A section with links to more information on the web about the XIAO was added to the original post [...more]
With a USB-C port and with two I/O pins providing USART Tx and Rx connectivity, the XAIO can fill in a USB to serial converter in a pinch [...more]
The post contains a general approach to creating and using
GFXfont type fonts containing up to 224 characters arbitrarily chosen from plane 0 of the Unicode character set. This proposal respects the
Adafruit-GFX library's prime directive which is to maintain compatibility with existing Arduino sketches, since no changes are made to
Adafruite-GFX. The post is similar to the one published on October 23 and replaces the October 8 post which was withdrawn
[...more (in French)]
The default licence for my code on this site has been changed to the BSD Zero Clause License created by Rob Landley. I have also finally got around to being more explicit about the copyright for the posts found here [...more]
A few days ago, someone sent a message to my Facebook account. Unfortunately, I somehow managed to delete the message without reading it nor can I remember the coordinates of the sender. I am sorry that I cannot reply and hope that the sender will accept my apologies.
Please do not try to reach me through Facebook/Messanger which is reserved for family and friends. Instead use the e-mail link at the bottom of each page and you will get a reply.
This is a much needed update of the original October 2017 post on how
to set up rsyslog on Raspberry Pi OS as a centralized
syslog server and how to
enable remote error loggin in Tasmota
By default, proportional fonts that can be used with the Adafruit GFX Library and other libraries that are compatible with GFX fonts are limited to the 95 printable 7-bit ASCII characters (code points 32 (0x20) to 126 (0x7E). This is my attempt at supporting 8 bit character sets which is throwback to the pre UCS, pre Unicode code page concept. A modified
fontconvert utility, called
fontconvert8 can extract any subset of glyphs from a TTF font although I have included only two examples: ISO 8859-1 (Latin 1) and ISO 8859-15 (Latin 9). Then I have written two
utf8tocp functions to simplify displaying UTF-8 encoded strings using these fonts with displays. This is not a universal solution, anyone wanting to use a different code page than the two provided will have to modify
fontconvert8 source and the
French Diacritical Letters with Adafruit GFX Fonts
Removed, soon to be replaced with something better... hopefully. Once again I have run into problems associated with French diacritical letters. The fonts supplied in the library that I use with a TFT display only contain ASCII characters from 32 to 126. However, the library is compatible with Adafruit_GFX type proportional fonts and it is relatively easy to add additional glyphes taken from the Latin-1 block in Unicode that corresponds to the ISO 8859-1 code page
Installation and configuration of Ubuntu 20.04 Server on an older computer with a lesson learned about network configuration in Ubuntu [...more]
Self inflicted wound: I had not expected that changing the domain name servers would break time synchronization on the backup server [...more]
Belated Spring Cleaning
After delaying for quite some time, I have begun the long and boring job of cleaning up this site. This involves a slightly fresher and more compact start to each page as seen here. The home automation and programming indexes were removed mostly to make my life easier but also because I was feeling increasingly cramped with that choice.
There are now only two search engines on tap for a local search. I chose DuckDuckGo and StartPage because of their privacy claims. This choice is not an endorsement, as I have no way of verifying if a site tracks searches and uses, shares or sells the data. Searches limited to this web site with the usual search engines can be done from the archives page.
Converting the whole site will take quite some time. So far, the posts published in the last 12 months and a few older ones have the new look. Hopefully, nothing is broken but please send me an e-mail (link at the bottom) if there is something wrong.
