Minimal Setups

Tetris

Mon, 27 May 2024 00:00:00 +0000

Tetris - Hardware and Software

Update Amplifier (separate input circuitry per PSG, it appears, that a silent PSG has a DC level on its output which is summarized to the AC output of the working PSG, so two input circuits with individual couping capacitor):

Update of the power switch of the amplifier (at appears, that the small transistor couldn’t deliver enough current):

This Tetris implementation consists of a hardware and a software (running on that hardware).

PL 9823 meets MSP430

Sat, 25 May 2024 00:00:00 +0000

Generating signals for PL 9823 using a MSP430

Debugging

mspdebug rf2500 gdb

msp430-gdb -x firmware.gdb

Attention: the gdb in the TI toolchain package is broken, use the one from Debian

Signals Working Cycler

These signals are related to code under tag cycler_works_include_output_stage.

First octets:

Last octets:

Schematics and legend for signals:

Some more explanations

Consider above schematics and the screen shot “Last octets” from the oscilloscope.

Timer TA1 is running in “up mode” to the value 45 set in compare register TA1CCR0. The compare registers TA1CCR1 is set to 10, TA1CCR2 is set to 22. The output mode of the timer is set to “Reset/Set”, which means the GPIO associated with TA1CCR1 (P2.1) and TA1CCR2 (P2.4) are set at the overflow and restart of the counter and reset when the counter matches the associated compare value.

Stratum 1 NTP Server participating in ntppool.org

Thu, 13 Mar 2025 00:00:00 +0000

Just another Stratum 1 Timeserver

Tue, 11 Feb 2025 00:00:00 +0000

This server utilizes ntpsec on Debian on a BeagleBone Black with a UBlox GPS module.

It has been joined the NTP pool, the statistics are available at https://www.ntppool.org/scores/93.241.86.156.

Some additional statistics graphs for the server are available at https://numbers.hottis.de/ntpserver.

Preparation of the BeagleBone

The GPS module is connected via serial line to the UART of the BB.

The additional connection of the PPS output with the PPS device of the Linux running on the BB via a GPIO must be prepared. A device tree overlay must be created and compiled:

Yet Another Debouncing Method

Mon, 30 Apr 2018 00:00:00 +0000

You can find several approaches for debouncing mechanical switches on the Internet, some work better, some not so good.

One common approach is to ignore events in an ISR when they come too fast:<

void count() {
	static uint32_t lastEvent = 0;
	uint32_t currentEvent = micros();
	if (currentEvent &gt; (lastEvent + configBlock.debounce)) {
		lastEvent = currentEvent;
		cnt++;
	}
}

void setup() {
        pinMode(REED_PIN, INPUT_PULLUP);
        attachInterrupt(REED_PIN, count, FALLING);
}

This works very good when only the tipping of a switch is relevant.

Three Phase Inverter - Second Service

Mon, 19 Dec 2016 00:00:00 +0000

I wrote in October about my first try to build a simple three phase inverter, see here. In the first try I used four MSP430 microcontroller, one for the PWM of each phase and one to coordinate the phase shift of the three phases.

In this experiment I put everything on one STM32 microcontroller. Here I used the DMA feature to feed data into the PWM counter and I calculated the sine values at start-up time on the microcontroller. Additionally I put in the driver for a CAN interface, however, it is not yet supported in the firmware.

Three Phase Inverter

Fri, 14 Oct 2016 00:00:00 +0000

Already when I was still in school, about 30 years ago, I was curious to make an inverter using some MOSFETs. I actually was able to build a simple one phase inverter with rectangular signal shape (I used a NE555). Using this thing I drove a transformer to light a blub. However, all of these inverters I built passed by in fire.

Now, I tried it again, not longer using MOSFETs but IGBTs with free-wheeling diode. Moreover, I used some microcontrollers and sine values to feed a PWM to get a sine-alike signal shape. And this time I was able with three phases to drive an asynchronous motor.

