I'm not able to enable the Raspberry Pi's VNC capture mode from the command line.
ExperimentalRaspiCapture mode allows you to remotely view videos running.
If not enabled, you cannot watch videos. As my application has disabled the raspbian graphical mode, I only have operations from the command line and I do not have access to the internet on them, only local network.
I did tests on an alternative raspberry and in graphical mode I enabled this option according to the tutorial on page vncserver experimental direct capture mode missing and it worked for me, but I have several raspberries and enabling it by command line is my best option at the moment, but I can't enable it.
I already tried the tutorial on the page:
How do I get VNC access to Kano OS working correctly?
But it did not work.
Any idea? Has anyone managed to do this?
Thanks.
Use vnc version: VNC (R) Server 6.2.1 (r32538) ARMv6
I use the raspberry:
*Linux raspberrypi 4.14.34-v7 *
I found the problem. I wasn't doing it right. I have to change the file in the root user and then restart the serviced. ;)
Edit the config file '/root/.vnc/config.d/vncserver-x11'
adding the following:
CaptureTech=raspi
ExperimentalRaspiCapture=1
ServerPreferredEncoding=JPEG
and then restarted:
sudo systemctl restart vncserver-x11-serviced
Related
I am trying to use VNC in a headless install on my Raspberry Pi 4, running Raspberry Pi OS, installed via Raspberry Imager. The install is more or less vanilla, as the only changes I have made are for connecting (seting up SSH, wireless and VNC as noted in this guide: https://www.tomshardware.com/reviews/raspberry-pi-headless-setup-how-to,6028.html).
When I log in via VNC I get the "Cannot Currently Show the Desktop"-error. It should be possible to fix by changing the screen resolution via raspi-config, but that makes the pi unresponsive. Setting the pi to use "G3 legacy" should fix that issue either after a reboot or without (answers vary on that), but it doesn't seem to make a difference in either case.
Does anyone know how I can get to connect via VNC to my pi?
Thanks :)
According to the documentation:
If your Raspberry Pi is headless (i.e. not plugged into a monitor) or
controlling a robot, it is unlikely to be running a graphical desktop.
So the idea is to create a new virtual desktop via vncserver command and use the display number in VNC.
Basically should be sufficient to specify a HDMI mode. I have a Raspberry Pi4 headless, this is my configuration in /boot/config.txt
# For more options and information see
# http://rpf.io/configtxt
# Some settings may impact device functionality. See link above for details
# uncomment if you get no picture on HDMI for a default "safe" mode
#hdmi_safe=1
# uncomment this if your display has a black border of unused pixels visible
# and your display can output without overscan
disable_overscan=1
# uncomment the following to adjust overscan. Use positive numbers if console
# goes off screen, and negative if there is too much border
#overscan_left=16
#overscan_right=16
#overscan_top=16
#overscan_bottom=16
# uncomment to force a console size. By default it will be display's size minus
# overscan.
#framebuffer_width=1280
#framebuffer_height=720
# uncomment if hdmi display is not detected and composite is being output
hdmi_force_hotplug=1
# uncomment to force a specific HDMI mode (this will force VGA)
hdmi_group=2
hdmi_mode=82
# uncomment to force a HDMI mode rather than DVI. This can make audio work in
# DMT (computer monitor) modes
#hdmi_drive=2
# uncomment to increase signal to HDMI, if you have interference, blanking, or
# no display
#config_hdmi_boost=4
# uncomment for composite PAL
#sdtv_mode=2
#uncomment to overclock the arm. 700 MHz is the default.
