# mpdlistenpy

This python script is supposed to run on a rpi and does the following :

 * Relay trigger : Watches a MPD instance for play/pause/stop states and activates a relay via GPIOs accordingly ; the usecase for this is powering on/off a pair of speakers only when something is running.  
 * OLED display : Drives a 0.96" OLED display (ssd1306) to display MPD status (volume, current artist, album, title...)  
 * Button input : watches GPIOs for button input ; I'm using 5 push buttons for controlling playback (previous, next, toggle playback, stop, menu) or browse the database and add stuff to the playlist.  
 * Rotary encoder for volume control.  

## Setup

### Software

1. Install the latest **light** version of Raspberry Pi OS and run it on the RPI model of your choice.
2. Install the following dependencies (these are for mpd, the python script and filesystem handling):  
  ```
  sudo apt install --no-install-recommends --no-install-suggests mpd gvfs-fuse gvfs-backends gvfs libglib2.0-bin python3-musicpd  python3-luma.oled i2c-tools python3-pil libjpeg-dev zlib1g-dev libfreetype6-dev liblcms2-dev libopenjp2-7 libtiff5-dev exfat-fuse
  ```
3. Configure '~/.config/mpd/mpd.conf' as you please and enable mpd systemd unit :  
  ```
  systemctl --user --full enable mpd
  ```
4. See [Installing the systemd service](#installing-the-systemd-service) for installing the mpdlistenpy systemd service and start/enable it.  
5. See [Automounting Samba shares on startup](#automounting-samba-shares-on-startup) for setting up an automount service and start/enable it.  

### Hardware

#### Overall GPIOs usage

| FUNCTION | GPIO # |
| ---    | ---   |
| OLED | GND, 3.3V, 2(SDA), 3(SCL) |
| 5 BUTTONS | GND, 7, 8, 9, 11, 25 |
| POTENTIOMETER | GND, 3.3V, 23 |
| ROTARY ENCODER | GND, 3V3, 27, 22 |

You can check these here : [https://pinout.xyz/](https://pinout.xyz/)  

#### Oled screen

Using the SSD1306 OLED screen involves a few steps described here :

[https://luma-oled.readthedocs.io/en/latest/hardware.html](https://luma-oled.readthedocs.io/en/latest/hardware.html)

and here :

[https://luma-oled.readthedocs.io/en/latest/software.html](https://luma-oled.readthedocs.io/en/latest/software.html)

Once you've gone through these steps, you should be good to go.  

#### Relay circuit

We're using the circuit described on projects-raspberry.com :

##### Components

 * 5V DC coil relay
 * BC337 NPN transistor
 * 1N4002 [diode](https://en.wikipedia.org/wiki/1N400x_general-purpose_diodes)
 * 1KΩ resistor

##### Diagram 

![https://web.archive.org/web/20240217011938/https://projects-raspberry.com/raspberry-pi-driving-a-relay-using-gpio/](https://web.archive.org/web/20240217011938im_/https://projects-raspberry.com/wp-content/uploads/2015/04/Raspberry-Pi-%E2%80%93-Driving-a-Relay-using-GPIO2.jpg)

*source: [https://projects-raspberry.com/raspberry-pi-driving-a-relay-using-gpio/](https://web.archive.org/web/20240217011938/https://projects-raspberry.com/raspberry-pi-driving-a-relay-using-gpio/)*

#### Buttons circuit

Dead simple way described here, using a common GND, and 1 GPIO/button : 

[http://razzpisampler.oreilly.com/ch07.html](https://web.archive.org/web/20240121074741/http://razzpisampler.oreilly.com/ch07.html)

The only difference is the addition of a resistor on the GND rail.  

If you're short on GPIOs, there is a way to use a single GPIO for multiple buttons based on resistance described here : 

[https://www.instructables.com/RaspberryPi-Multiple-Buttons-On-One-Digital-Pin/](https://www.instructables.com/RaspberryPi-Multiple-Buttons-On-One-Digital-Pin/)  

#### Rotary encoder circuit

Using [https://github.com/Tr3m/rpi-rotary-encoder](https://github.com/Tr3m/rpi-rotary-encoder), we can use a 3-pins rotary encoder to control volume.  

##### Wiring

| ENCODER | RPI GPIO # |
| ---    | ---   |
| GND | GND |
| + | 3V3 |
| CLK | 27 |
| DT | 22 |

## Optional steps 

### Installing the systemd service

 * Copy the provided service file 'mpdlistenpy.service' to '~/.config/systemd/user/mpdlistenpy.service'.  
 * Update, enable and start the service as a user :
 
```
 # If you need to edit the path to the script (should be in ~/mpdlisten by default)
 # systemctl --user --full edit mpdlistenpy.service
 systemctl --user daemon-reload
 systemctl --user enable mpdlistenpy.service
 systemctl --user start mpdlistenpy.service
```

### Automounting Samba shares on startup

If you want to setup a systemd service that mounts smb shares on startup, follow these instructions :

[Automount SMB shares on startup](https://forge.chapril.org/ABelliqueux/smbautomount)

*source :* [https://root.nix.dk/en/utility-scripts/mount-samba-share-as-user](https://root.nix.dk/en/utility-scripts/mount-samba-share-as-user)

### Automounting USB

[https://gist.github.com/zebrajaeger/168341df88abb6caaea5a029a2117925](https://gist.github.com/zebrajaeger/168341df88abb6caaea5a029a2117925)