pi-media-remote

Overview

This repo allows you to make a Pi Zero W (2) appear as a USB media remote control. It can then be plugged into devices like an Android TV or Fire TV and used to control it over the network.

Requirements

1. A Rasberry Pi Zero W or Rasberry Pi Zero W 2 (it may also work with a Pi 4 but I've not tested this)
2. A way to connect the Pi Zero to the device to be controlled.
   • For Fire TV I used this cable: FireTv OTG Cable
   • For Google Ghromecast with Android TV I use this adapter: Chromecast with Google TV OTG Cable. This also allows you to use Wired Ethernet

Installation

Operating System

First install a minimal Linux OS on the Raspberry Pi Zero - I use DietPi with no extra software installed and connect it to your WiFi.

Clone the repo

ssh to your pi and clone the repo

cd ~
sudo apt-get install git
git clone https://github.com/foxy82/pi-usb-gadget-controller.git

Install USB Gadget

Setup the pi so that it will behave as a USB Gadget.

cd ~/pi-usb-gadget-controller
./install_usb_gadget.sh

Install the app

Get the required packages first

sudo apt-get install python3 python3-pip

From pypi

sudo pip3 install pi_usb_gadget_controller

From source

cd ~/pi-usb-gadget-controller
sudo pip3 install .

Running

The above will install anm executable called UsbGadgetController. Running this will start a server on the default settings - you will need to run as sudo to access the USB gadget device or setup permissions to access it as a regular user.

$ sudo UsbGadgetController

There are some options that can be set

$ UsbGadgetController -h
usage: UsbGadgetController [-h] [--device DEVICE] [--web_port WEB_PORT] [--socket_port SOCKET_PORT]
                              [--logging {DEBUG,INFO,WARNING,ERROR}]

Send commands to a USB Gadget

optional arguments:
  -h, --help            show this help message and exit
  --device DEVICE       The USB Gadget device. DEFAULTS to /dev/hidg0
  --web_port WEB_PORT   The port to start the web_port on. DEFAULTS to 8080. NOTE if you specify a port here you also need
                        to spcify a --socket_port otherwise the socket port won't be opened
  --socket_port SOCKET_PORT
                        The port to start the socket server on. DEFAULTS to 8888. NOTE if you specify a port here you also
                        need to spcify a --web_port otherwise the web port won't be opened
  --logging {DEBUG,INFO,WARNING,ERROR}
                        The logging level to use. DEFAULTS to INFO

Install as a service (optional)

You can install the server as a service to run on start up:

cd ~/pi-usb-gadget-controller
sudo ./install_service.sh

This will use the default options. To change the options edit ~/pi-usb-gadget-controller/usb_gadget_controller.service and edit the ExecStart line then run ./install_service.sh (first install) or ./update_service.sh (updating)

Connect your pi

Shutdown the pi and then connect it to the device to be controlled using a data usb cable and using the data usb port on the Pi Zero (the one nearest the HDMI port on Zero W and Zero W2)

Usage

This app provides several ways to receive commands and currently supports the following:

• UP
• DOWN
• LEFT
• RIGHT
• SELECT
• HOME
• BACK
• PLAY
• MUTE

Socket interface

A socket interface is provided on port 8888 (by default).

It will accept commands in the format:

<key_state>|<key>\n

Where key_state is one of:

• down - Key has been pressed down
• up - Key has been released
• hold - Key is being held
• press - Key was pressed and released

key is one of the commands listed under Usage above.

e.g. example commands.

down|SELECT\n
up|SELECT\n
press|HOME\n

Websocket interface

A websocket interface is provided at http://ip:8080/ws it will take the commands in uppercase e.g. UP, DOWN

Rest API

A REST API is provided by doing a GET at http://ip:8080/rest/ where command is the key to send e.g. UP, DOWN

GET Requests

You can also do plain GET requests to http://ip:8080/get/ where command is the key to send e.g. UP, DOWN. This call will provide a redirect to a web page (see below)

Web Page

The app also provides 3 web pages with remote buttons to click and send commands:

• http://ip:8080 - is a web page using web socket for communication - it should be the fastest to use
• http://ip:8080/js - is a web page that uses JavaScript to make REST calls in the background - I have sometimes seen Chrome take up to 1+ seconds to actually send the command so WebSocket is prefered if you can use that.
• http://ip:8080/get - Sends GET requests and reloads the page on every click. Likely to be slow but will work if you don't want to use JavaScript or WebSockets.

Update

This is a work in progress so there might be times when updating is more complex. However you can try running ./update.sh from the root of the git repo.

Uninstall

The best bet is to just write a brand new OS onto the SD card however if you do need to remove...

cd ~/pi-usb-gadget-controller
sudo ./uninstall_service.sh # Only if you installed this as a service
sudo ./uninstall_usb_gadget.sh # Follow the additional instructions
sudo pip uninstall pi_usb_gadget_controller

Roadmap

Things i'm working on for this:

• V2 of the API to allow pressing and holding (in v 0.3.0)
• V3 of the API to allow keyboard keys to be sent.
• V4 of the API to allow mouse events (possibility if I decide I need this)
• A seperate app which will take input from a 2.4 GHz USB remote and transmit it to this app(in progress)
• Using a Pulse Eight USB CEC Adapter to take CEC commands and send it to this app.
• Use protobuffers to make it even more responsive (not needed at the moment)
• Moon shot - can we add a way for a mic to send us audio data so that we could do a voice search?

Useful links

Links that helped me come up with this solution

• Tutorial here on how to use the pi zero as a usb gadget - [https://www.isticktoit.net/?p=1383]
• Tutorial for someone doing volume control: https://www.ekwbtblog.com/entry/2019/01/31/000000
• Two tutorials on the report descriptor: [https://notes.iopush.net/blog/2016/custom-usb-hid-device-descriptor-media-keyboard/] and [https://eleccelerator.com/tutorial-about-usb-hid-report-descriptors/]
• Tool to decode the report descriptor: [https://eleccelerator.com/usbdescreqparser/] (need to replace \x with space for the tool)
• To find keycodes: [https://www.usb.org/hid] document is titled "HID Usage Tables 1.22" we need section 15 "Consumer Control"