A very quick introduction to QEMU

If you’re developing your own applications for Raspberry Pi:

There’s a never-ending question on testing your results.

Copying:

  • New version of your app into Linux on your RPi and running it or
  • New disk image to microSD and booting entire device

Doesn’t seems to be a huge problem.

But, when you have to do this dozens of times each day than an emulator-like questions appears.

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Border-less full-screen console app in Ultibo

I made my first project in Ultibo and compiled some example one. Everything was just fine (actually — perfect), if not for that green border with Ultibo name and release version.

Don’t get me wrong. I already love UItibo and will spread the word. But, for security reasons, I’d like to get rid of any info that clearly communicates what was used to build particular piece of software.

Fortunately, with a small research (here and here), it turned out that the solution is very easy.

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3.5 inch GPIO display and RPi

There are a lot of displays for Raspberry Pi. We can list them by image technology:

And by connection method:

There are a lot of arguments and parameters to consider when picking one that is best for you:

  • DSI is the most expensive, but leaves both HDMI and GPIO port free
  • HDMI is cheaper, but occupies one USB port (powering) and of course HDMI port
  • GPIO is the cheapest solution, but occupies GPIO port which is not acceptable in most scenarios

I have decided to buy the last one because it was purely for testing purposes.

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Get started with Raspberry Pi

In this quite old article I have provided just a typical non-sense introductory blah, blah about playing with Raspberry Pi. People who hasn’t done anything yet to their RPi box where sent there to the original “Get started with Raspberry Pi” article at the RPi’s homepage.

Now, it is time to write my very own “getting started” article. A short list-command memo of what should be considered after you unpack, power up and access via SSH your next RPi box.

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Login as root user to Raspberry Pi

As in this article, you cannot login as a root user in Raspberry Pi (neither locally nor via SSH), because you don’t know the default’s root password. In this article, I’ll show you how to change it to be able to login to it, but only locally (still no SSH access), which is good.

Again, as in here, you should never, ever access or use root account. Instead you should use pi user (after changing its default password) and elevate it to superuser with sudo su or by casting sudo in front of each console command.

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All Raspberry Pi default logins and passwords

I don’t like unnecessary blah, blah and I don’t like blogs bloated with ads, so I decided to steal this source and transform it into a simple list of default logins and passwords on various Raspberry Pi bases and clones.

All the glory (copyright and authorship) goes to tutorials-raspberrypi.com.

You read more about users at base Raspberry Pi (no clone) here.

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Developing applications for Raspberry Pi or Linux

Depending on: project’s scope, business expectations, your knowledge and Raspberry Pi’s role you can develop software for RPi in mainly three ways:

  1. Turn Raspberry Pi into API-like webserver with node.js and do all the programming in clients.
  2. Develop a HTML/CSS/JS application
  3. Develop an native Raspberry Pi app

All of the above require you to:

  • Develop a regular Linux app
  • Optimised to use hardware and computing power of Raspberry Pi
  • Run it in Raspbian OS or any other Linux distribution of your choice

And, if you really want to get your hands dirty and truly have no limits then you must forget about Linux and start thinking about Ultibo (there’s a separate article for that).

Developing in Ultibo (or similar complete embedded development environment) requires a lot of expertise, development knowledge and practice. And simply isn’t an option for all. Especially, if you only need to build a quick-and-easy app for RapberryPi. For these purposes this article lists details about RPi development.

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The smallest Linux for Raspberry Pi?

There are dozens of articles similar to this, so I treat it just as another quick memo for myself:

  1. You can create custom Linux-based system yourself with tools like:
  2. A ready out-of-the box solution is Core Linux / pi Core:
    • some info: here, here and here
    • very modular, add whatever you need
    • smallest version is claimed to have only 10 MB with GUI!
  3. Smallest Rasbian OS is 0.5+ GB in size so is out of option.

And if anything above is not for you then maybe a… non-Linux solution for your RPi?

Developing for Raspberry Pi with Ultibo

Building apps that will be run on Raspberry Pi will require you in most scenarios to:

  • Develop a regular Linux app
  • Optimised to use hardware and computing power of Raspberry Pi
  • Run it in Raspbian OS or any other Linux distribution of your choice

If you:

  • Can’t or don’t want to base your solution on Linux
  • Need to have nearly no limits and full fexibility
  • Want to learn something really cool

Then you need to get your hands dirty, forget about Linux and start thinking about Ultibo.

What the heck is this? Well… to cite its creators (emphasis and shortening mine):

Ultibo is a complete embedded development environment written specifically for creating applications with small single board computers. It uses many concepts from general operating system design and even borrows information from Linux, but Ultibo is not based on anything else.

Yes, it is what it sounds! No Linux, no console (unless you develop one!), no distro installation. Free Pascal (other languages also partially supported), Lazarus IDE (on any platform), and Raspberry Pi as a target (other platforms also partially covered).

And they’ve told us that Delphi and Pascal programming is long gone and forgotten… Ha! :)

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Raspberry Pi-based computer for 80 USD or less?

The variety of original Raspberry Pi editions and thousands of its clones may be a little bit overwhelming.

If you have a problem selecting proper gear box for your scenario or solution this article may help a little bit. I’ll suggest basic components (Raspberry Pi 4’s version, some case and SD card) and a good looking, promising operating system.

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The very introduction to Raspberry Pi

After a nearly five years of struggling with hardware and software for feeding data to Flightradar24, I have finally decided to give it a try with Raspberry Pi. On contrary to what some of you may think, this is not a guide on how to achieve it. The original text is very good and quite self-explanatory. No need to copy it here.

In addition to feeding data to Flightradar 24 there are hundreds of ideas how can you use your Raspberry Pi. With this article I wanted to show you (and remind to myself) just of a few IMHO most interesting ones.

If you’re just unpacking your first Raspberry Pi then better read these two articles:

before even continuing with this article.

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