Category Archives: Networking

How to configure RealVNC on a Pi with 3.5” LCD

With the release of a new Raspbian version (2016-09-23) RealVNC have ported their VNC server and viewer applications to Pi, and they are now integrated with the system and PIXEL desktop. With raspi-config, one can enable start of RealVNC at boot time. This is particularly useful, if you’re running your Pi headless a (without monitor), but still want to access the LXDE desktop. RealVNC usually works out of the box, but …

35lcdtft… it doesn’t, when you connect a non-standard display. I recently upgraded one of my Raspberry Pi’s with a 3.5” LCD touch screen, which connects through the GPIO header and has a resolution of 320×480 pixels. Unfortunately, with the display attached, VNCviewer’s desktop size also shrinks to 340×480 pixels which is very inconvenient to read when it is displayed on a 1920×1080 HDMI monitor. Scaling of the window makes its contents very blurry.

However, with some special settings, one can circumvent this problem:

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How to enable USB OTG mode on a Pi Zero

Thanks to the Maker Faire Berlin on 1st and 2nd of October, I was able to purchase a Pi Zero board, which currently is out of stock  at most distributors. Indeed, it is a nice little board for experimenting with the GPIO header.

IMG_8215

In contrast to other Pi versions, it features a micro USB port, which is capable to connect in USB OTG mode (On-The-Go) to a host-PC. Thus, there is no need for a power supply and WiFi dongle, since communication with the host-PC is established through USB networking. This is especially useful if you want to use the Pi Zero in headless mode, for example in a classroom environment already equipped with desktop PCs and/or notebooks.

There are already other tutorials which describe how to enable USB OTG mode on a Pi Zero. However, I’ve been struggling with configuration of a fixed IP and internet/ network connection through USB on the Pi Zero. So here are some helpful instructions on how to achieve this:

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Using the ESP8266 module for the Internet of Things

About two years ago, a cheap five dollar microcontroller has been entering the maker scene, featuring b/g/n wireless LAN.  The ESP8266 is manufactured by a Chinese company, called Espressif Systems and became soon very popular as a building-block for home-automation and IoT projects.These modules were distributed on  Ebay, the Amazon Marketplace or AliExpress for a few dollars. However, communication with most of the ESP8266 modules requires an external USB-to-Serial-Adapter and a special procedure to bring the device into “flash-mode”, which can be cumbersome in some cases, especially for beginners. With the brand-new WeMos D1 Mini, the setup was significantly simplified, so that it is as easy to use as an Arduino UNO.

esp8266-12-e1452522744313-300x231

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CUPS server with rcswitch-pi

My laser printer is placed far away from my desk and automatically connects to my WLAN router when it is switched on. I do not use the printer frequently, so that it is idle most of the time. Recently, I started some experiments controlling the light of my aquarium using a 433 MHz remote switch, which worked like a charm. I thought that it would be nice to save some power by letting the printer start as soon as a new print job arrives to the printer. So here is how it works:

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Folder sharing with NFS

If you’re running out of space on your Pi’s SD memory card or want to share folders under Linux, you should consider using the Linux network file system (NFS). All you need to do is to install rpcbind, nfs-common and nfs-kernel-server on your Pi.

On a freshly installed you must enable the rpcbind service before you can start the nfs-kernel-server:

$ sudo update-rc.d rpcbind enable

The network file system is particularly useful if you want to merge folders across your home network which reside on different systems. In order to listen to my ogg/mp3 music collection I’ve attached a Raspberry Pi to the AUX input of my Hi-Fi equipment. The collection resides on a USB stick and can be accessed with the music player daemon (mpd) and Minion, so that I can use my smartphone as a remote. Another music collection resides on my AVM Fritz Box, which acts as a mediaserver and NAS.

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