Archive for the ‘raspberrypi’ Category

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Scanning the WiFi network with the Raspberry Pi Pico W

Friday, July 22nd, 2022

Let’s try the Wifi features of the new Raspberry Pi Pico W.

The Pico W has two Wifi interfaces:

  • network.STA_IF, the station interface
  • network.AP_IF, the access-point interface

network.STA_IF

The station (or standard) interface, can be used to connect the Pico W to another 2.4GHz WiFi access point. This seems to be the default.

network.AP_IF

The access-point interface can be used to turn your Pico W into a WiFi access-point that can connect up to 4 devices at the moment.

Use the Pico W to scan access points

Let’s try out the station interface, network.STA_IF.

Using micropython it’s really a breeze:


import network
import binascii
wlan = network.WLAN() #  network.WLAN(network.STA_IF)
wlan.active(True)
networks = wlan.scan() # list with tupples with 6 fields ssid, bssid, channel, RSSI, security, hidden
i=0
networks.sort(key=lambda x:x[3],reverse=True) # sorted on RSSI (3)
for w in networks:
      i+=1
      print(i,w[0].decode(),binascii.hexlify(w[1]).decode(),w[2],w[3],w[4],w[5])

In most example code you need to specify the interface, but apparently it defaults to the standard station network.STA_INF interface.

The output is a list with tupples that according to the docs should contain six fields ssid, bssid, channel, RSSI, security, hidden.

The bssid is the same as the hardware unique MAC-address.

There are five values for security:

  1. open (0)
  2. WEP (1)
  3. WPA-PSK (2)
  4. WPA2-PSK(3)
  5. WPA/WPA2-PSK (4)

and two for hidden:

  1. visible (0)
  2. hidden (1)

The docs states that for hidden 0 = visible and  1 = hidden, but actually the output I get, some twenty networks(!?) gives no 0, but several undocumented values for hidden: 1,2,3,4,5,7.

Twenty WiFi-networks? Yes, I do work in a city. And that’s only the 2.4GHz band. 🙁

So what does those values mean, what is there more than visible or hidden?

Also the security results differ with outputs from 0 (=open), most 5, but some report 7.

What do those values for security mean?

Is it a bug or a (undocumented) feature?

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Raspberry Pie with a Taste of Chocolate, the funny Desktop Droste effect

Tuesday, June 28th, 2022

The original Droste Effect

Trying out the new Ubuntu 22.04 on my Raspberry Pi 400, I was surprised by the smoothness of the new Ubuntu distribution. Much better impression then the first time I tried Ubuntu on the RPI, I think that was the 20.10 release.

A funny thing to try out, especially if you love fractals or you are an admirer of the Dutch graphic artist Escher who’s work features features mathematical and even impossible objects, is the subject of this post.

Another returning phenomenon in his drawings and paintings is the Droste-effect , and I’ll shwo you how to create a Droste effect on your Raspberry Pi with a few mouse-clicks.

Creating a Droste effect on your Raspberry Pi

Yes, you can do that with just a couple of mouse-clicks, you don’t need a mathematical package or a graphical editor like Gimp or so.

Trying out the new Gnome Desktop Sharing feature, which let you share your desktop not only with the older VNC protocol, but also with the newer RDP protocol, gave me this idea.

To activate:

Settings -> sharing -> enable -> enable Remote Desktop -> and setup some authentication: username and password

For creating the Droste-effect we gonna do something silly: we gonna connect to our-self! Yes a Remote Desktop Connection with a local client.

A Remote Desktop Connection with a local client

Introspection!

Start up the default remote desktop client Remmina.

Quick setup a new connection, enter your IP-address and the authentication you just entered: username and password.

To find your IP-address, open a terminal, (CTRL ALT T) and type `ip address` return. Then you will find it in the output, or look it up under details in the network settings.

Save and connect in the Remmina dialog, and see the connection being made.

Click the `Toggle Scaled Mode` button to rescale the desktop (CTRL_R S), and there it is.

