Heltec WifiKit 8

Written by marcelpetrick on June 11, 2019

Ordered myself two Wifikit8 Esp8266-based boards from Aliexpress.
Received them after roundabout two weeks and now the fun can start.

With the integrated 0.91″ display (128×32 Pixel) a lot of effort for integrating some display or LEDs can be saved. Just noticed that a LiPo-charger is built-in as well, wow. For 4,50 € not a bad choice. But I am not 100% sure if this is the real device or some copycat – nevertheless: in the end the functionality matters.

First project-idea is to create an extended and verifyable version of the random-reviewer. With display of the currently chosen person, a big buzzer-button as trigger and a web-interface for those who doubt the true randomness ..

good guides:

https://robotzero.one/heltec-wifi-kit-8/ – hints for the board itself
https://www.bastelgarage.ch/heltec-wifi-kit8-board-esp8266-32mbit – hints for the board itself
https://github.com/olikraus/u8g2/wiki/u8x8reference#drawstring – library for drawing text; works well

Qt: clean includes

Written by marcelpetrick on May 20, 2019

(I’ve decided to follow a more agile workflow: instead of creation a “one post covers the whole topic”-post, to post also updates for each step. Article will be therefore edited while “doing”)

Last week I’ve cleaned Qt-includes for a larger project. Like #include to #include how it should be. With proper indirection, so that the Qt-library handles how and where the class is implemented.
A colleauge raised the question, why not use #include to be even more precise and to see the used module directly (needed for the CMakeLists or qmake).

First step: identify all used Qt-includes

$ git grep "include <Q" | cut -d : -f 2 | sort -u
# include <QApplication>
# include <QAtomicInt>
# include <QDebug>
# include <QFileDialog>
# include <QHBoxLayout>

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$ git grep "include <Q" | cut -d : -f 2 | sort -u

# include <QApplication>

# include <QAtomicInt>

# include <QDebug>

# include <QFileDialog>

# include <QHBoxLayout>

Greps all includes starting with an uppercase Q; then split the result at the “:”; then sort und make it unique

Second step: create a replacement-list and a (python?) script which does this for all .h/.cpp-files
tdb

C++: proper init for double/float and the proper check

Written by marcelpetrick on May 9, 2019

Problem was that I initialized some doubles with 0.0 and then hoped that the imported values are assigned, which does not happen always. So a check was needed. But checking if(0.0 == x) is a really bad idea. MinGW will tell you too (as other compilers).
So I was searching for a proper way to check against 0.0. And then I found a better idea: initialize with NaN and use the standard-check against this. Much better!

#include <limits>
..
    // init them with NaN to prevent later issues
    double x{std::numeric_limits<double>::quiet_NaN()};
..
    if(isnan(x))
    {
        qDebug() << "uninitialized"; // todom remove
        return false;
    }

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#include <limits>

..

// init them with NaN to prevent later issues

double x{std::numeric_limits<double>::quiet_NaN()};

..

if(isnan(x))

{

qDebug() << "uninitialized"; // todom remove

return false;

}

(addendum: I know, a variant would be the best to fix the given task.)

Advanced debugging: find call which triggers Qt-errors

Written by marcelpetrick on April 26, 2019

Currently the debugging version of the Qt-libraries is not available. But I receive a report "QIODevice::write (QIODevice): Called with maxSize < 0" deep within them.
Our codebase is quite large, I am more familiar with other sections and let's say it: some is 'legacy'. So, where to start looking?!?
Yesterday I remembered a trick to get via call-stack to the last-recent position where our functions trigger that mistake.

Inserted in the main.cpp after show from the MainWindow was called a

qInstallMessageHandler(messageHandler);

1	qInstallMessageHandler(messageHandler);

which stands for this

void messageHandler(QtMsgType type, const QMessageLogContext &context, const QString &msg )
{
    Q_UNUSED(context);
    switch( type )
    {
    case QtDebugMsg: qDebug() << msg.toLatin1().data(); break;
    case QtWarningMsg: qDebug() << msg.toLatin1().data(); break;
    case QtInfoMsg: qDebug() << msg.toLatin1().data(); break;
    case QtCriticalMsg: qDebug() << msg.toLatin1().data(); break;
    case QtFatalMsg: qDebug() << msg.toLatin1().data(); break;
    default: qDebug() << msg.toLatin1().data(); break;
    }
}

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void messageHandler(QtMsgType type, const QMessageLogContext &context, const QString &msg )

{

Q_UNUSED(context);

switch( type )

{

case QtDebugMsg: qDebug() << msg.toLatin1().data(); break;

case QtWarningMsg: qDebug() << msg.toLatin1().data(); break;

case QtInfoMsg: qDebug() << msg.toLatin1().data(); break;

case QtCriticalMsg: qDebug() << msg.toLatin1().data(); break;

case QtFatalMsg: qDebug() << msg.toLatin1().data(); break;

default: qDebug() << msg.toLatin1().data(); break;

}

Add a breakpoint in the messageHandler and debug the app. Maybe disable the breakpoint until you start to trigger the critical functionality.
When it breaks, you have a nice callstack and can backtrace where it came from :)

ESP32: integrated the YL-69 for moisture-metering, also fried my first BME280

Written by marcelpetrick on March 12, 2019

Acquired a Bosch BME280 for improved humidity, air pressure and temperature-measurement (DHT22 can’t read barometric pressure) and tried to attach it via I2C.
Let’s keep it short: the sensor got very hot after several tries to find the correct wiring. Even using the i2c-scanner testprogram did not yield any results. But I learned how to use the breadboard more effectively. The burnt IC will be sold as ‘Lehrgeld’ 😉 (Oh, the days when I fried my AMD Duron, because I thought that a CPU won’t heat up so fast at boot. Boy was I wrong.)
Integrated then at least via analog reading the YL-69 moisture sensor. Worked well and on first try. Guess I just need to read much, much .. more about I2C, wiring and the sensors.
Another lesson learned: if you want to see really badly structured, basic coding: check tutorials for microcontrollers :/ (especially mine ;))
———
Code is committed and pushed to github.
Output is something like:

