Tag: raspberry pi

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Notes from Raspberry Pi with Java 9 session – CON6210 – JavaOne 2016

A few interesting notes from the Java 9 Embedded on Raspberry Pi, session CON6210, presented by Stephen Chin.

Currently streaming live on YouTube: https://www.youtube.com/watch?v=v95y5CzvcZ4&feature=youtu.be

Full live stream schedule is here: https://community.oracle.com/docs/DOC-1005786

  • SE9 Embedded will be available in a ARM build for the Raspberry Pi
  • This ARM specific build will only be available for Pi 2 and 3 (not the original Pi 1 A/B and + models, as it’s been compiled for ARM Thumb-2 instructions, and these are only supported on Pi 2 ARM CPU and above
  • AWT, Swing and JavaFX will all be supported on SE9 Embedded on the Pi
  • Interesting side note about modular Jigsaw in SE9 – apparently the module file packaging and compression is moving away from zip based Jars, to another format that’s more efficient for class lookup/retrieval
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Winlink amateur radio email via paclink-unix on the Raspberry Pi

This is my second attempt to get a Winlink client (see here for a high level overview of Winlink) working on the Raspberry Pi. I first tried Pat /wl2k-go but it crashed (I created a ticket on github to followup), so for my second attempt I took a look at paclink-unix.

This site has a very detailed step by step install and config steps – follow exactly and pay attention to any errors 🙂 : http://bazaudi.com/plu/doku.php?id=plu:install_plu

A few additional notes:

  • wl2kax25 did not compile for me with the ax25 version that I previously had installed, possibly from apt-get from the default repos. Once I noticed this was missing I went back to the steps in the doc above and downloaded the ax25 packages from source, compiled, installed, rebuilt paclink and now I had the wl2kax25 app
  • Editing the /usr/local/etc/wl2k.conf file: the email= value is your local user email address on your local device, in this case on the Pi (e.g. for me, pi@localhost). This is used when wl2ktelnet/wl2kax25 retrieves incoming messages and it sends them to this user. If you see the wl2k app downloading messages but they’re not showing up in your inbox, check this.
  • Checking /var/log/mail.log is very useful to see what’s happening to your outbound and inbound messages!

The usage sequence is:

  • send outbound message with mail client, e.g. alpine
  • run wl2ktelnet to send over an internet connection if you have one
  • or, run wl2kax25 to send over your configured ax25 stack

The setup I got working is:

  • Raspberry Pi, with alpine (regular email client), direwolf (packet soundcard modem) and ax25 (to link paclink to direwolf)
  • Rigblaster Advantage USB soundcard, connected to an Icom 880

To send over vhf to my nearest Winlink gateway, I used:

  • wl2kax25 -a 1 -c KG6SJT-10 via KBERR

Where

-a 1 is port 1 defined in my /etc/ax25/axports

-c is the call of the Winlink gateway I’m connecting to, and I’m connecting via a packet digipeater, KBERR.

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Docker Swarm node set up with Docker 1.12 RC on Raspberry Pi

I’ve been following through the steps in this article to set up a Docker swarm cluster on a pair of Raspberry Pis. Most of the steps work as-is from Mac OS, but for a few steps there’s a couple of variations.

This is most likely going to be part 1 of a few posts as I work through and get this working.

For example, to copy your ssh key to the Pis, instead of:

ssh-copy-id pirate@pi3.local

… you can do (from tip here):

cat ~/.ssh/id_rsa.pub | ssh user@machine "mkdir ~/.ssh; cat >> ~/.ssh/authorized_keys"

To switch between remote hosts:

eval $(docker-machine env pi1)

where pi1 is the name of the remote host.

To switch back to the localhost (not entirely obvious but found the answer here):

eval "$(docker-machine env -u)"

After ‘swarm init’ and adding the other nodes to the cluster, ‘docker swarm ls’ lists the nodes in the cluster:

More to come in part 2:-)

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Configuring a static IP on HypriotOS for the Raspberry Pi

How you configure a static IP on the Pi changed between Wheezy and Jessie, and it seems on Hypriot’s prebuilt images for running Docker on the Pi, it’s a slight variation.

Edit /etc/network/interfaces.d/eth0, comment out the DHCP line:

iface eth0 inet dhcp

and add:

iface eth0 inet static
address your-static-ip
gateway your-gateway-ip
#google dns servers
domain_name_servers=8.8.8.8, 8.8.4.4

Done!

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