi. In case of wifi – choose your wifi network and enter password, as usually in Android. Check internet connectivity in the emteria.OS browser.

Install Google Play

The emteria.OS comes without Google Play Store which we will need in the next step to install and unlock Synthesia. To install Google Play Store – follow the process explained here:

Google Play installation

In the EmteriaOS/Raspberry PI browser go to https://opengapps.org/
Select ARM, 7.1, pico, and click the Download button
When download is finished – click the Emteria.OS Power Off app icon, then Recovery
After Android reboots Swipe to Allow Modifications
Click Install
Go to the Download folder and click the downloaded open_gapps-arm-7.1.-pico-20180315.zip
Swipe to Confirm Flash
Click Reboot System after flashing is finished

After reboot – start Google Play and configure your Google account

You have to be patient while Android is busy with “System optimization in progress, please wait…” – it takes quite some time (longer than 1 day) and a few reboots, Android will be rather unresponsive all that time.

That might be that the “Sytem optimization…” message, the evaluation license pop ups, and Android’s lack of responsiveness would feel a bit frustrating, and you would probably want to try to reboot your Raspberry Pi – just to check that it did not go south incidentally. Here is a way how to do that (please also see the screenshots further below):

Go to Android Settings – Emteria, and switch on the “Enable ADB over Ethernet”
Note the IP address of your Raspberry Pi
On your Linux box:

### Connect
$ adb connect 192.168.1.144
connected to 192.168.1.144:5555
### Just checking if it's there
$ adb devices
List of devices attached
192.168.1.144:5555	device
### Reboot
$ adb reboot

Install Synthesia

I downloaded and installed Synthesia APK manually in the emteria.OS browser – to do that you need to go to generate Synthesia APK download link – the APK will be downloaded and installed.

Alternatively, you can install Synthesia from Google Play Store.

Unlock Synthesia

If you have Synthesia unlock key – unlock Synthesia as usually. For that you will need Google Play Store installed and your Google account configured, otherwise Synthesia complains it has no internet connection.