#arm_freq=800
# Uncomment some or all of these to enable the optional hardware interfaces
dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on
# Uncomment this to enable infrared communication.
#dtoverlay=gpio-ir,gpio_pin=17
#dtoverlay=gpio-ir-tx,gpio_pin=18
# Additional overlays and parameters are documented /boot/overlays/README
# Enable audio (loads snd_bcm2835)
dtparam=audio=on
[pi4]
# Enable DRM VC4 V3D driver on top of the dispmanx display stack
dtoverlay=vc4-fkms-v3d
max_framebuffers=2
[all]
#dtoverlay=vc4-fkms-v3d
gpu_mem=128
start_x=1
enable_uart=1
#hdmi_enable_4kp60=1
Then I disabled encryption and set a VNC password. In addition, if you to see the raspistill/raspivid preview through VNC you have to enable this: RealVNC Viewer > Menu > Options > Troubleshooting > Optimize screen capture - select 'Enable direct capture mode'
Raspbian Buster:
Launch command line and run:
sudo raspi-config
Display options -> Resolution. Then select a resolution mode, I recommend select 1280x720 but you can also choose the higher resolution (1920x1080). Save and finish.
Reboot and connect to raspberry again through VNC client.
Raspbian Bullseye:
Launch command line and run:
sudo raspi-config
Display options -> VNC Resolution. Then select a resolution mode, I recommend select 1280x720 but you can also choose the higher resolution (1920x1080). Save and finish.
Reboot and connect to raspberry again through VNC client.
This solved the problem for me: https://www.shellhacks.com/raspberry-pi-force-hdmi-hotplug/.
TL;DR
Setting the resolution of VNC in Raspberry Pi (RPi):
/usr/bin/xrandr --fb 1920x1080
Long answer
One can examine the code of raspi-config bash script, here
Look for the do_vnc_resolution function.
My Rpi4 Bullseye machine had set itself into safe mode … in /boot/config.txt the line
hdmi_safe=1
Was uncommented.
Commenting it out fixed my lo-resolution VNC display problem
Then had to reboot, then logout, and login for everything to be set ok
I have an embedded board with an STM32 microcontroller, and an ST-Link v2. This setup generally works: I can program the flash, and connect with ST's CubeProgrammer tool or with openocd. I can attach gdb to the latter, and step through code. So far, so good. It does not appear there is any problem with my physical or electrical setup.
I have a program which is... not so good. Something early in initialization is hanging up the chip to the point where I can no longer connect to it with any tools. I can rescue it by using the "Under reset" mode of CubeProgrammer, holding the reset switch on the board at boot, then connecting before the bad program can wedge the chip.
After connecting this way, the chip is halted. I can flash a known good program. Or, I can use the MCU core screen of CubeProgrammer to "Step" one instruction at a time through the bad program's startup. That works, until I hit "Run", and then I quickly get a dialog "Warning: Connection to device 0x411 is lost", and the chip is no longer usable until I flash it as above. It appears the code is configuring the necessary pins into the alt mode to enable serial wire debugging, so I don't think that's the problem, but it's hard to verify.
So, it appears something in this program is behaving badly. What I'd like to do is set up gdb via openocd to debug startup. With a good program, I can connect with openocd while the program is running, attach gdb, and everything works normally. But I don't know how to get openocd to do what CubeProgrammer does with the "Under reset" mode, so I can execute initialization of the chip under gdb control.
How can I do this? Or, is there some other tool I should be trying than openocd+gdb? I'm familiar with gdb, but I can try other tools. The host environment is macOS.
Create an openOCD config file like this:
#
# stlink to stm32f2xx by swd with system reset and no test reset
#
source [find interface/stlink.cfg]
transport select hla_swd
source [find target/stm32f2x.cfg]
reset_config srst_only connect_assert_srst
And use the -f flag to openOCD to use it.
I'm currently busy with my masters project which involves setting up comms on UART between a Raspberry Pi Model 2 B V1.1 and a Pixhawk Flight Controller using Mavlink protocol.
The first step is, of course, to get the UART set up and working. I'm not one to run after help at the first sign of a problem. I have been struggling with this for days and it's forced me to doubt the purpose of my existence more than once. I feel stupid and frustrated. Please see if you can provide any assistance.
