Bits and Pixels

If you are like me, then you might have a few machines around the house, or the office, into which you need to SSH frequently. Over time I accumulated a few ways to make this experience more convenient, without sacrificing security and I wanted to share these here: Specify the login user You might log into your SSH servers with usernames that are not the same as the one you use on your local system, the client. For example, your username might be john but you want to log into a raspberry pi server using the pi username. Now typically you would need to specify that username in the command line, e.g.: ssh pi@192.168.0.100 However, using ~/.ssh/config you can set which username should be used if no other one is specified, e.g.: Host 192.168.0.100 User pi Now you can simply say: ssh 192.168.0.100 You will be logging in as “pi”, unless you explicitly specify a different username. Give your stations a name This might be obvious, but typing IP addresses can be tedious and...

While I am adding more and more nodes to my custom Raspberry Pi based home automation system (more on that in future posts), I've seen most nodes having a pretty stable wireless connection. The Pi in my garage that is controlling the motorized garage doors for example has an uptime of about 500 days now without any issues. However, recently one of the Pi's connection became a bit flaky. The setup: A Raspberry Pi 2 Model B with an Edimax Wifi USB dongle. I am using these dongles for most of my Raspberry Pi devices, and had no issues. When researching (and by that, I mean googling ;) ) I found a surprising number of topics where people report having issues with the Pi not reconnecting when a Wifi connection is dropped. One solution I found involved rebooting the Pi when it notices that it has lost Internet connection. I find that a little bit drastic, but maybe something that can be done if all else fails. However, I also do not want to have all my Raspberry Pi devices i...

[Update on July 28th 2006] I have updated the post to reflect that CrashPlan 4.7.0 still works the same way as well as adding instructions for running the UI on MacOS/OSX Motivation I currently have a Synology DS212 (discontinued, but similar to more current  DS213 ), which works fine, but I wanted to have another backup of the data on it off-site, meaning not in my house. A few years ago I got myself a CrashPlan subscription and have since used to to back up my personal and my families data from multiple machines. Ideally I would like to run the CrashPlan software on my NAS, but the DS212 is not powerful enough to handle the Java-based CrashPlan client. Since I anyway already have a Raspberry Pi 2 Model B set up as a home server (I am running a custom home automation server and some other servers on it), I thought it would be great to add the CrashPlan client to it. Getting the CrashPlan headless client running on a Raspberry Pi is luckily possible, but there are a few ...

Background I am currently working on a project where I want to deploy small battery powered ATtiny based modules to track a few things and to communicate back to an Arduino or Raspberry PI. While I was first trying to use the Virtual Wire library , I found out it couldn't handle the ATtiny85 that I was operating at 1 MHz. The reason for this is that it has a different timing from chips that run at regular speeds, like the Arduino itself. Luckily there is an alternative in form of the Manchester Encoding library for Arduino . It works not just with the typical Arduino chips but also with various ATtiny variants. The only problem was that my Arduino IDE setup I had in place did not work with this library. In the following I will outline what the issue was and how I got around fixing it. My original ATtiny85 setup When I started out coding for the ATtiny85 I used sparkfun's excellent tutorial on how to set-up the Arduino environment to compile and upload ATtiny progra...

So I had this router for quite a while. I bought the EA2700 when I moved to the US, without doing much research. That was a mistake. I had a bunch of the famous WRT54GL routers before and was super happy with them, mainly due to the flexibility of installing an alternative OS on it, which unleashes a lot more power and functionality. However, the WRT54GL was just too dated in 2012, so I decided to get a newer model and got the Linksys Cisco EA2700. I don't want to go into too many details, but this was a pretty bad decision. The software is just really bad. Almost no functionality and on top they tried to put some 'cloud-connection' stuff that is not only unnecessary, but counter productive. They tried to market it as a "Smart Router".  A bit later I bought myself a TP-Link  TL-WR1043ND  and have been using it ever since. However,  today I found the (now old) EA2700 in a moving box. This inspired me to check the interwebs for the current status of DD...

Today I releases a couple of updates to my website. In order to test a few new features, I completely re-did the UI for the pictures. When you go there now you will see some polaroid-style photos. I was inspired by this post from the guys at ZURB. The albums view now shows some seemingly randomly positioned photos with a custom text that looks like hand-writing. I used the Google Web Font API for this. While being at it I also replaces all the head graphics with actual fonts. This reduces the number of requests made to fetch the data and the total amount of bytes loaded. In the next weeks I will try to roll-out some more features to the site. I plan to overhaul the portal page a bit and to optimize performance even more. By the way, you can now also reach this site at s13g.com :)

This week I've got a new toy: The Nikon D7000. Today I had a chance to test it for the first time. I am with my folks in Germany over the weekend and the weather is gorgeous. One of the great new features of the D7000 is that it can shoot HD video at 1080p and 24fps with auto-focus enabled throughout the shoot. I didn't have a camera that could shoot HD video before, except for my recently purchased Canon S95, which "only" shoot 720p. After some tests in the garden using flowers and fishes as my subjects I have mixed feelings, although I am mostly positive: The picture quality is stunning. Especially when watching the footage on a big 1080p screen. The DSLR lenses enable you to shoot with shallow depth of field which enables some quite professional looking shots. So what's the downside you might ask: Although the D7000 is able to focus throughout the shoot, the focusing technique used is not very good. The contrast detection mechanism forces the camera to focus in...

It's been a while since I wrote by last blog post. I've decided that it's time get the dust of this blog and to throw a new entry out. And again I hope, that this time I might be able to keep some more posts coming. Anyway, on to the actual topic of this post: I just released the source code of an application I worked on in my 20% time at Google. I called in PicView. It's a photo viewer application for Android. What can it do? It can download and show you photos from Google Picasa users. When you start up the application you can enter a Picasa user name, such as "saschah", which is mine. You will be presented with a list of albums of that user. A tap on the album will show you thumbnails of all the photos in that album. A tap on one of those - you guessed it - will show you the photo full screen. In full screen mode you can tap on the left or right-hand side of the photo to go back and forth the current album. The app is also caching heavily. Every download ph...