Kev’s Blog – Page 160 – Kev's Development Toolbox

April 10, 2016

Scheduling scripts to run at boot on Raspbian (Raspberry Pi)

There’s always a dozen ways to do anything on Linux, and I was looking for a quick and easy way to run a script at startup on Raspbian on a Raspberry Pi.

I found this post:

http://raspberrypi.stackexchange.com/questions/8734/execute-script-on-start-up

which has a number of good suggestions, but the quickest and easiest approach is probably to add a @reboot entry to crontab, as suggested in this post here.

April 10, 2016

Amateur Radio related uses for your Raspberry Pi

Here’s a collection of Amateur Radio and other general radio related possible uses and ideas for using a Raspberry Pi. Some of these ideas could be used in connection with each other, or just solo.

This list is a collection of ideas for the basis of an upcoming presentation; more on that later. Right now, a collection of links for reference.

Simple:

as a simple/cheap Logging computer:
- CQRLog: https://www.cqrlog.com
- KLog: http://jaime.robles.es/klog/klog-intro/

Easy:

ADS-B aircraft transponder receiver (http://www.rtl-sdr.com/adsb-aircraft-radar-with-rtl-sdr/)

Slightly more involved:

APRS tracker (mobile APRS – ping beacon packets with location)
Software Defined Radio using RTL USB dongle and rtl-sdr (https://www.kevinhooke.com/2014/07/26/installing-rtl-sdr-and-dump1090-on-a-raspberry-pi-to-receive-ads-b-signals/)
CW progation beacon transmitter (http://hackaday.com/2013/01/25/raspberry-pi-used-as-a-beacon-transmitter/)
APRS i-gate (internet gateway for APRS data)
WSPR transmitter / WspryPi / TAPR Whispering Raspberries QRP Tx Shield

More involved:

Soundcard based Packet Packet TNC, using Direwolf: https://github.com/wb2osz/direwolf
Hardware Packet Radio using a TNC-Pi add on board
RadWav SDR transceiver add-on board $150: http://www.radwav.com/index.html
QTSDR – SDR transceiver (https://github.com/ha7ilm/qtcsdr)

Android Studio – useful notes (1)

Having worked for years with Eclipse (and some time with Netbeans), I have to admit that using Android Studio (based on InteliJ) I’m fining harder that what it should be. Where’s all my key shortcut combinations!

Whenever I use Netbeans, I use the Eclipse keymappings option in the settings, so I don’t have to remember any new key shortcuts. I’m not sure if Android Studio/IntelliJ has this option as well, but in the meantime, here’s some notes for useful things to remember.

Organize Imports (Eclipse: shift-Ctrl-O) / Optimize Imports: Ctrl-Opt-O

Jump to definition (Eclipse: F3) : Opt-Cmd-B

Fix error with popup suggestion: Opt-Return

Other useful Android development related posts:

http://stackoverflow.com/questions/17252870/how-to-show-compilation-errors-in-android-studio

http://stackoverflow.com/questions/2364811/how-do-i-write-outputs-to-the-log-in-android

March 28, 2016

Migrating Eclipse ADT Android project to Android Studio

It’s been a couple of years since I’ve done any Android development. In the meantime I was aware that Android Studio was coming along, but apparently now Eclipse and the ADT plugins are no longer supported, so time to migrate source from some existing apps I was working on to Android Studio.

First issue: remove paths from .classpath and project.properties files otherwise ADT library references are not resolved on import.

Next issue: “Unsupported Gradle DSL method found: ‘compile()’!” – luckily this issue and the solution is described exactly here. This is my first experience with Gradle too, so got some more learning to do 🙂