What is it?

The ODroid Go Advance is a handheld that runs a linux operating system. The image I am running is a version of Ubuntu 20.04. HardKernel makes the device: https://www.hardkernel.com/shop/odroid-go-advance-black-edition/. It's great for playing emulated game systems and I thought it would be even better if I could listen to the radio on it :)

This repo is an attempt to make something a little nicer than the hacked up script I run now that only lets me play one radio station without ssh'ing into the device to alter what plays.

This program should minimally:

• [X] Allow a FM radio station to be played.
• [X] Allow the changing of the station using the controller.
• [X] Allow changing the volume. Shout out to (https://github.com/zfteam/hotkey_for_oga); stole their trick to alter the volume.
• [X] Show what station is playing.
• [X] Lower the backlight while idle to reduce battery use.
• [X] Read/Write a configuration file to alter running behavior.
• [X] Allow presets/bookmarks to be jumped to and added/deleted to make navigating frequencies easier.

External Requirements

This also requires some RTL-SDR USB device to plug into the Go Advance. I'm using one from Adafruit from here: https://www.adafruit.com/product/1497 There are tons of these things around, so that particular one isn't a requirement; but you must have one.

Configure RTL-SDR

The USB dongle can't be used by the odroid user by default; it can only be accessed with root privileges. The first part of this involves a set of udev rules from the docs/rtl-sdr.rules file. Copy these into /etc/udev/rules.d/ folder. Note that all of the rules allow access if a user is in the plugdev group. So let's add the odroid user to that group:

 sudo usermod -a -G plugdev odroid

Now you should be able to access and see the USB device as the odroid user.

Important: You'll need to reboot the odroid to have access.

Build

Prereqs

This assumes a sudo apt update has been run recently. Unfortunately, the latest image HardKernel has put out has regressed in Ubuntu version from 20.04 to 18.04. This means there are some extra steps that need to be taken to get a more recent version of gcc.

These packages are required to build this program:

sudo apt install git build-essential

For Ubuntu 18.04 we also need to install gcc and g++ version 9. The steps are (see here for more information - https://linuxize.com/post/how-to-install-gcc-compiler-on-ubuntu-18-04/):

sudo apt install software-properties-common
sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt install gcc-9 g++-9
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-9 90 --slave /usr/bin/g++ g++ /usr/bin/g++-9 --slave /usr/bin/gcov gcov /usr/bin/gcov-9

Additionally, the libbladerf-dev version in Ubuntu 18 is from 2016; we need the latest so:

sudo add-apt-repository ppa:bladerf/bladerf

If you have already installed the libbladerf-dev package, then upgrade it via:

sudo apt upgrade

These packages are required to build the ngsoftfm program:

sudo apt install cmake pkg-config libusb-1.0-0-dev libasound2-dev libboost-all-dev librtlsdr-dev libhackrf-dev libairspy-dev libbladerf-dev

Get the code

Pull down the submodules.

git submodule update --init --recursive

This requires the libgo2 library from: https://github.com/OtherCrashOverride/libgo2 It should already be on the ODroid Go Advance.

The program consists of two main parts, the UI application and the softfm application it controls.

Build go2radio

To build the UI application run:

make

Build NGSoftFM

To build the softfm application detailed instructions are inside the lib/ngsoftfm/ directory including additional packages. The program expects the softfm program to be in lib/ngsoftfm/build/.

Simplified instructions are here:

cd lib/ngsoftfm
mkdir build
cd build
cmake ..
make

Install

Clone the repo and copy over to the go advance (or clone directly on the go advance). Do the build.

Now there are two options to get it into the carousel to run:

1. An additional program within the settings gear menu.
2. Add another system into the carousel just for this and potentially other programs.

Option 1 - Existing Settings Gear

Put a shell script in /opt/system/ called something like go2radio.sh with the path to the built go2radio binary.

/home/odroid/src/go2radio/go2radio

Make the script executable:

chmod +x /opt/system/go2radio.sh

You can now run it from the gear menu like the network app and others.

Option 2 - Add another Gear

This option is really only necessary if you want to alter how the programs run. Some emulators turn the performance to max, run itself and then turn it back to normal. I'm playing with this to see if it fixes the audio blips that randomly occur, but isn't normally necessary.

Make a copy of the /etc/emulationstation/es_systems.cfg

cp /etc/emulationstation/es_systems.cfg /home/odroid/.emulationstation/.

Then add an additional system at the end still inside the <systemList> </systemList> tags.

<system>
        <name>retropie</name>
        <fullname>Apps</fullname>
        <path>/home/odroid/apps</path>
        <extension>.sh</extension>
        <command>perfmax;%ROM%;perfnorm</command>
        <platform></platform>
        <theme>retropie</theme>
</system>

Note the path /home/odroid/apps and create it.

Next create a script like in Option 1, but place it insie the /home/odroid/apps folder instead.

There will be an additional gear menu that has the program in it.

Configuration

On the first run of the program it will create a configuration file in ~/.go2radio/config. The following text will be defaulted:

# Describes how long to wait on inactivity before changing
# the brightness level.
idle_time=30
# A level of 0 means no backlight and 100 is full.
brightness_idle=1
brightness_active=50
# The min/max frequencies in Hz.
frequency_min=88100000
frequency_max=107000000
frequency_start=88100000
# How to display the frequency in MHz.
frequency_display_format=%.1f
# How long to let the softfm program run before attempting
# to kill it in seconds.
tune_kill_sleep_time=5
# How long the tune button must be held before it
# transitions to the fast increment speed.
tune_increment_trans_time=2
# The amount to increment in Hz.
tune_increment_normal=100000
tune_increment_fast=1000000
# The path to the softfm program.
softfm_path=lib/ngsoftfm/build/softfm
# The arguments to pass to the softfm program specific to
# the RTL-SDR inputs; at a minimum it must have:
# 'freq=%d' for the correct frequency to be passed.
softfm_args=freq=%d gain=auto
# How much (in pixels) to indent on both sides.
bookmark_margin=20
# How many bookmarked stations to show in one row.
bookmark_cols=7
# How many pixels to space between bookmarked stations.
bookmark_separation=5

Feel free to play around with these to obtain different visuals on some of the displayed values (frequency_display_format) or increment values.