Humidity (DHT22): 72.90 %	Temperature (DHT22): 24.10 °C 
Temperature (internal): 31.11 °C
Moisture (YL-69): 27%

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Humidity (DHT22): 72.90 % Temperature (DHT22): 24.10 °C

Temperature (internal): 31.11 °C

Moisture (YL-69): 27%

breadboard-setting featuring a Haworthia and WerNO!:

ESP32 and DHT22: temperature and humdity

Written by marcelpetrick on March 5, 2019

To give my (non-existant) skills for microcontrollers and reading out sensor-values a kick-start, I decided to connect today an DHT11 to the ESP32.
So, at first I realized I have no clue how a breadboard works, then that I need a calculator to determine the resistors properly, then “how to determine the correct pin-numbering”, then … it did not work, no matter what I tried. The C++-code was the least issue. Several sources provide examples, also with webserver (looks like everyone ~stole~ got inspired from each other ..), but the read-out always failed.
Luckily I had two (a bit more ‘expensive) DHT22 at hand and it worked like a charm!

Lessons learned: 0. accept that you know nothing 1. reading and experimenting is fun 2. seeing finally a presentable result is great <3

Result:
* code
* output:

Humidity: 71.20 %	Temperature: 24.40 °C 
Temperature (internal): 31.67 C

1 2	Humidity: 71.20 % Temperature: 24.40 °C Temperature (internal): 31.67 C

advanced whitespace-correction

Written by marcelpetrick on February 26, 2019

(for CMake/C++-projects)

Find all fitting files and run the fixer-script in parallel over it.

 ( find . -name "CMakeLists.txt" ;   find . -name "*.cmake" ;   find . -name "*.h" ;   find . -name "*.cpp" ) | parallel --bar ../removeTrailing.sh

1	( find . -name "CMakeLists.txt" ; find . -name ".cmake" ; find . -name ".h" ; find . -name "*.cpp" ) \| parallel --bar ../removeTrailing.sh

After playing for a while with sed and awk and not being able to get a fitting solution, I decided to create my own as python-script. It squashes all consecutive double-whitespace-lines (and adds one to the end if missing).

Or “run it on the files changed for the last commit”:

$  git diff --name-only HEAD~1 HEAD | parallel --bar ../removeTrailing.sh

1	$ git diff --name-only HEAD~1 HEAD \| parallel --bar ../removeTrailing.sh

Sources:
removeTrainling.sh
squashMultipleWhitespace.py

How to get GNU parallel (developed by Ole Tange):

(wget -O - pi.dk/3 || curl pi.dk/3/ || fetch -o - http://pi.dk/3) | bash

1	(wget -O - pi.dk/3 \|\| curl pi.dk/3/ \|\| fetch -o - http://pi.dk/3) \| bash

Updating to the current package of Qt Charts (from the commercial version)

Written by marcelpetrick on February 1, 2019

Qt (or Digia? or how was the company-owning-Qt called at that time?) released in 2014 the version 1.4 of their Charts add-on for Qt. It was available only for the commercial-license and had some distinc namespace-requirements. And was also quite bare-metal.
Further development lead to more opportunities regarding the emitted signals for the cursor-handling (pressed/released instead of just clicked, for instance) and it became part of the regular package for Qt.

## Advice for a CMake-based project ##

If you want to maintain and upgrade your legacy code, then:

add “Charts” to your find_package:

find_package(Qt5 COMPONENTS Widgets Charts REQUIRED)

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find_package(Qt5 COMPONENTS Widgets Charts REQUIRED)
change the namespace inside the CMakeLists from “former naming” to “Qt5::Charts”
remove the dependency to the old package in the top-level CMakeLists.txt
replace inside the h/cpp all occurences of “QtCommercialChart::” with “QtCharts::”
replace inside the h/cpp all occurences of “QTCOMMERCIALCHART_USE_NAMESPACE” with “using namespace QtCharts;”
update the installer-creator-script(s) to include the Qt5Charts.dll

Et voilà , it should build now.

Retrospective view at 2018

Written by marcelpetrick on February 1, 2019

The first month of 2019 already passed. And we passed it with flying colors!
But let’s have a look at 2018 – a year full of challenges and success: I’ve worked full-time, organized and participated in advanced courses for Python and in Requirements Engineering (officially: IREB Requirements Engineering Foundation Level-approved) and pursued a new employment as software engineer.

And I wrote some software in my spare-time, as you can see in the graph for the public github-repositories. The gaps in the commits can be explained with the birth of my daughter and the time where I acquired the new job and moved nearly 900 km across the country. Yay! Nice personal projects were and are Cullendula and the Daily Coding Challenges, which I solve mostly with fully Unit-tested Python (3).

More new, hands-on knowledge was gained in the area of CMake and Qt-charts.
Well – 2018 was great. Let me make 2019 greater! 💪

Fixing ~crappy~ no-good Qt-includes

Written by marcelpetrick on January 29, 2019

How to locate all includes of that style:

#include <QtWidgets/qcombobox.h>

1	#include <QtWidgets/qcombobox.h>

with proper

#include <QtWidgets/QComboBox>

1	#include <QtWidgets/QComboBox>

Fired up https://regex101.com/ and set it to PHP and created an expression, which matches:
starting with slash, then a q, then characters, then . then h

\/[qQ][a-zA-Z]+\.h

1	\/[qQ][a-zA-Z]+\.h

(Replace & check has to be done by YOU ;))