A nice Raspberry Pi Droste Effect of the Ubuntu Desktop in a local remote Desktop connection: 🙂

Remmina Droste effect

Remmina Droste effect

Gnome-connections

An alternative to `Remmina` is Gnome-connections. That program is in development, but like all Gnome apps, it does offer an very easy and intuitive approach.

Can all the settings in Remmina be overwhelming, gnome-connections is easy as it can be.

But the default resolution seems to be quite poor. And I could not find a scaling options, so you end up with a more spacey psychedelic form of computer art.

The Gnome-Connections Art

The Gnome-Connections Art

Cool as well.

Update: Actually there is a scale setting for Gnome-Connections, a bit hidden, under properties once you established a connection. Using Gnome-connections for managing my Pi400 from another Ubuntu 22.04 is working quite well, although I had to restart the Pi400 to get control working.

So maybe Gnome-connections is lacking a lot of settings, it’s working out of the box surprisingly well in Ubuntu 22.04.

Give it a try, if you own a Pi.

How does the Pi create a Droste effect?

You open up a program that shows your complete desktop scaled including the program that shows your desktop scaled, etc etc.

Actually I was expecting a crash, or out of memory error, you will probably get that when you let it run for hours, but the Raspberry Pi kept being responsive for the couple of minutes I tried. Enough time to take a screenshot.

So it seems Ubuntu and Gnome are much more optimized for running on less powerful hardware in 2022 then a couple of years ago.

This funny showcase of the Droste-effect is the prove, and that is all a big win.

Please let me know what you think in the comments.

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Kodi on Bullseye, playing 4K on the RPI4

Friday, March 18th, 2022

Getting the most out of your (cheap) hardware is always a challenge. Selling hardware is easier then supporting hardware.

The Raspberry Pi 4 has strong multimedia capabilities, it can playing 4K media 60fps, but getting it done isn’t a piece of cake. Even playing 1080HD content on YouTube can be a problem, but that’s probably because YouTube is more about tracking and selling adds than playing media.

A bold statement? Think about it this way. Any 1080p movie will play fine outside a browser in Kodi, any movie will play fine without DRM (Digital Rights Management). It chokes on the DRM en-/decryption. By definition: DRM is tracking.

Historically LibreElec is the best distribution for a Raspberry Pi as a multimedia device. LibreElec’s goal: just enough OS to support Kodi, and it is highly optimized for that.

Yes it’s powerful. You can install add-ons like MPD for music, or RetroPie-alike  for games. Also docker containers are available for HomeAssistant, MQTT and Nginx. So a RPI with LibreElec can be pretty powerful.

Still LibreElec is limited, and the RPI4 is capable of doing more.

Kodi on Raspberry used to work pretty well, until big changes in the 5.10 kernel came. It more or less stopped working on Buster. Compiling it yourself was quite a hassle, that actually failed more than it succeeded. I wrote about that before and it failed in most cases for most users including myself, I must admit.

But now luckily RPI-engineers stepped up:  Kodi in Rapsberry Pi OS is more or less supported again.

At least it’s easy again to install Kodi in Bullseye. But you still need a bit more tweaks to get it running smoothly.

To install Kodi in Bullseye

No OS can beat this 🙂 :

sudo apt install kodi

Install addons

Two important add-ons that can’t be installed from within Kodi like in LibreElec, but you have to resort to apt again:

TVHeadend-client (DVB-T tv)

sudo apt install kodi-pvr-hts

Only the client is installed with this command, this assumes a TV-Headend server is running on another local IP-address.

Inputstream-adaptive helper to play DRM protected (Widevine) content

sudo apt-get install kodi-inputstream-adaptive

The add-on then will extract (and update) the needed libs from internet automatically.

To enable HEVC HW decoding, you have to tweak /boot/config.txt

Add this line (only for RPI4)

dtoverlay=rpivid-v4l2

For 4K HEVC playback tweak this line:

# Enable DRM VC4 V3D driver
dtoverlay=vc4-kms-v3d,cma-512

Mount NFS shares

Somehow Kodi on Bullseye stopped discovering NFS by default. Don’t worry to much, just give it a little manual bump.

  • Choose Browse for new share -> Add network location -> Protocol -> Network File System (NFS)
  • Entering the your ip-address as Server address and Remote path manually, adding up to something like nfs://192.168.0.3:/path/to/mnt/
  • Click OK, then it will list.
  • Select and click OK.

