Topic: Computer

Hardware, software & hacks

Controlling a HDSP-2112

The HDSP2112 is a module with a LED matrix display which displays 8 characters with 5×7 LEDs each. Due to the high power requirement of more than 2 watts this display is not suitable for mobile devices. The operating voltage is 5 volts and it will be controlled using a 8 bit wide data bus and a 5 bit wide address bus.

I already experimented with this in 2013, however I stopped working on that and did not have a working setup ever.

This time I was more persistent – and it worked :-).

HDSP-2112, Test mit Raspberry Pi

More about this along with a thorough documentation on the project page.

By the way – about USB controllers

My PC is built into a tower case from Chieftec. This case offers also external ports for USB 3 among other things. Internally, these ports are connected to the mainboard.

However, I also installed an internal memory card reader from Chieftec, which also uses USB 3 and offers a 4× USB hub. This means that the only internal USB 3 port on the mainboard is occupied. In order to be able to use the external USB connections, I bought an additional controller for PCI-Express, which offers two external USB connections and two more internal connections. The connections in the housing can also be supplied via this.

So far so good – but there was a strange effect when I tried to use a Velleman K8055N: as soon as the connection was established in the software, the software stopped working. This effect did not occur using the connections of the mainboard itself. The USB connections of the memory card reader were not a problem either.

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Signal wants to integrate “Mobile Coin”

I advertised the use of Signal already in 2019 and was quite happy that many of my contacts changed to Signal as well when WhatsApp announced a mandatory change in their terms of use at the beginning of 2021.

Now Signal decided to integrate the crypto currency “Mobile Coin”. Moxie Marlinspike works as a paid consultant for Mobile Coin, so this is not really a surprise. Nevertheless I consider this questionable and I am not alone with this impression.

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OnlyOffice in Nextcloud – the current status

I recently reported hastily that OnlyOffice in Nextcloud would generally no longer work properly.

However, this is generally not correct and I did premature conclusions for some points. Ascensio System also got in touch with me and did everything possible to help me with my problems – thank you!

I removed the original post because it was based on incorrect assumptions.

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“Retro” High End

Recently a good friend of mine gave me a used Intel Xeon E5-1650 v2 which he didn’t need any longer as a gift. According to the data of Intel this model was already introduced in the third quarter of 2013 and is therefore 7 years old as of August 2020.

Calling this “retro” may be a bit exaggerated – but it is a valid question if using such an old processor still makes sens in the year 2020. Current models provide more performance while also often using less power. In addition memory modules with DDR4 provide a higher throughput as well.

On the other hand my old PC is still mostly based on the hardware with a Xeon E3 which I bought already in 2014 and which got equipped with SSDs as mass storage and a new graphics card running a 4K display. Despite its age it is still usable quite well. Moving to the Xeon E5 would be an easy upgrade since I only would have to change the mainboard and the CPU cooler. The existing RAM modules could be used unchanged.

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Nextcloud Talk: “High Performance Backend” now Open Source

Nextcloud Talk is an extension for Nextcloud that enables chats as well as video conferencing. A decent browser and a webcam are sufficient to use that. You can also use an app for Android or iOS.

With a few simultaneous connections this usually works quite well if you pay attention to a few points, such as using a server for STUN/TURN like coturn (I will write a separate article about this).

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USB 3.0 in the year 2020

In the year 2011 I wrote about USB 3.0 for the first time. A few years later again (USB 3.0 today). Meanwhile it is 2020 and a current benchmark of a SanDisk Extreme Pro with 128 GB. To have comparable values again with “HD Tune” but this time with Windows 10.

The hardware used for the test is still the same mainboard which I’ve been using since 2014.

Looking back the values of earlier tests which show the impressive development of about 20 year:

Storage media Read speed
M-Sys DiskOnKey 128 MB (USB 1.1) 0.9 MB/s
Sony 8 GB (USB 2.0) 15.2 MB/s
Verbatim Store N Go 16 GB (USB 3.0) 122.4 MB/s
SanDisk Extreme Pro 128 GB (USB 3.0) 209.6 MB/s

Spamfilter and DKIM with rspamd

Recently a major update of the server enviroment was needed on which I also run a mail server. I took this as an opportunity to try rspamd as alternative to the combination of SpamAssassin and amavisd-new and can fully recommend this.

Main features of rspamd:

  • Web UI with status information and for easy configuration changes.
  • Up to 10× faster than SpamAssassin (also see the explanation at rspamd).
  • Direct integration as milter in Postfix which allows to scan e-mail during delivery so they can actively rejected or delayed using greylisting if needed.
  • Optional DKIM signatures for outgoing e-mail.

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