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by rpdom
Sat Sep 05, 2020 4:50 am
Forum: Troubleshooting
Topic: Port forwarding using IFTTT
Replies: 29
Views: 804

Re: Port forwarding using IFTTT

Have you got the 1-wire interface enabled? That uses GPIO4/Pin 7.

You can disable it with "sudo raspi-config" under interfacing, or comment out/remove the "dtoverlay=w1-gpio" line in /boot/config.txt (which is what the raspi-config option does for you).
by rpdom
Fri Sep 04, 2020 9:23 pm
Forum: Off topic discussion
Topic: Android app development
Replies: 13
Views: 995

Re: Android app development

Apologies, I thought I posted this in the "off topic discussion" board. "Off Topic" here means "Does not fit any other category, but is still Raspberry Pi related in some way". since when, what are you talking about, where is this "rule" posted, have you nothing more productive to post about, are y...
by rpdom
Fri Sep 04, 2020 8:27 pm
Forum: Off topic discussion
Topic: Android app development
Replies: 13
Views: 995

Re: Android app development

carphone wrote:
Fri Sep 04, 2020 8:13 pm
Apologies, I thought I posted this in the "off topic discussion" board.
"Off Topic" here means "Does not fit any other category, but is still Raspberry Pi related in some way".
by rpdom
Thu Sep 03, 2020 6:16 pm
Forum: Beginners
Topic: Understanding the '&' and '>>' while running a file
Replies: 32
Views: 874

Re: Understanding the '&' and '>>' while running a file

GlowInTheDark wrote:
Thu Sep 03, 2020 12:21 pm
What is "logger"?
"logger" is a standard command to write messages to the syslog. man logger.
by rpdom
Thu Sep 03, 2020 11:48 am
Forum: Beginners
Topic: DS18B20 Waterproof sensor (how to connect via usb
Replies: 1
Views: 83

Re: DS18B20 Waterproof sensor (how to connect via usb

Well, that's not going to work. That's a USB to serial adaptor. The DS18B20 doesn't have a serial interface. It needs a 1-wire interface. I doubt you'll find a USB version of one of those. If could be possible with something like an Arduino to provide conversion between 1-wire and serial or even dir...
by rpdom
Thu Sep 03, 2020 7:08 am
Forum: General discussion
Topic: Mystery: some disks don't play on RPi while others do?
Replies: 11
Views: 520

Re: Mystery: some disks don't play on RPi while others do?

Region encoding on one disc and not the other?
by rpdom
Wed Sep 02, 2020 8:58 pm
Forum: General discussion
Topic: FM radio, any?
Replies: 4
Views: 177

Re: FM radio, any?

Yes, the WiFi/Bluetooth chip (not the SoC) has a radio receiver on it.

No, it can't be used as the pins for it are not connected.
by rpdom
Wed Sep 02, 2020 9:44 am
Forum: Beginners
Topic: Download URL data to stdout (BASH - sh)
Replies: 6
Views: 180

Re: Download URL data to stdout (BASH - sh)

Code: Select all

data="$(wget -O - "http://example.com/data?$(date +%s)")"
length=${#data}
if [ $length -gt 42 ]
then
  # Received data is long enough
  echo "$data"
else
  echo "Something missing? $data" >&2
fi
The "Something missing message" will be written to STDERR.
by rpdom
Wed Sep 02, 2020 9:33 am
Forum: HATs and other add-ons
Topic: Need some help with getting better temp readings with my Sense Hat ...
Replies: 8
Views: 306

Re: Need some help with getting better temp readings with my Sense Hat ...

just found it at the pihut now too, so look around https://thepihut.com/products/40-pin-gpio-male-to-female-ribbon-cable-150mm-gertboard https://cdn.shopify.com/s/files/1/0176/3274/products/IMG_2520_1000x.jpg P.S. I'm assuming you're UK based as you don't mention it. That's annoying that they've pu...
by rpdom
Wed Sep 02, 2020 8:49 am
Forum: Automation, sensing and robotics
Topic: Solenoid Valve receiving 12V DC but not opening or closing ?
Replies: 2
Views: 188

Re: Solenoid Valve receiving 12V DC but not opening or closing ?

