,Performance tests in several basic scenarios to estimate languages runtime performance

​Lately I was trying to understand how virtual memory works and how JVM work and perform.
My intuition was ' if a JVM is written in C, it is probably less performant than C '
So after a lot of reading and investigations I found out that the story is much more complicated then I have initially thought.
JVM has many optimization which makes it very fast most of the time, it does has an overhead but the optimization in JIT make every thing worth it.
basically the JVM will loaded into native virtual memory (and be shared with other processes when possible)
it will use sophisticated algorithms to allocate memory on the native heap to create managed heap.
it will JIT to perform well, will vectorise  actions and what not to make the run time overhead worth it.
At that point I was thinking ' OK, so javascript is a VM, it should probably also perform well '
But benchmark tests online showed different things. I know javascript is single threaded but this tests take this into account (For example fork many process).
The V8 engine is highly optimized and make all kind of clever things to perform faster, for example making a behind the scene classes and types and caches to speed up the execution.
V8 is still young compared to C and Java so I am sure it will be even better. my impression is that optimizing a dynamic language such as javascript is harder than a language like java, but I might be wrong here.

Any way I thought that I have to make my own test to better understand the performance difference in various situations, so here it is, my results

​hope you will find this info helpful!

Comments are more the welcome.

​What to host you android custom library on your own  public github account
(Remote binary dependency)
Let's start:

• Start with this one
• Continue with this
• And here
• And this

when I was building my custom light 4 touch switch panel for my smartHomeDIY I discovered Arduino uno and nano has only 2 hardware interrupts, 
luckly,after searching for a while, I found a blog that helped me to overcome this limitation.
The solution is: pin change interrupts which are supported by the Arduino uno and nano: .

Regular hardware interrupts can be registered for raising or falling or change interrupt, but the pin change interrupts, as their name suggests, are only capable to deliver interrupts when the pin senses a voltage change in any direction, if you need to know which pin was changed you will have to read all pin states (or relevant pins) to know the new state and compare it to the old state (which you have to save on you program.
a small workaround in my case was to register for 2 hardware interrupts and for the other 2 required interrupts I used the pin chagne mechanism, but there are good news, the pin change interrupts are grouped into group of pins 

• A0 to A5
• D0 to D7
• D8 to D13

So I just used different group for each switch and used a counter to ignore the second interrupt - leaving me with a raising interrupt.

When writing code and delivering to customers you usually will find your self (or someone else ...) debugging your code throw log files and probably a lot of them.
I know I do :)
​

So I wrote my self a small helper tool based on Electron and vue.js + vuetifyjs. which makes it cross-platform.
And I made is open source just for you :)

​Logx

You can just drag and drop you files on it and start 'finding' , setting colors for specific phrases or filtering in or out any phrase you like.
​Enjoy.

BTW I used this cool template code from github, to get started easily...

Just note that this is a work-in-progress, feel free to file in issue you find on github :)

If you like your realtime logs monitoring on terminal from anywhere while using your favourite searching and colouring tools like me, then you must read this.
Azure DC/OS is a great tool, but getting the logs from each microservice instance using the dashboard is slow and complected.
So for the rescue here comes dc/os CLI.
This command line utility will make you life much easier in just a couple of steps

1. First ssh into your master dc/os node [help!]
2. Install dc/os CLI like this.
3. Then just type 'dcos task log <your-micro-service-name-here>  --follow'
   1. This will aggregate logs from all instances of this service.
4. To see logs of the master just type 'dcos node log --leader --follow'
5. To lean some more cool commands - read here. here and here

Good luck  and happy debugging ... :)

During my search to start and learn embedded system programming, I was not able to find a good reference to start with.
I was searching a reference that will easy me in into this topic.
Because this topic not only hard to learn it is also consists from several topics:

• Hardware architecture
• CPU architecture in my case ARM-Cortex
• Hardware protocols and communications such as I2C or SPI
• In Some cases analog electronics and digital basic electronics
• And finally professional  c and c++ coding in relation to embedded hardware programming.

So after searching a lot and for a long time I came up with the following YouTube playlists and couple of links that will ease you into this very interesting field.

1. Intro
2. I2C,I2C
3. SPI, SPI
4. UART

• Microcontroller (Arduino) TimersMicrocontroller (Arduino) Timers
• Port Manipulation, Bit Math, Faster PWM/ADC
• Analog-to-Digital Converter
• PWM, And another one
• Best 555 tutorial ever, 555 Timer
• OpAmp (Operational Amplifier), Another one, And Another one, and this

• ​​Basic Electricity - What is an amp?
• Basic Electricity - What is voltage?
• Basic Electricity - Power and watts
• Basic Electricity - Resistance and Ohm's law
• All about batteries
• Capacitors
• Transistors
• MOSFETS and BJTs
  
• How does a Diode work
• What is a schottky diode?
• What is a zener diode?, And more
• Inductor basics - What is an inductor?, And here, And here
• Passive RC low pass filter
• Passive RC high pass filter
• Voltage divider​​
• Comparator
• How do antennas work​​
• 
  

• ​Oscilloscope tutorials

Today I wanted to talk about a video that inspired me by Joop Brokking
it’s a tutorial video about STM32F103C8T6 ARM STM32 Minimum System Development board known also as the Blue Pill and how to program it to use the MPU-6050 sensors board via I2C

In this video Joop tested the i2c communication from the MPU-6050 sensors board to the STM32F103C8T6 ARM-M3 Micro controller

He used a real hardware Oscilloscope to test the signal
and show the errors and how to fix them

These hardware Oscilloscopes are very useful
but could also be quite expensive, especially for a beginner

So I thought why not replicate the hardware setup and try the same experiment with my Hantek 6022BE PC USB Digital portable Oscilloscope
And see how the single looks like or if it’s even capable measuring these kind of signals

​The Hantek 6022BE PC USB Digital portable Oscilloscope, is a PC USB Digital portable Oscilloscope that features 2 20MHz analog Channels at 48M, and single can be shown on the computer with a dedicated software that comes with it
​
I have tested the 100KHz and 400KHz with no problem
You can see the clock signal and the data signal
As can be seen here it works great and it only costs around 70$

There are multiple ways to investigate the signal
and the software has some nice measuring capabilities

But of course it has less features than the hardware ones
and probably will not work at the higher scales of Mhz signals

I have also tried the same experiment with my USB 24MHz 8 Channel Logic Analyzer and the results were also great and this one only costs around 10$, but cannot debug analog signals only digital ones (i2c, spi, UART , etc...)

To program the STM32 you will beed an FTDI programer connected to the STM32 B6 and B7

Check out the full tutorial about programming the STM32F103C8T6 here