The WireGuard package is now included in the Debian and Raspbian
testing repositories. The latter is very good news, because the
While Raspberry Pi OS, the newest version of the "official" operating system for the Raspberry Pi, has changed name, it remains based on the 4.19 Linux kernel just as Raspbian Buster had been. Nevertheless, I tried to improve my post on the installation and configuration of a WireGuard virtual network server, because it is one of the most consulted pages on this site. There is an addendum showing how to install WireGuard on all Raspberry Pi models using a "beta" Raspbian WireGuard package [...more]
PlatformIO now supports the Seeeduino XIAO. Some prefer PlatformIO to the Arduino IDE. New users of PlatformIO or those that are curious about that programming environment may want to consult this short post on how to upload a very simple program to the XIAO in that environment [...more]
While Raspberry Pi OS and Raspbian Buster are both based on Debian 10 and the 4.19 Linux kernel, there are differences that made my Febrary post about a ubiquitous DS3231 real-time clock with an AT24C32 EEPROM module out of date . I found it easier to leave the old post in place, and copy and paste most of it in this new article, only changing what needed to be fixed in the new OS. That way, it will not be necessary to refer to the old article unless one is still using Raspbian [...more]
Once again, I will try to set up reasonable backup strategies. In this post, I discuss an important part of that endeavour, backing up the home automation server data files [...more]
This post is another of those that document my never ending need to learn something about micro-controllers. This time I am investigating the Serial Peripheral Interface (SPI) on the Raspberry Pi. I examine both the hardware and the Python
spidev module and even attempt to update a "well-known" document about the later which was available about five years ago
There are some good explanations on how to add a serial communication interface on SAM D21 based boards. However all those that I have found are for boards with many more I/O pins than the XIAO so that they are not that pertinent for this tiny board. In this post, I explain just what the problem is and how it is nevertheless possible to add a supplementary SPI, I²C or USART port on the XIAO as long as another type of communication interface is forgone [...more]
A very knowledgeable reader of the first version of the Overview of the SAMD21 Arm Cortex-M0+ Based Seeeduino XIAO kindly provided instructions to manually install the XIAO board definition in the PlatformIO development environment. Because all the hard work was already done for me, it was a simple two-step procedure [...more]
Using the XIAO in master mode to control and I²C slave device was already discussed in the first look at the Seeeduino XIAO. The topic of I²C communication with the XIAO is again the topic but this time the emphasis is on data exchange with a Raspberry Pi. To the latter, the XIAO will appear to be an I²C analogue light sensor [...more]
For a few reasons, I decided to rewrite in large part the instructions on how to self-host a WireGuard
virtual private network on a Raspberry Pi. For one thing, the original post was rushed because at it was difficult to
get the correct repository keys. At the time, I was in the process of writing a long winded yet superficial explanation of VPN. Reading my old post
when answering a query from someone, it became clear that there was a supposition that readers had read that non-existent dissertation.
Clearly, pieces of the puzzle were missing. Another problem was that the old post was getting... old. More bits were expended on
Stretch than on
Buster which is now on its third edition
While reviewing my ESP8266 router watchdog code, it struck me that using a blocking (or synchronous) ping library to check the status of the Internet connection was not the proper approach. In this post, I present an example project that monitors if the Internet can be reached using the AsyncPing library by akaJes [...more]
This post contains my first impressions of the Seeeduino XIAO from Seeed Studio. Because I don't really have much experience with micro-controllers except for a bit of work with the ESP8266 and the occasional experiment with Arduino boards, this overview will be at a rather superficial level. Nevertheless, it describes some 15 Arduino sketches showing different capabilities of this new development board. Hopefully, this will be of interest to others starting out with this impressive little board [...more]
Seeed Studio has come out with a new board called the Wio Lite RISC-V with ESP8266. The unusually shaped board is based on the 32-bit RISC-V GD32VF103CBT6 micro-controller by GigaDevice. In addition there is a Wio core based on an ESP8266 which should provide Wi-Fi connectivity. The development software is not yet completed at least for the Arduino platform, but I did manage blink the on board LED with the PlatformIO development environment on a Linux desktop [...more]
These are my first steps with the Sipeed Longan Nano based on the 32-bit RISC-V GD32VF103CBT6 micro-controller by GigaDevice. Development of three Blink projects is done in the PlaformIO environment using the Arduino framework on a Linux desktop. The first blinks an LED, the second also sends the state of the LED to a serial port while in the third, the state of the LED is shown on the included display [...more]
This is about using a Raspberry Pi as a hardware watchdog of another Raspberry Pi. The watchdog Pi could be a Raspberry Pi Zero or Zero W while the monitored Pi is a "mission critical" server such as a home automation system. Hopefully, the intelligent watchdog will prove better than the hardware watchdog for crypto-currency mining rigs that I have been using for some time, but which suffers from three problems which are important enough to warrant its replacement [...more]
In preparation for the new hardware watchdog that will monitor the home autpmation system on a Raspberry Pi, I delved into the details of software and hardware resets of the Pi under the Raspbian operating system. I found that both aspects were well thought out by their respective developers so that it will be relatively easy to create an "intelligent" hardware watchdog for the Pi [...more]
Although the hardware watchdog for crypto-currency mining rigs has been operating without apparent problems as a device for monitoring the home automation system for several months, I am not entirely satisfied with it for three reasons. It is time to develop a replacement. So here is the announcement of a research program on this subject. Please excuse this pompous last sentence, but I intend to document five or even six approaches in the coming weeks. [...more]
This post discusses available I2C buses on the Orange Pi PC 2. It shows how device tree overlays are used to enable up to three I2C physical buses, two available on the 40 pin GPIO connector and the third on the cameral serial interface connector. It also illustrates how compile and enable a custom overlay that installs a driver for DS1307 compatible real-time clock using one of the physical I2C buses. [...more]
Yet another Bluetooth related post, but this time the context is different. The post describes setting up Bluetooth on an Orange Pi PC 2 (an Allwinner H5 based single board computer) running the latest version of Armbian Bionic [...more]
Somehow, I got sidetracked while trying to follow up the previous post with DS3231 real time clock alarms and the SQW interrupts. Instead I looked into how the DS3231 and Linux keep track of centuries and the day of week [...more]
When installing a new hardware clock, I learned a bit more about the DS3231. The clock module also contains AT24C32 type 32K bit EEPROM memory (4K 8-bit bytes). Rereading the post, I realize that its main subject may very well be the I2C bus on the Raspberry Pi [...more]
Six months ago I purchased an Orange Pi PC 2 which is a single board computer based on the Allwinner H5 system on a chip. I never finished writing up about my first impressions. Now that the board is no longer available, I have reexamined the board. Hopefully the post will be of some use to new owners of other boards based on the H5 that want to use Armbian Bionic as the operating system [...more]
After fumbling around for a couple of hours, I have finally managed to flash the traditional blink sketch on an ATtiny85 with the Sparkfun Tiny AVR Programmer using the Arduino IDE (version 1.8.10) in Ubuntu 18.04. Perhaps others will run into some of the difficulties I encountered so here is how I go about it [...more]
Temperature and Humidity Sensor and Reboot/Shutdown Switch for the Raspberry Pi
Two additional sections have been added to the never ending post on Various Hardware with Raspbian Buster Lite. The first shows just how easy it is to connect a DHT11 or DHT22/AM2302 temperature and humidity sensor to a single general input/output pin of the Raspberry Pi. The second shows how to add a reboot/shutdown switch to the Pi.
