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by jojopi
Tue Apr 03, 2018 2:29 pm
Forum: Troubleshooting
Topic: Symbolic linked directories and ".." - why though?
Replies: 1
Views: 156

Re: Symbolic linked directories and ".." - why though?

This is a special feature of the shell's "cd" command. It keeps track of the path names used to get to your current directory, and by default it implements ".." by taking off the last component, instead of following the real ".." file on disk. You can also use "cd -P .." to go to the physical parent...
by jojopi
Mon Mar 26, 2018 6:28 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Accessing permission to open port /dev/ttyS0 for Serial communication
Replies: 6
Views: 3780

Re: Accessing permission to open port /dev/ttyS0 for Serial communication

[email protected]:~ $ sudo chmod 777 /dev/ttyAMA0 ACTION=="add", KERNEL=="ttyS0", MODE="0666" Let us not go crazy. 0666 or 0777 is never the right mode for anything. The problem here is that something else is using the device. That is why it is in group "tty" instead of "dialout". Disable serial shell in th...
by jojopi
Tue Mar 06, 2018 5:15 am
Forum: Troubleshooting
Topic: No logging output of python script at @reboot
Replies: 7
Views: 641

Re: No logging output of python script at @reboot

Standard output is buffered by default. Terminal output is buffered by lines, but output to files is buffered in blocks. This program prints five characters every five seconds, so it will take well over two hours before there is 8KiB in the buffer and Python passes the data to the OS. However, when ...
by jojopi
Tue Feb 27, 2018 2:47 pm
Forum: Camera board
Topic: libjpeg62 wants to remove packages
Replies: 1
Views: 249

Re: libjpeg62 wants to remove packages

libjpeg62 was superseded by libjpeg62-turbo, which is almost certainly already installed. However, for building applications you may need the development package: sudo apt install libjpeg62-turbo-dev You do appear to have found a bug with the repositories. In Debian stretch, attempting to install li...
by jojopi
Wed Feb 14, 2018 4:22 pm
Forum: Off topic discussion
Topic: It *has* to happen!
Replies: 28
Views: 3357

Re: It *has* to happen!

And also a 5 in 6 chance of it not being the same, a 16777215 in 16777216 chance of not being the same for a pi. So if P = 16777215/16777216 then having two Pi's the probability of not being the same is P, three Pi's P*P, for four P*P*P etc, P^(N-1) With each additional selection there is one fewer...
by jojopi
Mon Feb 05, 2018 6:01 am
Forum: Raspberry Pi Desktop for PC and Mac
Topic: Files Are Compiled As Shared Libraries Instead Of Executables
Replies: 18
Views: 1803

Re: Files Are Compiled As Shared Libraries Instead Of Executables

The behavior is occurring because newer ubuntu distros set GCC default link flag -pie, which marks e_type as ET_DYN on the binary file. Consequently, the Operating System recognizes as Shared Library. You have not explained how this matters. Yes the compiler makes position independent executables b...
by jojopi
Tue Jan 23, 2018 2:24 pm
Forum: Troubleshooting
Topic: Directory listing Vulnerability at http://downloads.raspberrypi.org/weather_station/images/
Replies: 5
Views: 530

Re: Directory listing Vulnerability at http://downloads.raspberrypi.org/weather_station/images/

Whether that is a vulnerability or not really depends on how one views it. AFAICT no files are being exposed other than what were intended to be exposed. I do not see how it should ever be regarded as a vulnerability. If the files are supposed to be accessible to the public then there is no problem...
by jojopi
Mon Jan 22, 2018 1:31 pm
Forum: Beginners
Topic: Converting incoming messages to Unicode.
Replies: 5
Views: 606

Re: Converting incoming messages to Unicode.

