This is a configurable Python service to run on Raspberry Pi.

raspi-gpio-mpdc runs a Python script as a service on Raspberry Pi. It uses the GPIO Zero package which allows selecting among various underlying pin factories. Tested with pigpio library only.

Various GPIO inputs connected to buttons and rotary encoders can be configured to trigger certain events to control a MPD/Mopidy server. For that purpose, python-mpd2 package is used as a MPD client interface.

• Mopidy with Mopidy-MPD extension (or another MPD server)
• pigpiod (or any other supported pin factory library)
• GPIO Zero
• python3-systemd
• python3-mpd / python-mpd2

Download raspi-gpio-mpdc via Code button or from Releases page (you most likely did already). Unzip the received file:

unzip raspi-gpio-mpdc-main.zip -d ~/raspi-gpio-mpdc

Configure the service by editing the file raspi-gpio-mpdc.conf according to your external hardware circuit set-up (see Configuration). Then simply run the script install in the script sub-folder. It will download and install the required packages, copy the files to their destinations, will register the service, and finally start it.

If you need to change the configuration after installation, you might use the script reconfigure after editing the source configuration file. This will stop the service, copy the changed configuration file to /etc folder (overwrites previous version!), and then start the service again.

If you downloaded a newer version of the service the script update will handle stop and start of the service, and will copy the new Python and service files. However, this will not update any underlying packages or services.

For uninstall, use the provided script uninstall.

The configuration is defined in the file raspi-gpio-mpdc.conf. Before installation, you will find the source file in the folder where you unzipped the package files. After installation, the active version is in /etc folder. It requires a section [GPIO] with one or more, but unique keys of the pattern ButtonN or RotEncN where N is replaced by an integer number. All pin numbers must be given in BCM format, not physical pin numbering!

1. The ButtonN key-value-pairs must be created based on this pattern:

   ButtonN = input_pin_number,up|dn|upex|dnex,press|release,trigger_event[,bouncetime_ms]

   input_pin_number

   The GPIO pin in BCM format to which a button is connected.

   up|dn|upex|dnex

   Selects the pull-up or pull-down resistor for the pin which can use Raspi internal ones, or external resistor provided by your circuit.

   press|release

   Determines the button event for triggering the MPD event, namely when button is pressed or released.

   trigger_event

   The MPD event to trigger. One of:

   • play_pause - toggle playback state between play and pause
   • play_stop - toggle playback state between play and stop
   • prev_track - select previous track
   • next_track - select next track
   • mute - toggle output state between mute and unmute
   • vol_up - increase output volume
   • vol_dn - decrease output volume
   • prev_src - switch to the previous source
   • next_src - switch to the next source

   bouncetime_ms

   (optional) Defines the time in milliseconds during which subsequent button events will be ignored. Default is 50ms.

   e.g.

   Button0 = 9,upex,press,mute,100

   configures pin GPIO9 as input expecting an external pull-up resistor, and acting when button is pressed with a bounce time of 100ms, to mute/unmute the output

2. The RotEncN key-value-pairs must be created based on this pattern:

   RotEncN = input_pin_A,input_pin_B,up|dn|upex|dnex,rot_ccw_event,rot_cw_event[,bouncetime_ms]

   input_pin_A,input_pin_B

   The pair of GPIO pins to which a rotary encoder is connected. The sequence of high-low-high transitions determines the rotation direction. (Remaining pins are usually connected to VCC, GND, and an optional button switch.)

   up|dn|upex|dnex

   Selects the type of pull resistors for the two pins which can use Raspi internal ones, or external resistors provided by your circuit or module.

   rot_ccw_event

   The event to trigger when the rotary encoder is turned counter-clockwise. Same as for buttons.

   rot_cw_event

   The event to trigger when the rotary encoder is turned clockwise. Same as for buttons.

   bouncetime_ms

   (optional) Defines the time in milliseconds during which subsequent encoder events will be ignored. Default is 20ms.

   e.g.

   RotEnc0 = 18,19,upex,vol_dn,vol_up

   configures pins GPIO18 and GPIO19 expecting a pair of external pull-up resistors, to act as inputs from a rotary encoder which turns volume down and up, respectively.