Theremin

Mon, 01 Jul 2013 00:00:00 +0000

A Theremin is a rather old electronic music instrument, invented in 1928. It is played by approaching hands to two antennas, without touching them. One antenna is used to manipulate the frequeny of the tone, the other one to manipulate the volume.

This is just another Theremin. Only basic structure of the circuit was taken from many other published Theremin circuits.

Completely new (or at least not found during my Theremin googling) is the digital zero-calibration.

Children Protection for Postfix-based EMail-Server

Thu, 27 Jun 2013 00:00:00 +0000

This small tool implements a whitelist on a Postfix mail-server. It prevents certain recipient addresses (your kids ones) from receiving mail from any not whitelisted address. Any mail from not whitelisted senders is redirected to a delegate (a parent).

The code for this tool can is here: https://gitea.hottis.de/wn/childprot.

Configure the tool by adding this line into the master.cf of the Postfix installation:

childprot unix -   n    n    -    25    spawn user=mail argv=/opt/sbin/ChildProt

and this one to the main.cf:

Mon, 01 Jan 0001 00:00:00 +0000

My Public GPG and SSH Keys

SSH Keys

My SSH Keys

GPG Keys

About

Mon, 01 Jan 0001 00:00:00 +0000

Wolfgang Hottgenroth

Colors in Minicom

Mon, 01 Jan 0001 00:00:00 +0000

To start minicom in color mode use

minicom -c on

Switch terminal emulation to ANSI.

Use escape sequences to actually change the color of text as described for instance here

https://www.lihaoyi.com/post/BuildyourownCommandLinewithANSIescapecodes.html.

The base sequence is \1b[Xm where X is a number as described below.

To get the colors in bright style, use the sequence \x1b[X;1m.

Number	Color
0	reset
1	highlight
7	inverse
30	black
31	red
32	green
33	yellow
34	blue
35	magenta
36	cyan
37	white

Engel des Herrn

Mon, 01 Jan 0001 00:00:00 +0000

Der Engel des Herrn brachte Maria die Botschaft, und sie empfing vom Heiligen Geist. Gegrüßet seist du, Maria …

Maria sprach: Siehe, ich bin die Magd des Herrn; mir geschehe nach deinem Wort. Gegrüßet seist du, Maria …

Und das Wort ist Fleisch geworden und hat unter uns gewohnt. Gegrüßet seist du, Maria …

Bitte für uns, heilige Gottesmutter (heilige Gottesgebärerin), (auf) dass wir würdig werden der Verheißungen Christi.

Lasset uns beten. Allmächtiger Gott, gieße deine Gnade in unsere Herzen ein. Durch die Botschaft des Engels haben wir die Menschwerdung Christi, deines Sohnes, erkannt. Führe uns durch sein Leiden und Kreuz zur Herrlichkeit der Auferstehung. Darum bitten wir durch Christus, unsern Herrn. Amen.

Execute occ in Nextcloud pod

Mon, 01 Jan 0001 00:00:00 +0000

First, look up the name of the pod using

kubectl get pods -n nextcloud

Then, get into the pod using

kubectl exec --stdin --tty NAME_OF_THE_POD -c nextcloud -n nextcloud -- sh

Finally, within the pod

su -s /bin/sh www-data -c "php occ --help"

Gitlab Backup and Restore

Mon, 01 Jan 0001 00:00:00 +0000

Backup

Find the backup directory:

grep backup_path /etc/gitlab/gitlab.rb

Issue backup:

sudo gitlab-backup create

Transfer backup using scp to destination machine.

Backup configuration and secrets:

sudp cp /etc/gitlab/gitlab-secrets.json /backuppath/
sudo cp /etc/gitlab/gitlab.rb /backuppath/

Restore

DO NOT OVERWRITE THE CONFIGURATION ON THE DESTINATION MACHINE. COMPARE IT AND CONSIDER AND EVALUATE EACH DIFFERENCE

Stop processes of GitLab connecting to the database:

gitlab-ctl stop puma
gitlab-ctl stop sidekiq
# check
gitlab-ctl status

Do not stop the whole system since the restore tool has to connect to the database which would also stop in that case.