My first resource was this tutorial, which should be relatively straight forward:
http://ardupilot.org/dev/docs/raspberry-pi-via-mavlink.html
The tutorial simply installs all the necessary packages and dependencies, as well as sets up the UART. I followed the steps to disable OS use of the serial port through raspi-config, however after attempting to test the connection I get an error:
[Errno 2] No such file or directory: '/dev/ttyAMA0'
Which is very strange. So after disabling and enabling OS use of serial port through rasp-config a few times and checking, every time I disable it, the /dev/ttyAMA0 file disappears. Now how the hell is anything supposed to work on the UART if disabling OS use of the UART removes that file!? Nevertheless I powered through. I enabled OS use of the serial port, which leaves the ttyAMA0 file right where it is and followed another suggestion, which is to change the /boot/cmdline.txt and remove all reference to ttyAMA0, as shown in the following link:
http://www.raspberry-projects.com/pi/pi-operating-systems/raspbian/io-pins-raspbian/uart-pins
This seemed to work alright. I could now initiate comms between the RPi and the Pixhawk flight controller and get some information that looked correct. Then the black magic started. The next day I tested the connection and it consistently spat out complete rubbish. But Nothing changed since the previous day. Somewhere I must be missing something. I followed all the same tutorials and steps attempting to get the more positive results I got the previous day. However that only led to more erratic behaviour. When connecting the serial lines to my Pixhawk Flight Controller, the keyboard/mouse seems to get interrupted momentarily every now and then. Everything just went backwards. I have already reinstalled Raspbian Jessie in a desperate attempt to get things to work.
Here are a few things I suspect could possibly contribute to the problems:
Baud rate not correct (to communicate with my Flight Controller baud rate needs to be 57600). Best way I've found to set this baud rate is to append "init_uart_baud=57600" to /boot/config.txt/. I have also read about other ways such as appending a line to /etc/crontab. Any suggestions?
Pixhawk miraculously and sporadically refused to communicate back with RPi.
Any assistance will be appreciated. Thank you.
SOLVED:
Looks like a known bug in the latest raspbian, easy to fix though.
These need to be done as the root user.
Disable "serial console" through GUI-preferences or "sudo raspi-config." Then reboot the pi.
Then change the following line in the file /boot/config.txt at the bottom of the file from:
enable_uart=0
to
enable_uart=1
Disable the ModemMonitor service by running the following command as root:
systemctl disable ModemManager.service
Then add youself to the dialout group, just to be sure you have the required permissions on the serial port:
adduser pi dialout
That should give you unrestricted proper access to the serial port.
Resources:
[url]https://www.raspberrypi.org/forums/viewtopic.php?f=66&t=148515[/url]
and
[url]https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=82779[/url]
I had researched this for days now and troubleshooting all the readings listed on Google sites. I solved the serial UART settings for connecting my RPi3 Model B (typed at command line the following:
`cat /proc/cpuinfo`
to find my Pixhawk hardware info.)
FYI: You must be root when working with mavproxy so, sudo su
or sudo -s
Also, you must be a member of the dialout group, so do this at CMD line:
sudo usermod -a -G dialout root (enable root user!)
Do all the RPi regular stuff:
sudo apt-get update && sudo apt-get upgrade and sudo rpi-update.
Did all as outlined in the Ardupilot website. I did NOT use the
"apsync-rpi". (I used the 2017-03-02-raspbian-jessie.img.) at here
On my RPi3, using $uname -a: results--> Linux raspberrypi 4.4.50-v7+
My $sudo nano /boot/config.txt file has one change at bottom of file;
THIS statement: enable_uart=1 (has a good side effect of forcing the
core_freq to 250 which reduces poor signal frequency)
Important discovery: so the articles state that RPI3 UART and tty settings have changes. (link here)
What I have discovered after much ado is this for my sudo nano /boot/cmdline.txt file:
dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 etc.,.
-Notice I am not using ttyS0 in the /boot/cmdline.txt file. I tried the ttyS0 a dozen times and it never worked properly. For some reason, I am not able to explain it at this time, although the console=/dev/tty1 works if written in the /boot/cmdline.txt file.
