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PySPARC

PySPARC is a data acquisition system for the HiSPARC experiment, implemented in Python. Ramon Kleiss came up with the excellent name.

Please note that this repository was, at first, by no means intended as a replacement for the LabVIEW DAQ we currently have in operation. It was merely intended as a test bed. Later, work was started on a MuonLab application. This was done to be able to remote control a running muonlab experiment. An event display is possible with an HTTP interface.

Currently, we're looking into replacing our LabVIEW / Windows PC setup with a Raspberry Pi running PySPARC.

Prerequisites

I like the fact that we do not depend on FTDI drivers or closed-source libraries. We were using PyFTDI for HiSPARC III, but were running into strange problems. Pylibftdi / libftdi is proving to be a more stable combination.

Status

Alpha, but getting there.

Outlook

At the time of this writing (late 2017), there is renewed activity. We're testing this code on a few Raspberry Pi's with the goal of maybe replacing our old Windows PC's. They are a pain to maintain. The new effort focuses on adding support for primary/secondary combinations.

I (DF) was also planning on using this code to work out an event display and teaching materials for high school students. This will focus on the muon lifetime experiment. However, there already exists a LabVIEW interface and a new LabVIEW interface is in development for driving the Muonlab III hardware. This is not a priority anymore.

Updating the Raspberry Pi's

We use Ansible to keep all Raspberry Pi's up to date. Run the Ansible commands from the directory containing the ansible.cfg file. That is, the project root directory.

To update all machines (dev and production), run:

$ ansible-playbook provisioning/playbook.yml

To update only the machines in the dev group, run:

$ ansible-playbook provisioning/playbook.yml -l dev

Running isolated commands on the Raspberry Pi's

You can use Ansible to connect to a raspberry pi and run a command. Like so:

$ ansible \* -a "supervisorctl status"

The \* selects all machines. To limit the command to dev boxes, run:

$ ansible dev -a "supervisorctl status"

Vagrant development box

We have created a vagrant development box for testing. To use it, first install vagrant (https://www.vagrantup.com). For MacOS:

$ brew cask install vagrant

After installing vagrant, install the Virtualbox Guest plugin:

$ vagrant plugin install vagrant-vbguest

To start up the vagrant box:

$ vagrant up

The ansible playbooks and inventory include the vagrant box.

Creating the disk image for provisioning a Raspberry Pi

Perform the following steps:

  1. Download the latest raspbian image from http://www.raspberrypi.org/downloads/ and rename it to pysparc.img. Place the image in the root of this repository, which makes it available to the vagrant VM. Unfortunately, it is not possible to use a Mac to have read/write access to the ext4 filesystem in the image. Note that we're not using the image as a VM! We're using the pre-existing vagrant VM to access the image file.

  2. Download the VPN certificate for the host newpi and place the certificate in the root of this repository as vpncert.zip.

  3. Enter the VM using:

    $ vagrant ssh

  4. Because the image is a full disk image containing partitions, it is slightly nontrivial. Setting up the disk image involves some work, as well. We've created a script which takes care of everything:

    $ sh /vagrant/provisioning/provision_image.sh

    You can now use this image for multiple installs.

Writing the disk image

In a shell, back on your Mac:

$ diskutil list
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *8.0 GB     disk1
   1:             Windows_FAT_32 boot                    58.7 MB    disk1s1
   2:                      Linux                         3.2 GB     disk1s2
$ diskutil unmountdisk disk1
$ sudo dd if=pysparc.img of=/dev/rdisk1 bs=1m
$ diskutil eject disk1

Provisioning the new system

Once the device has booted, it will install OpenVPN, unzip the certificates and connect to the HiSPARC VPN network, as newpi. Make sure that you only boot one new device at a time, since otherwise multiple devices will connect as newpi , resulting in VPN disconnects. You can simply logon using SSH, download the final certificate, unzip it and restart OpenVPN:

$ cd /etc/openvpn
$ sudo unzip <path_to_certificate>
<choose overwrite all>
$ sudo systemctl restart openvpn

The connection will be immediately dropped, but can be restored by connecting using the new hostname. Add the new host to the Ansible inventory file and run the playbook.

Troubleshooting

Run command across all pysparc installations:

(localhost) $ ansible pysparc -a "<insert command here>"

Query the NTP daemon:

$ ntpq -p

Scan for filtered NTP port:

$ sudo nmap -PN -sU -p ntp time.apple.com