Gitlab Change BaseURL in Database

Mon, 01 Jan 0001 00:00:00 +0000

Change URL

After a migration changing the base url in the configuration is not enough. It must also be changed in the database.

Adjust the variable external_url in the file /etc/gitlab/gitlab.rb and run gitlab-ctl reconfigure

Adjust the canonical URL in the database:

gitlab-rails console
ApplicationSetting.current.update!(home_page_url: 'https://neue-url.example.com')
ApplicationSetting.current.update!(after_sign_out_path: 'https://neue-url.example.com')

Reading out a value from the ApplicationSetting via the gitlab-rails console is done using
```
ApplicationSetting.current.home_page_url
```
Clear the internal cache:
```
gitlab-rake cache:clear
```

Gitlab Upgrades

Mon, 01 Jan 0001 00:00:00 +0000

Upgrade of a GitLab instance

When upgrading a Gitlab instance, strictly follow the defined upgrade path. Consider to snapshot the filesystem if possible after each step.

Additional, after each step wait until all background migrations are completed before performing the next upgrade step.

To find the versions of a specific package in the Debian apt cache use

    apt-cache madison gitlab-ce

To upgrade to a specific version use

How to add a CA certificate in Debian

Mon, 01 Jan 0001 00:00:00 +0000

Copy CA file with extension crt into /usr/local/share/ca-certificates/.

Call update-ca-certificates as root.

iSCSI on Linux

Mon, 01 Jan 0001 00:00:00 +0000

Preparation

Install open-iscsi, at least on Debian systems.

Use an iSCSI target from Linux

In our setup a Synology NAS at 172.16.200.19 provides the targets.

First, run

   iscsiadm -m discovery -t sendtargets -p 172.16.200.19

to discover all provided targets.

You get something like this

   172.16.200.19:3260,1 iqn.2000-01.com.synology:nas.Target-GitLab.db1c0541e7
   [fe80::211:32ff:febe:da31]:3260,1 iqn.2000-01.com.synology:nas.Target-GitLab.db1c0541e7
   172.16.200.19:3260,1 iqn.2000-01.com.synology:nas.Target-Bitwarden.db1c0541e7
   [fe80::211:32ff:febe:da31]:3260,1 iqn.2000-01.com.synology:nas.Target-Bitwarden.db1c0541e7
   172.16.200.19:3260,1 iqn.2000-01.com.synology:nas.Target-Nextcloud.db1c0541e7
   [fe80::211:32ff:febe:da31]:3260,1 iqn.2000-01.com.synology:nas.Target-Nextcloud.db1c0541e7
   172.16.200.19:3260,1 iqn.2000-01.com.synology:nas.Target-MariaDB.db1c0541e7
   [fe80::211:32ff:febe:da31]:3260,1 iqn.2000-01.com.synology:nas.Target-MariaDB.db1c0541e7
   172.16.200.19:3260,1 iqn.2000-01.com.synology:nas.Target-Backup.db1c0541e7
   [fe80::211:32ff:febe:da31]:3260,1 iqn.2000-01.com.synology:nas.Target-Backup.db1c0541e7

Now, connect to the target using

Magnifikat

Mon, 01 Jan 0001 00:00:00 +0000

Bibellese zum 15.12.2013

1,46 Und Maria sprach: Meine Seele erhebt den Herrn,

47 und mein Geist freut sich Gottes, meines Heilandes;

48 denn er hat die Niedrigkeit seiner Magd angesehen. Siehe, von nun an werden mich selig preisen alle Kindeskinder.

