pd on raspberry pi

here is a quick tutorial on how to install and run puredata headless on a raspberry pi. the instructions assume you want to start with a new clean [raspbian] system image and do it all from scratch.
the instructions also assume you have a raspberry model b, an usb soundcard like terratec's aureon dual usb and an ethernet cable with internet access (just connect the cable to your router).
what you get after following the below tutorial is a sdcard with a pd patch that automatically starts when the pi is booted.

update 160109: also works great on a raspberrypi2 with 2015-11-21-raspbian-jessie.img

//--preparations:
* put the raspbian image (2014-12-24-wheezy-raspbian.img) onto a +4gb card (on osx it is easily done with PiFiller).
* insert the sdcard+ethernet+usbsoundcard and power up the rpi
* open the terminal application on your laptop and type...
$ ssh pi@raspberrypi.local #log in from laptop with pi/raspberry (see notes below if fail)

//--setup
$ sudo raspi-config #run this on the rpi and do the following system configurations
* select expand filesystem
* change user password
* optionally lower the gpu memory under advanced / memory split
* select finish and reboot

$ ssh pi@raspberrypi.local #log in again from laptop
$ sudo apt-get update #on the rpi. check for new updates
$ sudo apt-get upgrade #update any old packages

//--test sound
$ lsusb #should list the usb soundcard
$ aplay -l #should also list the soundcard
$ sudo speaker-test -t sine -c 2 -Ddefault:CARD=Device #should sound if headphones connected. stop with ctrl+c
# note this assume that your usb soundcard name is Device - check what aplay and edit the CARD= in the line above if needed.

//--install pd
$ sudo apt-get install puredata #download and install puredata + required packages

//--test pd patches
copy the following two example pd patches (or download the attachments below) and save them on your laptop (here assume on the desktop). to copy pd patches just paste the cryptic text into a plain text editor and save with .pd file extension.

//--testsines.pd

#N canvas 1068 88 450 300 10;
#X obj 238 159 dac~;
#X obj 235 73 osc~ 400;
#X obj 289 73 osc~ 404;
#X msg 126 154 \; pd dsp 1;
#X obj 126 83 loadbang;
#X obj 126 123 del 100;
#X text 42 122 important ->;
#X obj 238 111 *~ 0.2;
#X obj 280 111 *~ 0.2;
#X connect 1 0 7 0;
#X connect 2 0 8 0;
#X connect 4 0 5 0;
#X connect 5 0 3 0;
#X connect 7 0 0 0;
#X connect 8 0 0 1;

//--testmic.pd

#N canvas 1068 88 450 300 10;
#X obj 238 230 dac~;
#X msg 126 154 \; pd dsp 1;
#X obj 126 83 loadbang;
#X obj 126 123 del 100;
#X text 42 122 important ->;
#X obj 238 24 adc~;
#X obj 238 53 delwrite~ del1 500;
#X obj 238 123 delread~ del1 500;
#X obj 259 80 delwrite~ del2 750;
#X obj 280 144 delread~ del2 750;
#X obj 238 182 *~ 0.2;
#X obj 280 182 *~ 0.2;
#X connect 2 0 3 0;
#X connect 3 0 1 0;
#X connect 5 0 6 0;
#X connect 5 1 8 0;
#X connect 7 0 10 0;
#X connect 9 0 11 0;
#X connect 10 0 0 0;
#X connect 11 0 0 1;

//--copy pd files to rpi
$ exit #log out from the rpi
# run the two lines below on your laptop to copy the two example patches to your rpi. (this is also how you can transfer more pd patches later on.)
$ scp ~/Desktop/testsines.pd pi@raspberrypi.local:/home/pi/
$ scp ~/Desktop/testmic.pd pi@raspberrypi.local:/home/pi/

//--run puredata
$ ssh pi@raspberrypi.local #log in from laptop again
$ pd -stderr -nogui -verbose -audiodev 4 testsines.pd #stop with ctrl+c
$ pd -stderr -nogui -verbose -audiodev 4 testmic.pd #stop with ctrl+c
# note: you will need to connect headphones or speakers for the first example to work. and some kind of audio input (e.g. electret mic or line-in from mp3 player) for the second example patch to work.

//--autostart
$ nano autostart.sh #creates a new file. copy the two lines below into this new file.

#!/bin/bash
pd -nogui -audiodev 4 /home/pi/testsines.pd

# save and exit with ctrl+o, return, ctrl+x
$ chmod +x autostart.sh #make the autostart.sh file executable
$ sudo crontab -e #and add at the end...

@reboot /bin/bash /home/pi/autostart.sh

# again save and exit with ctrl+o, return, ctrl+x
$ sudo reboot #restarts the rpi. after booting the sine tones patch should have started automatically.

//--stopping
$ ssh pi@raspberrypi.local #log in from laptop once more
$ sudo pkill pd #stop pd
$ sudo halt #turn off the rpi safely

//--notes
* if you cannot log in and you get ssh: Could not resolve hostname raspberrypi.local, you might need to replace raspberrypi.local with the exact ip address of the rpi (e.g. ssh pi@192.168.1.51). the exact address will vary and can be found in your router setup.
* note: if you get WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! then run the command $ ssh-keygen -R raspberrypi.local to reset the ssh key.
* when ready with everything and you have the correct pd patch autostarting you can [physically] lock the sd-card. this will put it in no-write mode and possibly prolong its life (specially if you cut the power without properly turning off the system with sudo halt)
* if you experience audio dropouts you might try the suggestions here... http://wiki.linuxaudio.org/wiki/raspberrypi. most important force usb1.1 and set cpu governor to performance mode.
* if you get ALSA output error Device or resource busy when trying to start pd, then delay the ';pd dsp 1' message in your pd patch with about 100 milliseconds.
* to remove the autostart just delete the file autostart.sh and go into cron again and remove the last line you added with sudo crontab -e

AttachmentSize
Binary Data testsines.pd370 bytes
Binary Data testmic.pd522 bytes