New answers tagged pi-3
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So I really do not think the issue is with your initial code at all but the real problem is in the way you designed the circuit as you should not connected all sensors to the same trigger pin but to different pins on microprocessor as each sensor can not catch it's own echo that way.
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This is not a complete answer but a suggestion to narrow down the problem. All transfer methods you have used are using the same buffered input/output API of the operating system so it shouldn't make a difference. To test low level direct writing of random data without using buffered I/O you can use dd assuming disk partition /dev/sda2 is mounted at /mnt/p2/:...
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Short answer is "you can't" as the 4-20mA current loop is an analogue signal and the Pi does not have any direct analogue inputs. You can, however, add a device called an Analogue to Digital Converter (ADC) to your Pi that will let you then take analogue measurements.
Typically you'd "drop" the current loop output of you sensor across a 100 or 120 Ohm ...
1
pigpio has a more deterministic response to GPIO level changes.
Try my pigpio Python example.
It requires the pigpio daemon.
sudo pigpiod
If Python can't keep up you will have to use C instead. Perhaps try this pdif2 C example. It also use the pigpio daemon.
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One idea is to handle transitions on the server. Give your clients a single endless video stream to play, and push data from different files in that stream. That's how info-beamer seems to work. I think VLC should be able to push a complete playlist to an HTTP stream as well, but I haven't tried it myself.
Of course, streaming only works while you're online....
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I should point out that while M. Rostami's answer will likely work if you haven't installed the heat sinks on your Raspberry Pi 3 B, with the heat sinks, I suspect it will not work. The second layer of plastic case in the case does not have a cutout to let the heat sink grill go through. And while you can likely cut the necessary holes, you may have ...
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As I suspected, the problem was not because of nat or subnetting but because of wrong ip routes. I explained the solution here:
https://unix.stackexchange.com/questions/566508/correct-routing-of-ipv6
Short answer: Make sure all your devices are routing the traffic for the global ipv6 addresses to their respective local ones.
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Last weekend I took a project to build myself a nice Pi powered NAS. Everything worked perfectly, but as I saved my changes to /etc/fstab and rebooted all hell broke loose. The Pi would simply not boot up. I run almost all my Pis in a headless enviroment so I had to get hold of our TV and a keybaord to see what was going on.
Lo and behold, there it was, The ...
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Answer
Yes, I would recommend Orca which is now supported on Rpi3/4 buster release 2020feb05. JAWS and NVDA are also good, but they are not free.
Update 2020feb12
Raspberry Pi's Raspbian gets new features: File manager, Thonny updates, Support for Orca - Liam Tung 2020feb11
...
This Raspbian release brings accessibility improvements to the desktop in ...
2
In what way did the following fail?
sudo apt install dolphin
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I resolved the problem. It was a misconfigured /etc/fstab file. For whatever reason, the pi refuses to boot when there is an error in this file. I was able to repair the problem by mounting the SD card on a different Linux machine and edit /etc/fstab there. I only managed to figure it out by borrowing a monitor and seeing the messages displayed during ...
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I tried my RetroPie machine today, and realized that it has similar problems, no connection on Ethernet.
I have a switch attached to the router (so the local network can alive without switch). At the switch, the plug of the Ethernet cable, which comes from the router, was a half millimeter off from the socket. Yes, its picker (what-its-name, it should hold ...
2
For Raspberry PI 4 B and Ubuntu 19.10, if you have black borders above and below:
vi /boot/firmware/usercfg.txt
Add the following line:
disable_overscan=1
Reboot.
0
With Raspbian, network interfaces are managed with dhcpcd by default. If you want to start interfaces manually then you should first disable its service with:
rpi ~$ sudo systemctl disable dhcpcd.service
rpi ~$ sudo systemctl reboot
This ensures that the interface isn't started on boot first and then disabled by a job. You can start an interface with:
rpi ...
0
You can simply disable an interface by running sudo ifconfig eth0 down and also enable that by sudo ifconfig eth0 up.
If you concern that it would be disabled after startup/booting up, you have to make a special service and enable startup that.
Also you can add the command to crontab by:
crontab -e
And put this line there:
@reboot ifconfig eth0 down ...
2
You may not run the latest version of Raspbian which is "Buster". I just tested and installed it without any problem.
However, try to install it manually if it doesn't work anyway:
wget http://ftp.us.debian.org/debian/pool/main/libs/libserial/libserial-dev_0.6.0~rc2+svn122-4+b11_armhf.deb
Then:
dpkg -i libserial-dev_0.6.0~rc2+svn122-4+b11_armhf.deb
...
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It's really time to use Raspbian Buster now. Jessie is deprecated and since beginning of this year it has finished support from Debian. On my Raspbian Buster repository I find:
rpi ~$ apt list libserial*
libserial-dev/stable 0.6.0~rc2+svn122-4 armhf
libserial-doc/stable 0.6.0~rc2+svn122-4 all
libserial0/stable 0.6.0~rc2+svn122-4 armhf
libserializer-java/...