I am not familiar with NRF24, but the results from printDetails() do seem wrong. For instance you asked for AutoAck, but EN_AA is zero. And the values for RF_SETUP and DYNPD appear to have reserved bits set. Do the printed rate and power values even change if you try to set them up differently? My g...
by jojopi
Thu Jan 18, 2018 2:53 pm
Forum: Advanced users
Topic: the key g (0x0a) does not work for USB HID gadget
Replies: 2
Views: 410

Re: the key g (0x0a) does not work for USB HID gadget

Why are you using bash? My guess is that the combination of shell redirection and echo -ne is causing the output to be line-buffered. \x0a is also the newline character \n, so the rest of the string is another line. Kernel device drivers and other pseudo files expect to get your complete request as ...
by jojopi
Thu Jan 18, 2018 11:59 am
Forum: Beginners
Topic: Internal pull up/down function explanation
Replies: 16
Views: 4519

Re: Internal pull up/down function explanation

You can measure the effect of the internal pulls on an output. If you drive a GPIO low but also load it to 3.3V with 330Ω, that gives about 300mV at the pin. Now you should see at least 1mV difference between each of the internal pull up, no pull, and pull down states. The level registers always rea...
by jojopi
Wed Jan 17, 2018 12:33 pm
Forum: Troubleshooting
Topic: Removing Kernel Warning
Replies: 12
Views: 1139

Re: Removing Kernel Warning

That message is considered an error, not a warning, and you asked for loglevel=3. You can decrease that further if you do not even want errors to go to console: loglevel= All Kernel Messages with a loglevel smaller than the console loglevel will be printed to the console. It can also be changed with...
by jojopi
Wed Jan 17, 2018 11:19 am
Forum: Beginners
Topic: Internal pull up/down function explanation
Replies: 16
Views: 4519

Re: Internal pull up/down function explanation

You cannot use internal pulls on an output. You can configure internal pulls regardless of whether the pads are set as input, output, or alternate function. The pulls stay in circuit even when they are competing with the output drivers, though obviously they make next to no difference in that case....
by jojopi
Mon Jan 15, 2018 4:34 pm
Forum: Troubleshooting
Topic: Can't view man pages
Replies: 3
Views: 332

Re: Can't view man pages

teytur wrote:
Mon Jan 15, 2018 2:23 pm
/home/pi/bin/man: 1: /home/pi/bin/man: Syntax error: ")" unexpected]
You have created a file /home/pi/bin/man (apparently full of erroneous syntax), and it is taking precedence over the system utility /usr/bin/man.
by jojopi
Mon Jan 15, 2018 8:08 am
Forum: Raspberry Pi Desktop for PC and Mac
Topic: Think I’ve nailed the Raspi Boot Loop bug
Replies: 13
Views: 999

Re: Think I’ve nailed the Raspi Boot Loop bug

I am not sure that Fake_News even has a Pi. His previous thread about boot issues was regarding the Foundation's x86-32 live image.

Branding seems to be really important these days. You cannot just explain a problem; it has to be "Raspi Boot Loop" or "Shellshock".
by jojopi
Mon Jan 15, 2018 7:54 am
Forum: Beginners
Topic: In which order does a Python Program run
Replies: 18
Views: 1376

Re: In which order does a Python Program run

You need to identify the entry point. In C and C++ it's some variation of Main(), in Python and Basic it's whatever you come to after initial imports, declarations and definitions. In Python, the entry point is always the top of the file! Even "from module import just_one_thing" executes the whole ...
by jojopi
Sun Jan 14, 2018 12:03 pm
Forum: Beginners
Topic: In which order does a Python Program run
Replies: 18
Views: 1376

Re: In which order does a Python Program run

I found the initial query about order of execution confusing because, in almost any language, the answer is that the program runs from the top to the bottom. Except obviously as modified by flow control statements, procedure and function calls, imports, exceptions, threads, etc. However, the mention...
by jojopi
Sat Jan 13, 2018 1:03 pm
Forum: General discussion
Topic: When will Raspberry Foundation admit that the Pi destroys your SD cards?
Replies: 88
Views: 7548

Re: When will Raspberry Foundation admit that the Pi destroys your SD cards?