Here's how to upgrade the U-Boot boot loader of a headless La Frite (no monitor and no keyboard connected) from a Linux computer and upload an operating system to the eMMC memory module of the single-board computer. Libre Computer [...more]
The solution that I was using for the problem causing Domoticz to shut down if there was time synchronization
problem does not work in Ubuntu 18.04 (Bionic).
The problem is discussed at length and a new solution using a
systemd unit file to start the service is provided. I
removed the lengthy discussion in the guide to Home Automation Servers on Raspbian
Buster Lite and only show how to use a unit file to start Domoticz
This is about using a cheap so called USB watchdog meant for cryptocurrency mining rigs as an external hardware watchdog for the Raspberry Pi. This is a single relay watchdog which performs hard resets as a last resort. Perhaps later I will test the ubiquitous two relay USB watchdogs that appear to be much more flexible [...more]
Real-Time Clock on Raspbian
The section on the RTC in Various Hardware with Raspbian Buster Lite has been rewritten. I am quite happy to report that installation of a real-time clock is now much simpler in Buster. However, I still have questions on the subject and I have been investigating time keeping in Linux on and off over the last few days. Will I ever emerge from that rabbit hole? And if I do, will there be anything worthwhile to say about it? Stay tuned...
Report on Progress or Lack of...
I am making slow progress with the guide to installing a home
automation system using Domoticz on
a Raspberry Pi running Rasbian Buster Lite. The
third part on installing
hardware, still in draft form, is taking longer than expected as
I stumble with changes because of the new version of Rasbian.
I am striving to ensure that each step described is warranted. For
example, I have found out that it is not necessary to explictely update
the real-time clock nor is
ntp needed. I am also learning
perhaps more than I wanted to know about
posts need to be updated. The fight against one of the banes of the Internet,
the out of date how to blog, continues.
Want to git rid of all those socket errors and MQTT disconnects occurring for not apparent reason? Just upgrade your ESP8266 device firmware [...more]
This is a major update to the initial October 27 post. There is a
better explanation of how to do a first boot of the Raspberry Pi which
now includes instructions to connect to the Pi with a USB to serial
Information for neophytes sidebar are
collapsible which hopefully makes the layout cleaner. The presentation
has been slightly reorganized to make it easier to follow the different
paths to the initial installation of the operating system. Two sections
that are more hardware related have been moved to the third post of the
series on the subject. An incomplete draft of the third post is up so that
these two sections remain available.
This is part 2 of the series of posts about installing a home automation system around Domoticz on a Raspberry Pi with Raspbian Buster Lite. It covers installing the major services that are needed for the home automation system: the home automation server itself, an MQTT broker, a Web server, and others services that I find quite useful [...more]
This is just a list of tips and tricks that can be found in the Domoticz documentation, Wiki or Forum that I find useful and decided to compile for easy retrieval. [...more]
This is a first part of a three part series of posts that will chronicle the installation of a home automation system based on Domoticz. This first part describes in excruciating detail steps that can be followed to install the latest version of Raspbian Buster Lite on a Raspberry Pi. I hope it will be useful for a newcomer to the ubiquitous single board computer. [...more]
In the hope of making my home automation system more reliable, I ordered hardware watchdogs from Chinese vendors on eBay and Aliexpres. One vendor sent the wrong item. The other sent what I ordered but there is no information about it. I think I have the basics of how the watchdog works, but can someone provide me with more detailed information? [...more]
When a microcontroler project needs more input and output pins than the available number, it is always interesting to use a single pin for more than one purpose. I show in this post how to use a single GPIO pin as an output to control a light-emitting diode and as an input to read the state of a normally open push button switch. [...more]