1
You connect pin 12 SCL and pin 13 SDA in parallel to RPi pin 3 SCL & pin 5 SDA.
So the MCP23017 are daisy chained.
You can run up to eight in parallel by setting the A0/A1/A2 pins to a different 3-bit binary value on each MCP23017.
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Always have multiple known good quality power supplies, and good cables (high current rated, and preferably short) , and try several of them first.
Also know that power supplies which worked perfectly for year(s) can an do go bad -- they still look like they work in majority in cases, but at higher load their voltage drops below 4.75V even for a shor time, ...
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It is possible that your SD Card gets weak over a long time. The problem is that SD Cards doesn't report read/write errors to the operating system. It could be that you can flash it but then it looses some bits and bytes after some days possibly still the same weak cells so the symptoms are always the same. You should consider to use a new SD Card.
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RPi is also sensitive to voltage at any time below 5V. In addition to quality - this is one reason the official supplies are also about 5.19V.
Even RPi without USB peripherals but under heavy load can pull enough current to "brown out" (to the RPi) the voltage below 5.0 V. A spontaneous reboot is more a sign of voltage supply drops as the RPi will throttle ...
1
Here's a quote from a reply that Logitech gave regarding the power consumption of their webcams:
[On] C310, power consumption can be anything from 50mA idle to all 500mA for streaming video.
It's quite typical for USB 2.0 devices to aim at always being under the 500mA power budget, which is a maximum that a fully compliant device can draw. So I think it'...
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No one is mentioning that the Maximum total USB peripheral current draw on a rpi 3b+ is 1.2A (power requirements)
Having said that your current psu is enough. If the cameras are indeed drawing more than 600mA each (which I really find it hard to believe, unless they are dodgy) you should start exploring the option of a powered usb hub.
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In the absence of any quantitative observations, the community can only guess. What is the current rating for the power supply? Perhaps a power supply with more current can solve the problem if the cameras need more current than what is available.
If only one attached camera does not cause a reset, then, the current (amperage) is in all likeliness the ...
1
You can save all the information about Raspberry Pis on a server with SNMP. At first, let take a look and this network protocol.
What is SNMP?
Simple Network Management Protocol (SNMP) is an Internet Standard protocol for collecting and organizing information about managed devices on IP networks and for modifying that information to change device ...
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There is no way to get a "profile" with exactly the information you want. But you can use different available commands to gather the information into a file. There are many commands and possibilities. Here are only some examples:
rpi ~$ cat /etc/os-release > profile
rpi ~$ ip address >> profile
rpi ~$ iw dev wlan0 info >> profile
rpi ~$ uname ...
1
I started to write this as a comment, but I think it's really the answer to your question.
NOOBS is at least allegedly an installer for Raspbian and other other operating systems. When used to install Raspbian, it introduces some unneeded complexities.
No matter what approach you take, you have work to do. You must 1) Either undo what you've done ...
2
There is a lot of Raspberry Pi 3 B cases but you want a case in which you mount Pi-Fan to that. In this case, open up this link:
TOPmountain Raspberry Pi Case Abs Protective Shell Case for Raspberry Pi 3 with Fan Hole(Black)
This case has a fan hole. To configure the Raspberry Pi for automatically turning on the Fan, follow this link:
Automatically ...
1
As fas as I am aware this is a fairly well known problem with the DHT22 (models such as the DHT11 do not seem to be affected).
After a random amount of time which can vary between seconds and months they stop responding. The only solution I am aware of is a power cycle.
A solution I have used is to power the DHT22 from a Pi GPIO. The GPIO can supply the ...
1
You wrote that the ssh reverse tunnel is up and works well so I do not understand what's the problem. So I will give a short description how I expect it to work.
A ssh reverse tunnel is established for example with:
rpi ~$ ssh -nNT -R <ip_of_ubuntu-server>:8080:localhost:80 username@ubuntu-server
This will make the local port 80 on the RasPi ...
2
Answer
Introduction
I am a PCM1802 24-bit ADC newbie, never used it before. It is a complicated device and its operation needs a long explanation. For now, I am only trying to give quick and dirty short answers to the OP's couple of questions. I hope to give longer answers later.
All newbies wishing to fully understand the answers given here, are ...
0
Raspberry Pi4 UART
The Pi4 has 4 additional UART (uart2-uart5) in addition to uart0/1 on the older Pi (only one of which can be used as they share GPIO).
Functionally these are equivalent to the fully featured PL011 UART on uart0 and can optionally be configured with CTS/RTS.
These can be enabled (by editing /boot/config.txt), but this requires careful ...
16
RPi 3B only has one antenna on board, so yes, it will be shared. Sharing is managed by the adapter firmware which is closed-source. Even if done right, it will not be as good as separate antennas.
