Posts Tagged ‘rpi’

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Fixing the annoying rsync auto-completion bug with path containing spaces

Tuesday, December 5th, 2023

Experimenting with a Raspberry Pi 5, I tried to sync some files from the Pi to my Ubuntu 22.04 Desktop.

Once you have setup ssh-keys with ssh-copy-id, and added an entry to .ssh/config you can easily connect to your pi with

ssh pi

using rsync on the Raspberry Pi

Copying a file or directory can be done with rsync:

rsync pi:pathtofile/file.txt .

Now the file will be copied to your working directory (directory your running the command from)

rsync will magically autocomplete the path in the same way it does for local path by pressing tab.

I have a dir called `new map` on my pi. It contains a space.

When I type `rsync pi:new` and press TAB rsync will auto-complete it to `rsync pi:new\\\ map`

It will double-escape the path.

But executing the command after auto-completion does not work:

rsync pi:new\\\ map .
rsync: [sender] link_stat "/home/pi/new\ map" failed: No such file or directory (2) 
rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1865) [Receiver=3.2.7] 
rsync: [Receiver] write error: Broken pipe (32)

Using spaces in maps of file-names is a nasty thing that should be avoided. Sooner or later it will give you troubles.

As it seems newer versions of rsync (> 3.2.4) do NOT require double escaping anymore, but the auto-completion still uses it.

This is clearly a bug:

https://github.com/scop/bash-completion/issues/848

Use the –old-args argument for rsync to fix auto-complete double escaping

The workaround is to use the –old-args argument for rsync

rsync --old-args pi:new\\\ map

Now it is working fine, I suppose this will be fixed in a newer version of rsync.

 

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Controlling the Fan of the Raspberry Pi 5 in Ubuntu 23.10

Thursday, November 9th, 2023

The new Raspberry Pi 5 is a really nice upgrade. Both RaspberryPiOS and Ubuntu 23.10 are really running much faster on the new model then on a RPI 4.

Booting RaspberryPiOS takes around 12sec on a ordinary SanDisk SD card. The fan is running full speed at boot, but is slowing down afterwards. And it has not started again during browsing a few websites.

Ubuntu boots a bit slower, but GNOME 3 is also running really fine. Ubuntu is visually more attractive, and it’s really running smooth.

There is a big annoyance for the moment and that is the fan. It is running full speed at boot and keeps running all the time full speed, making to much noise.

Fan control doesn’t seem to work yet, but controlling the fan can be done manually by writing a number in the range 0 (off) to 4 (full speed) to /sys/class/thermal/cooling_device0/cur_state

So I created a startup service that slows down the fan on Ubuntu after boot to speed setting 1, and that is inaudible.

[Unit]
Description=RPI-startup Fan Control service
After=multi-user.target
[Service]
User=root
Type=oneshot
ExecStart=/bin/bash -c "echo '1' | tee -a /sys/class/thermal/cooling_device0/cur_state" &
[Install]
WantedBy=multi-user.target

Copy above content to a file /etc/systemd/system/fan.service.

And enable it by:

sudo systemctl enable fan.service

That’s all, no reboot the Pi and Ubuntu will be silent.

Remember the Raspberry Pi willl automatically throttle when reaching a temperature of 85°. So there is no danger in letting the fan run on speed 1 continuously. Even when your compiling the Linux Kernel.

Off course you can always check the temperature with, and yes that works also in Ubuntu 23.10 on the Pi

sudo vcgencmd measure_temp

You can always bump up the speed to 3 by issuing this in the terminal

echo '3' | sudo tee -a /sys/class/thermal/cooling_device0/cur_state

 

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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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