To those who claim to run 24/7 without issues: I'm pretty sure your use-cases are not really write-heavy, am I right? If you acknowledge that the problems result from heavy writing, then I do not see how it could be the Raspberry Pi "boards" that are at fault, as opposed to the software you were ru...
by jojopi
Sat Jan 13, 2018 1:35 am
Forum: Python
Topic: Attribute error in python 3
Replies: 4
Views: 805

Re: Attribute error in python 3

Where did you get the code from? After the "class MrBit_QTR_8RC:" line, each of the next ten "def method (self…):" lines should have been indented four characters so that they belong to the class. (The bodies of those definitions are already indented eight characters to make room.) Because your defi...
by jojopi
Wed Jan 03, 2018 8:37 pm
Forum: General discussion
Topic: Chip architecture - is the Pi vulnerable?
Replies: 46
Views: 5422

Re: Chip architecture - is the Pi vulnerable?

Paul Webster wrote:
Wed Jan 03, 2018 5:51 pm
probably should have been
"they are are not likely to have implemented the same bug"
I suspect the second "are" was a substitute for the "not"/"un-", rather than there being both an extra word and a missing one.
by jojopi
Wed Jan 03, 2018 12:56 pm
Forum: Troubleshooting
Topic: When are Predictable Network Interface Names Assigned? - Stretch
Replies: 19
Views: 6169

Re: When are Predictable Network Interface Names Assigned? - Stretch

The idea is that when I plug a USB-ethernet adapter into a Pi it gets an interface name derived from it's MAC address? That has been disabled by default. You are months too late to join the ranting about it. What would be useful would be if the interface name (or serial port name) was derived from ...
by jojopi
Wed Jan 03, 2018 4:22 am
Forum: Troubleshooting
Topic: GKSU cannot open display
Replies: 2
Views: 478

Re: GKSU cannot open display

The title mentions GKSu, but the transcript shows plain sudo.

Did you try "gksudo gparted" ?
by jojopi
Tue Jan 02, 2018 11:25 am
Forum: General discussion
Topic: OTB Bit Has Not Been Programmed - but it has! ???
Replies: 9
Views: 975

Re: OTB Bit Has Not Been Programmed - but it has! ???

I think the error message is telling you that the OTP bit cannot be programmed -- because it already has been! The bit is programmed by the GPU firmware early in the boot sequence. Where would such an error appear? The documented method for checking the bit is "vcgencmd otp_dump |grep 17:". This si...
by jojopi
Sun Dec 31, 2017 11:35 pm
Forum: Advanced users
Topic: Maximum current and voltage through the 40 pins before damage?
Replies: 11
Views: 1413

Re: Maximum current and voltage through the 40 pins before damage?

GPIO's configured as outputs, but outputting a '0' don't either, […] Only if they actually source a current into a load they do. So we can sink 16mA into each of the 28 GPIOs driven low, for a total of 0.458A? No, I suspect there will be similar limits for sinking and sourcing. It may be slightly b...
by jojopi
Sun Dec 31, 2017 1:02 pm
Forum: General discussion
Topic: Syntax error on import time
Replies: 17
Views: 2413

Re: Syntax error on import time

2. Idle – Run Config – have created new folder Test_Sen and changed name of file Test_Two.py, but the test still goes to RPi.py as before, is there a preferred method of creating new directory? This does seem to be another Idle quirk. Normally a local file will override a system module only if it i...
by jojopi
Sat Dec 30, 2017 9:40 pm
Forum: Troubleshooting
Topic: Password
Replies: 12
Views: 1021

Re: Password

You can try to launch a (second) GUI using:

Code: Select all

startx -- :1
Presumably this will fail. (If you could launch a session you should be able to log in using the existing GUI, and anyway autologin would be working on boot.)

Maybe the error messages will help point to the problem.

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