Conclusion

Changes in `/boot/config.txt` require a reboot.

After all these steps, playing 4K HEVC content with HW-acceleration should work fine on a Raspberry Pi 4.

That’s all. Let me know if it’s working for you.

 

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Powering a Pi Zero (2) from your laptop

Friday, November 12th, 2021

The new quad-core Pi Zero 2 has a lot more horsepower than the original Zero and as a consequence it does require more power than the original Zero.

But that doesn’t necessarily means that you cannot power it from an USB port from your laptop.

Can you still power a Raspberry Pi Zero from an USB port of a laptop?

Let’s try. Be reminded all Pi’s are cleverly designed to throttle down, when they experience a power shortage.

To check if your Pi has throttled down:

> vcgencmd get_throttled
throttled=0x0

If you see some other output then 0x0 yes then you’ve had power problems. Otherwise you’re OK.

For the moment, running Raspberry Pi OS Bullseye on a Raspberry Pi Zero 2 powered form an USB port doesn’t show problems by just installing programs and updating the OS.

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No display after update to LibreElec 10.0.1 on a Raspberry Pi 4

Tuesday, November 9th, 2021

Last weekend I did an upgrade on my Kodi/LibreElec 10.0.0 RPI4 to 10.0.1.

All went well initially, I also did a firmware upgrade, but after rebooting I got a blank screen.

For a moment I thought Kodi didn’t boot at all, but on my Kore remote app, I saw that it was connected.

Also I could hear the GUI sounds. I disconnected my monitor, tried different HDMI inputs and different settings on the monitor. To no avail. Rebooted my Pi again. Shut it down, disconnected the power, connected it again, and rebooted. Still a blank screen. Could see the blown up pixel for a while, but blank screen afterward.

Still I could hear the GUI sounds, and I could even start a DVB-T TV channel.

So Kodi was working, but there was no HDMI output! Then intuitively I changed the audio-output from IQAudioDAC to HDMI and suddenly it started working! I changed it again to IQAudioDAC and screen output kept working.

And it did since!

Somehow changing the audio output fixed the blank screen output on my Raspberry Pi 4. Weird.

And don’t ask me why, but I’m still happy with this LibreElec / Kodi setup on my Raspberry Pi 4.

Changing Audio output remotely on Kodi

To change the audio output for Kodi remotely, instead of using the GUI or the Kore remote app and a lot of clicks, you can use these commands from another PC or phone:

Change to HDMI

curl -v -H "Content-type: application/json" -d '{"jsonrpc":"2.0","method":"Settings.SetSettingValue", "params":{"setting":"audiooutput.audiodevice","value":"PI:HDMI"},"id":1}' http://yourpi.local:8080/jsonrpc

Change to analogue

curl -v -H "Content-type: application/json" -d '{"jsonrpc":"2.0","method":"Settings.SetSettingValue", "params":{"setting":"audiooutput.audiodevice","value":"PI:Analogue"},"id":1}' http://yourpi.local:8080/jsonrpc

 

Remember to change the domain/hostname ot an IP-address if you wish to run the command from your Android phone.

Above commands work great as Termux Widget shortcuts on your Android Phone.

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Playing 4K smoothly on the Pi4, compiling Kodi 19 on Raspberry Pi OS

Thursday, June 24th, 2021

Kodi is the best software to watch video on a Raspberry Pi. The Raspberry Pi 4 supports 4K, but the only software that can play it well is Kodi. That’s a bit disappointing, knowing the the Pi4 is already available since early 2019.

On the other hand, Kodi is nice open source software, with a thriving community.

Playing video in a browser is energy-wise, (privacy-wise IMHO) and performance-wise a bad thing. Try playing YouTube movies in a browser and in Kodi (unofficial YouTube plugin), and see the differences. Stuttering play, and high CPU usage in the browser, smooth play and lower CPU usage in Kodi.

The best performance for Kodi is offered by LibreELEC, a lightweight ‘Just enough OS’ Linux distribution. if you wanna run the latest Kodi on Raspberry Pi OS, you’ll need to compile it yourself at the moment.