49 Denn er hat große Dinge an mir getan, der da mächtig ist und dessen Name heilig ist.

50 Und seine Barmherzigkeit währt von Geschlecht zu Geschlecht bei denen, die ihn fürchten.

Neovim Setup

Mon, 01 Jan 0001 00:00:00 +0000

Lots of information on nvim can be found for instance here:

Installation of Neovim

On Debian install neovim from the sources, the packages are mostly a bit aged.

git clone https://github.com/neovim/neovim
sudo apt install ninja-build gettext cmake unzip curl
make CMAKE_BUILD_TYPE=Release
sudo make install

On Windows install from binary or using installer, on MacOS use brew.

Debian packages can be found here: https://github.com/neovim/neovim-releases/releases

Configuration

Clone the packer repository:

PuTTY and OPENGPG hardware keys

Mon, 01 Jan 0001 00:00:00 +0000

install gpg4win installed
create or edit the file gpg-agent.conf, usually in c:\Users\XXX\AppData\Roaming\gnupg\:
```
enable-putty-support
enable-ssh-support
use-standard-socket
```

Quotes

Mon, 01 Jan 0001 00:00:00 +0000

Und dann in deinem Arm, alles gut, alles andere egal

2025-01-22 Alles Du, Dota Kehr

Es ist immer was los, aber es passiert nichts.

2025-01-14 Steinhammer, Thadeusz

Sie steht gut da. Aber die Seele setzt sich nicht dazu.

2025-01-14 Samuel Overbeck in Steinhammer, Thadeusz, S. 68, 71

Resize HDD on running system

Mon, 01 Jan 0001 00:00:00 +0000

Resize target on VMWare or on Synology or where ever it is provided
Stop services using the disk
Unmount the disk
Run e2fsck -f on the disk
Rescan disks using echo 1>/sys/class/block/sdx/device/rescan (replace sdx by actual disk device)
Extend partition using resize in cfdisk
Extend filesystem using resize2fs on extended partition
Mount the partition
Start services

snmpwalk with numeric and text output of oid

Mon, 01 Jan 0001 00:00:00 +0000

snmpwalk -v 2c -c $COMMUNITY -On $HOST $BASE_OID | while read -r line; do 
  oid=`echo $line | awk '{print $1}'`
  textoid=`snmptranslate $oid`
  value=`echo $line | cut -d ' ' -f 3-`
  echo "$oid ($textoid): $value" 
done

Solution for Prince of Persia 1

Mon, 01 Jan 0001 00:00:00 +0000

Lösung Prince of Persia 1

Komplettlösung zu “Prince of Persia 1”

Zuallererst mal zur Joysticksteuerung: Wenn Ihr beim
Springen den Feuerknopf gedrückt haltet, macht der Prince
einen ‘Klammersprung’, d.h., bei grossen Entfernungen
springt er an die gegenüberliegende Wand und klammert sich
dort fest. Mit dem Joystick dann einfach nach oben drücken
und schon ist’s geschafft.

Ausserdem kann man teilweise Decken aufstossen (VORSICHT,
wenn die Platten dann runterfallen!); aber dies ist für das
Spiel nur dann nötig, wenn man in einer Sackgasse steckt
und der Weg über die Decke weitergeht. Ansonsten sind dort
meist ’nur’ Potions versteckt. ACHTUNG: Um das Spiel
zeitlich zu schaffen empfiehlt es sich, (wenn nicht
wirklich nötig) die Deckengänge NICHT zu benutzen. Das
Spiel an sich verfügt über 13 Level (12 Level + den
Abschlußlevel mit Kampf gegen Jaffar). Wenn man alle Level
kennt und perfekt spielt (nie kaputt geht) braucht man
trotzdem ca. 45-50 min. Um das Spiel also zu schaffen, muß
man in allen Leveln den Weg kennen. Da dies natürlich nicht
beim erstenmal klappt ist klar; also immer ein bis zwei
Level weiterarbeiten und gut auskundschaften.