That was a really nice Sunday… 🙂
At work we have a KVM over IP switch from Inter-Tech, a KVM IP-KVM101. It is really a small and versatile device that, in combination with 16-port KVM switches, allows us to control a complete rack with test hardware.
The KVM switch provides a web interface with a Java Web Start application for remote access. But the latest browser security updates disabled and removed the Java Web Start support . This move was announced quite some time ago (Oracle White Paper). Still, the vendor of the KVM switch, Inter-Tech, was not able to provide a valuable solution to cope with this problem.
After a bit of Googling I found an Amazon review about this particular KVM switch where the reviewer stated to have installed the firmware from another brand, the LINDY KVM over IP Switch. The LINDY switch looks identical (besides a different sticker) and – even better – their latest firmware provides a VNC server. This would allow us a browser and even operating system independent access to the KVM.
The 80’s called: they want their audio back…
That’s what happens when you’re drinking a few beers and being in a nostalgic mood: Already over a year ago I had designed a generic Covox Breakout Board (Wikipedia link) based on an
old well established design.
The whole design is based on two TTL ICs (74HCT373 and 74HCT164) and an R-2R resistor ladder (7.5k and 15k Ohm). The result is a simple DAC with 8 bit parallel and serial input and a few control pins. I’ve uploaded the PCB (back then I still used Eagle Cad) and the Gerber files to my Github Covox Repository.
Sure, I could have taken a cheap audio DAC, address it for example via SPI, and let the dedicated chip do all the heavy lifting. But that would not have been half of the fun of designing the board and (bit)banging the audio signal… 😉
The design is pretty generic and when I built it I thought I could use it in combination with a Sharp PC to generate audio output. I started with a few lines of code, but in the mean time other private tasks became more important. So I’ve reduced my testing of the Covox card to connecting it to an Arduino board and output simple (square and saw tooth) waveforms on my oscilloscope. Maybe if there is enough interest I will try to create a video with some mod-tracker like audio output…
Using spreadsheet files for data storage and exchange can lead to the
corruption and even loss of information — sometimes without noticing it immediately. I came across this one too often so I could not help but write a rather long post about this topic.
Sharing datasets with other researchers or collaboration partners is a vital part of the knowledge exchange in a community. This might happen in big scale in form of supplementary material along with publications or in small scale within research groups. In this post I do not want to focus on what is actually shared, but how. Because a crucial but commonly underestimated element when sharing datasets with others is the used data format. Continue reading
I literally wanted to start this post with “I literally hacked the PiDrive cable…” but I actually have sawn it instead. Duh!
I’m using quite a few Raspberry Pi boards as servers, gateways, etc. and recently started to ‘polish’ their design. Instead of hard drives hanging beside them with a bunch of loose cables I’ve started to buy WD PiDrive Cases and Cables to pack all of them into nice ‘little boxes’.
The PiDrive Cables are really neat: they are designed to be positioned between a Raspberry Pi, its power supply, and an USB hard drive. The cable is designed for USB 3.0 hard drives, but in one case (hah) I wanted to use an external USB 2.0 drive I had lying around. So without further ado I’ve removed the USB 3.0 extension of the connector with a saw. It looks crude but works perfect…
About a year ago (2016) Aliexpress decided to
cripple simplify their search engine. They’ve removed really useful search options and added (at least in my eyes) unnecessary ones.
These useful search options were removed from the search panel but they are still available as URL parameters. I’ve mainly written this post to document these missing options for my everyday searches — but I’m pretty sure others may find them useful as well.
|isUnitPrice||y||Show Price per Piece|
|minQuantity||value||Minimal Quantity in Lot|
|maxQuantity||value||Maximal Quantity in Lot|
|minPrice||value (e.g. 1.23)||Minimum Price|
|maxPrice||value (e.g. 9.87)||Maximum Price|
|isFavorite||y||Results with 4+ Rating|
|isFreeShip||y||Free Shipping only|
|shipFromCountry||cn/de/us/…||Country of Origin|
Especially the option isUnitPrice is helpful when searching for the best price per piece and not price per lot. I really cannot understand why this option is not available per default.
So when I’m searching for the lowest price per piece within a certain quantity range (here: 10 – 50 pieces) with free shipping I would add to the URL (Example Search):
Side Note: It also makes a difference which keywords you are using when searching. The following three searches will (at least the last time I’ve checked) give different results:
- “stm32f103c8t6 lqfp“
- “stm32f103c8t6 lqfp48“
- “stm32f103c8t6 lqfp-48“
So even slight variations can make a big difference. Unlike the search on eBay, the search on Alibaba and Aliexpress does not split up keywords into smaller ‘chunks’ which are used for searching.
2018-08-02: Updated the List of Search Options
TL/DR: Use extended partitions for Linux in a dual-boot setup with Windows 10 — otherwise you might not be able to boot after a Windows update.
A few days ago I had to fix a dual-boot setup consisting of a Windows 10 and a Linux (Ubuntu) system. After deploying the latest Windows 10 Anniversary Update neither Linux nor Windows was accessible anymore. Only the GRUB rescue prompt appeared:
error: unknown filesystem. Entering rescue mode... grub rescue>
GRUB wasn’t even able to manually boot into the Windows or Linux partition. Continue reading
I’ve started to rework my Raspberry Pi ‘dial-up’ interface. Instead of just handling my external VPN and SSH connections I’ve extended it to also function as an intermediate file server and Git repository (both via NFS+SSH). I’ve also inserted the Raspberry Pi into a new case and added a 1 TB 2,5″ drive. I think it can handle additional load so I plan to extend its capabilities to also serve as a RetroPie console.
By the way: the case and the connector cable between the drive and the Pi are both from WD Labs. The hard drive is not a PiDrive but a refurbished USB 3.0 1 TB disk (it was a recertified My Passport Ultra) before I’ve dismantled it. For me it was cheaper that way. If you’re looking for a similar setup and need an additional power supply and SD card maybe you should think about buying a Nextcloud Box (free shipping; handled by WD). You might not need to use its ‘cloud’ functionality but still get all hardware I’ve previously mentioned which I think is a pretty good bargain.