Make sure you have the wiring correct between your RPi and the Pixhawk.
Telem 2. Also set the correct parameters in Mission Planner as I
have;
Go to CONFIGTUNING->STANDARD PARAMS; (my settings)
-The Serial0 baud rate(SERIALO_PROTOCOL) is: 115200
-The Console protocol selection(SERIAL0_PROTOCOL) is: MAVlink1
-Telem1 baud rate(SERIAL1_BAUD) is at: 115200
-Telem1 protocol selection(SERIAL1_PROTOCOL) IS MAVlink2
-Telemtry 2 Baud rate(SERIAL2_BAUD) is 921600
-Telemetry 2 protocol selection(SERIAL2_PROTOCOL) is MAVlink1
The RPi and pixhawk communicate at 921600 baud rate.
-Once I get the RPi3 powered up with it's own +5/VCC source and connect to my MP with a 3.0 USB cable from my PC-Windows10PRo, (okay, I have Arch and Debian Linux distros and Apple OSes too!) I enter:
`mavproxy.py --master=/dev/ttyS0 --baudrate 921600 --aircraft Plane`
It works for me!
Happy experimenting and flying!
I'm setting up some new VNC servers. I already have this setup working with CentOS 6.3, although I'm not certain that this difference is the real problem.
One of the window managers I'm making available is fluxbox, but when I start it, I always get the following: Error: Couldn't connect to XServer. Here's my setup:
fluxbox: fluxbox-1.1.1-5.el6.x86_64
vnc : tigervnc-server-1.1.0-5.el6_4.1.x86_64
OS : CentOS 6.4
Note that I can start other window managers: Gnome, KDE, openbox, xfce4, etc.
I gutted my ~/.vnc/xstartup script so it only loads an xterm. Then, I tried running startfluxbox &, but still got the error. Obviously, VNC is working, since my xterm opened up OK. I can start firefox, another xterm or other app requiring X, and even fluxbox comes up, but it is worthless in its current state, since it is not connected to the X session.
What is fluxbox looking for? Are there some log files I can look at to give me some clues?
Thanks,
David
CentOS/RHEL 6.4 and up have upgraded libX11 and Xorg.
The $DISPLAY var handling has changed in libX11.
This one in particular is described in this git commit:
http://cgit.freedesktop.org/xorg/lib/libX11/commit/?id=f92e754297ec5fdb81068b56a4435026666224fa
we run our fluxbox with this script in our vnc configs now:
/usr/bin/fluxbox -display "$DISPLAY.0"
OK, I think I've figured out the problem, so I'm answering my own question.
In VNC, I usually specify a display number. (Note, however, that the problem occurs even if vncserver uses the first available display number.) So, I start the vncserver as:
vncserver :17
This should create an X session where my $DISPLAY is set to :17.0, but in CentOS 6.4, the $DISPLAY is set to :17 instead. Apparently, unlike other window managers, fluxbox is unable to handle this inaccuracy. The problem, then, was that fluxbox was trying to connect to :17 and was unable to do so.
My solution, as suggested by someone answering a different problem, was to set $DISPLAY as part of the invocation of fluxbox. So, in my ~/.vnc/xstartup file, I have:
DISPLAY=$DISPLAY.0 startfluxbox &
Note that this may not work for other releases of CentOS, so you might wish to test the release of the box you are using before adding the DISPLAY=... setting to the command.
I'd like to start service before user mode is loaded (in kernel mode).
The reason is I wanna run several system applications(asm code to write data to BIOS) that are not allowed in user mode (privileges problem).
That's why I got an idea: 1. Write windows service 2. Start and run it in kernel mode
Is it possible?
Are there any other ways to solve the problem?
I don't usually use Vista (use linux instead), that's why I'm asking.
Windows services are user-mode applications. To run in kernel-mode you should write a driver. (So-called "legacy" driver will be enough, see Driver Development Part 1: Introduction to Drivers).