You can get a USB dongle for either WiFi or BT (and use that instead of the built-in adapter) to get two separate antennas.
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After changing the code it worked properly.
So I updated here my code as it will definitely help a newbie.
My device is ADAM-4520(485-232 converter), ADAM-4015(6-channel RTD module).
I am interfacing these two devices with my Raspberry Pi 3 with serial (Rx/Tx)pin.
import serial
import time
import struct
s=serial.Serial(port='/dev/ttyS0',
...
5
2020 Answer
No, there is not a "specific" download. All current versions of Raspbian include a 64-bit kernel (kernel8.img).
However, the Raspberry Pis do not, by default, use the 64-bit kernel.
The "official" way to have your Pi boot in 64-bit mode is to add a line arm_64bit=1 to /boot/config.txt. (Just make sure /boot/kernel8.img exists first).
There ...
3
The apt-get update command requires to write some system directories hence you have to run it as a root user. Or, you can run it by other users (such as pi) with sudo before the command.
So:
sudo apt-get update
In addition, if you still get this E: Unable to lock directory /var/lib/apt/lists/ error, you can remove the apt lock file and see if that ...
1
Looks like you're not prefixing the command with sudo. Try sudo apt update instead. You could use sudo apt-get update but it seems that this is no longer the best practice for Raspbian.
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It looks like the answer was that I should be setting hdmi_mode and hdmi_group, rather than fiddling about with the framebuffer_* options. Setting...
hdmi_group=2
hdmi_mode=58
...has things working quite nicely.
1
Running different versions of python is not an issue of the hardware, means version of a Raspberry Pi. It is an issue of the version of the Raspbian distribution. A specific python version is integrated into the distribution with its shared libraries and tested that it runs there without dependency and version problems. Raspbian Stretch comes with python 3.5,...
1
Look into the Specs section:
PowerIQ Output: 5V=6A(2.4A Max Per Port)
USB PD Output: 5V=3A/9V=3A，15V=2A/20V=1.5A
Strictly speaking, you can power two Raspberries from USB-A ports (marked IQ), and another one from the USB-C port (marked USB PD). This includes any external USB devices you attach to them. Since it's quite unlikely that all Raspberries ...
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I fixed the issue by having the computer that I was trying to ping the pi with plug into the router directly instead of having it plugged into a network switch that was plugged into the router.
As for the device being stuck in DORMANT mode, I fixed that using the following command: ip link set wlan0 mode default
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The answer is: it depends.
In general: before you move, make a backup. In that way you do not loose any data.
The rest depends a bit on how different the set-up will be in the new location and what the server actually does. If it is just an in-house server, and the IP plan is the same and the SSID/PSK are the same, it should just work. If anything changes,...
3
I'm curious what you might be encountering, because I have installed the latest versions of Raspbian on my oldest RPi devices and I haven't experienced any issues.
Supported Python Versions can be found here: Python Wiki
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The debug messages you are asking about are on a stage where only the boot loader is running but not even the kernel is loaded. So there is no chance to have logging to a file because there is nothing what managed it. But you can enable the boot loader to output messages to the serial debug console. For this you need an USB to TTL (RS232) serial cable. An ...
1
You have eth0 and wlan0 both connected to the same router and both connections are working as you can see if you ping its ip addresses. But the kernel can only use one connection at a time if you use a stateful tcp connection. This is the case with ssh. It starts a password enabled authenticated session on one connection to its destination ip address, e.g. ...
0
The traditional way to get into "Safe" mode, otherwise known as "single user" mode is to add an "S" to the end of the command line.
dwc_otg.lpm_enable=0 console=serial0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait S
Instead of bypassing all the system can do, this tells init the runlevel is "S", and it ...
1
My solution -- create a shell script to easily switch between AdHoc mode and internet connected mode
This does not configure OLSRd, it just creates an AdHoc network that you can connect to.
Shell script just copies the locally stored config files over to the location of the active config files
sudo cp /home/pi/adhoc_config/interfaces /etc/network/
sudo ...
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Because you started with a fresh flashed Raspbian Buster image so just enable WiFi as described at Wireless connectivity from the Raspberry Pi Foundation. If this doesn't work then you should have a look at the hardware of your RasPi or at the device from which you try to connect.
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It is known that the Raspberry Pi 3 may have problems with some devices to boot. But you can use a special bootcode.bin-only boot mode. This will use a SD Card containing only the file bootcode.bin. Once bootcode.bin is loaded from the SD card, the Pi continues booting using USB host mode. How to setup this you can look at Raspberry Pi boot modes.
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While not exactly an answer I have figured out the issue. After doing a lot more research i found that the twilio blueprint example i was following was using the OpenCV 2 as the basis for the functions. The only way now to proceed would be to rebuild the script with OpenCV 4 functionality.
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