Compile instructions Kodi 19

There isn’t yet an updated version Kodi 19 in Raspberry Pi OS, so you’ll need to compile Kodi 19 yourself. Big underlying changes in the way video and hardware-accceleration is done in the new kernel 5.10 broke Kodi 18.7 and

On the Kodi forum there are several attempts to compile a working version, but apparently that is not so simple. Still I used those instructions as a base, but added the kernel-header packages ` as a dependency and use a patched version of Kodi.

# sudo apt update && sudo apt full-upgrade -y


sudo apt install                                                     \
autoconf automake autopoint autotools-dev cmake cpp curl default-jre \
g++ gawk gcc gdc gettext git gperf libasound2-dev libass-dev             \
libavahi-client-dev libavahi-common-dev libbluetooth-dev             \
libbluray-dev libbz2-dev libcdio-dev libcec4 libcec-dev              \
libcrossguid-dev libcurl4-openssl-dev libcwiid-dev libdbus-1-dev     \
libdrm-dev libegl1-mesa-dev libenca-dev libflac-dev libfmt3-dev      \
libfontconfig-dev libfreetype6-dev libfribidi-dev libfstrcmp-dev     \
libgbm-dev libgcrypt-dev libgif-dev libgles2-mesa-dev libglew-dev    \
libglu1-mesa-dev libgnutls28-dev libgpg-error-dev libgtest-dev       \
libinput-dev libiso9660-dev libjpeg-dev liblcms2-dev liblirc-dev     \
libltdl-dev liblzo2-dev libmariadb-dev libmicrohttpd-dev libnfs-dev  \
libogg-dev libomxil-bellagio-dev libpcre3-dev libplist-dev           \
libpng-dev libpulse-dev libshairplay-dev libsmbclient-dev            \
libsqlite3-dev libssl-dev libtag1-dev libtiff5-dev libtinyxml-dev    \
libtool libudev-dev libunistring-dev libva-dev libvdpau-dev          \
libvorbis-dev libxkbcommon-dev libxmu-dev libxrandr-dev libxslt1-dev \
libxt-dev lsb-release meson nasm ninja-build python3-dev python3-pil \
python-support rapidjson-dev raspberrypi-kernel-headers swig unzip \
uuid-dev wayland-protocols yasm zip zlib1g-dev

Then you need a special GBM version of Kodi, but instead of this version.

wget https://github.com/popcornmix/xbmc/archive/gbm_matrix.zip

I used a patched version:

wget https://github.com/graysky2/xbmc/archive/refs/heads/gs-gbm_matrix.zip

Then this workaround is needed, Raspberry Pi OS uses a different path for some files. This just creates a symbolic link to the right path.


# drm_fourcc error workaround
sudo mkdir /usr/include/drm/ 
sudo ln -s /usr/include/libdrm/drm_fourcc.h /usr/include/drm/drm_fourcc.h

Extract the downloaded zip:

unzip gs-gbm_matrix.zip

Enter the map

cd xbmc-gs-gbm_matrix

Create build directory:

mkdir kodi-build

Enter build directory

cd kodi-build

Then make:

cmake .. -DCMAKE_INSTALL_PREFIX=/usr/local -DCORE_PLATFORM_NAME=gbm -DAPP_RENDER_SYSTEM=gles -DX11_RENDER_SYSTEM=gles -DENABLE_INTERNAL_FMT=ON -DENABLE_INTERNAL_FLATBUFFERS=ON -DENABLE_INTERNAL_SPDLOG=ON -DENABLE_VAAPI=OFF -DENABLE_VDPAU=OFF

Then compile

cmake --build . -- VERBOSE=1 -j$(getconf _NPROCESSORS_ONLN)

If done properly, ti should take about 2 hours. Afterwards you can start Kodi with `kodi-build/kodi-gbm`

That’s all. And don’t forget to backup your existing Kodi profile.

Occasionally the script exits with an error. Seems it’s running out of memory. Just restart the building process, executing the cmake –build command, to finish compiling.

UPDATE:

For Raspberry Pi Bullseye see this new post: