Tag: raspberry pi

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Enabling serial tty login to a Raspberry Pi

Depending on what Raspbian version you are running on your Pi, the approach for enabling a serial tty login via a VT terminal differs, but on current/recent versions you can enable by enabling and starting this systemd service (steps from this post, and here):

sudo systemctl enable serial-getty@ttyUSB0.service

and then:

sudo systemctl start serial-getty@ttyUSB0.service

This assumes you are using a USB serial dongle and that it’s connected as /dev/ttyUSB0. You can check by doing a ‘ls /dev/ttyUSB*’ before you connect your USB serial adapter and after to check what device your USB dongle appears as.

If you’re running an older version of Raspbian not using systemd, you can add a line to /etc/inittab to initialize getty as described here.

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Packet Radio: ax25 node logon message: updating for a cleaner menu

After logging on to an ax25 node, you’re shown a message like this:

DAVBBS:KK6DCT-6 Welcome to KK6DCT-6 network node

Type ? for a list of commands. help <commandname> gives a description
of the named command.

--

@kk6dct-6 20:52:01>

This is what is shown by my node that I’m currently setting up. I’d like to show a list of the apps I currently have configured. You can see the configured commands by entering a ? as the message tells you, but the formatting is not ideal, especially as I’m adding more apps and this list is getting cluttered. This is what the ‘?’ command shows for my currently configured apps:

@kk6dct-6 20:52:01> ?
DAVBBS:KK6DCT-6 Commands:
?, Advent, Bye, Connect, Escape, Finger, Help, HItchhikers, HOst
Info, Links, Mheard, NLinks, Nodes, PIng, Ports, Routes, Status
TAlk, Telnet, TIme, Users, W1-WeatherDavisCA, W2-Weather5DaysDavisCA
W3-WeatherForCity, W4-Weather5DaysForCity, Z1-Zork1, Z2-Zork2
Z3-Zork3, ZConnect, ZTelnet

When you logon, the first part of the welcome message that’s displayed is configured in /etc/ax25/node.motd (message of the day). Editing this file I can now more cleanly format the menu (and I might come back and change some of the names of the apps to make the menu options clearer later) :

DAVBBS:KK6DCT-6 Welcome to KK6DCT-6 network node
  W1		- Weather in Davis, CA
  W2		- 5 day weather forecast: Davis, CA
  W3		- Weather in specified city
  W4		- 5 day weather forecast for specified city
  Advent	- Adventure / Colossal Cove
  Z1		- Zork I
  Z2		- Zork II
  Z3		- Zork III
  
Type ? for a list of commands. help <commandname> gives a description
of the named command.

--

Much better!

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Upgrading cmake on Raspbian Jessie

Trying to build and install rtl-sdr from source I got this error on a Raspberry Pi 1 running Jessie:

$ cmake ../

CMake Error at CMakeLists.txt:22 (cmake_minimum_required):
CMake 3.7.2 or higher is required.  You are running version 3.6.2

Doing an ‘apt-get update’ and ‘apt-get upgrade’ is not picking up a more recent version, so following the steps here, I downloaded the required 3.7.2 version from source and followed the steps to build it: http://osdevlab.blogspot.com/2015/12/how-to-install-latest-cmake-for.html

I downloaded a .tar for the 3.7.2 version from:

https://cmake.org/files/v3.7

The build look over 2 hours, but completed successfully, and now I’m able to build rtl-sdr.

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Retrieving ADS-B transponder data from dump1090

dump1090 is probably the goto solution for receiving ADS-B transponder signals from planes flying overhead because

a) it runs with a cheap rtlsdr USB dongle (more info on dongles here)

b) runs on a cheap $35 Raspberry Pi

I’ve always wondered how it would be possible to get data out of dump1090 to use within other apps. It provides a data feed on port 30003 that is relatively easy to capture by using a util like netcat. If you have another app to receive/parse/process the data, this is as easy as:

nc ip-of-pi 30003 | app-to-parse-data

I have a project ‘in-flight’ right now using this approach… more updates later.

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