The solenoid valve is probably trying to take more current than the opto-isolator can supply. The sustained maximum output current for a 4N25 is 50mA. How much does your solenoid need? You can probably get it to work by using the opto output to drive a more powerful transistor (possibly a mosfet, ju...
by rpdom
Wed Sep 02, 2020 8:43 am
Forum: Troubleshooting
Topic: php on vim E212 : Can't open file for writing
Replies: 2
Views: 91

Re: php on vim E212 : Can't open file for writing

You are trying to write the file into a location where your current user (pi?) doesn't have write permissions.

You can use "sudo vim" to give yourself root (administrator) permissions.
by rpdom
Wed Sep 02, 2020 8:28 am
Forum: General discussion
Topic: Repositories and Time Updates
Replies: 5
Views: 263

Re: Repositories and Time Updates

Time servers run (usually) on UDP port 123. I don't know why many admins block this mostly harmless port. I had a similar problem when using Pis at a Code Club in a local Library. I had to set the time manually in order to be able to get to the Code Club project website. Once you have the time set y...
by rpdom
Tue Sep 01, 2020 7:10 pm
Forum: Troubleshooting
Topic: RealVNC - Cannot Connect to Rpi From Mac OS
Replies: 4
Views: 113

Re: RealVNC - Cannot Connect to Rpi From Mac OS

Thanks for the input - didn't know that they could move a post between different forums! Yes, if you click the "!" icon or the one labelled "Report post" it has an option for "This post is in the wrong forum" and you can use the text box to say where you'd like it moved to. The mods are very happy ...
by rpdom
Tue Sep 01, 2020 7:02 pm
Forum: Beginners
Topic: Download URL data to stdout (BASH - sh)
Replies: 6
Views: 180

Re: Download URL data to stdout (BASH - sh)

How do I add time to the end of the URL instead of 123456? date +%s wget -q -O - 'http://example.com/data.txt?123456' > /dev/stdout sync sleep 5 Thanks to this, a new TXT file is always loaded. wget -q -O - "http://example.com/data?$(date +%s)" You don't need ">/dev/stdout" on the end as that is th...
by rpdom
Tue Sep 01, 2020 5:35 pm
Forum: Beginners
Topic: Download URL data to stdout (BASH - sh)
Replies: 6
Views: 180

Re: Download URL data to stdout (BASH - sh)

Code: Select all

wget -O - http://example.com
by rpdom
Tue Sep 01, 2020 5:33 pm
Forum: Troubleshooting
Topic: RealVNC - Cannot Connect to Rpi From Mac OS
Replies: 4
Views: 113

Re: RealVNC - Cannot Connect to Rpi From Mac OS

I posted this in the Beginner's Forum, but with no responses, I realized that it might be better in this forum, so here we go again: In future, please ask for the moderators to move your post to the correct area, otherwise they will get annoyed at reports of duplicate posts and people will get conf...
by rpdom
Tue Sep 01, 2020 4:04 pm
Forum: General discussion
Topic: Longevity of RPi USB ports?
Replies: 23
Views: 1010

Re: Longevity of RPi USB ports?

I find it strange that there isn't a chorus of 'that really needs to be improved'. The tin USB, and worse HDMI, are terrible on the Pi and in most portable devices I've seen. Pretty disgraceful for something that is supposed to travel and get set up in new places. If we're going to reserve them to ...
by rpdom
Tue Sep 01, 2020 11:55 am
Forum: Troubleshooting
Topic: systemd error messages that I don't understand.
Replies: 5
Views: 177

Re: systemd error messages that I don't understand.

Did you try the md5sum command I suggested to check that both files are identical?
rin67630 wrote:
Tue Sep 01, 2020 11:43 am
I never ever had to enter an absolute path for nc.
I don't even know how to specify it?
/bin/nc
by rpdom
Tue Sep 01, 2020 11:42 am
Forum: Beginners
Topic: Understanding the '&' and '>>' while running a file
Replies: 32
Views: 874

Re: Understanding the '&' and '>>' while running a file

OK now I understadn the differens and if I want to run 2 projects\files at the same time : test1 is printing time once every 1 sec test2 is printing cpu once every 1 sec put them in example.sh #!/bin/bash java -jar test1.jar >>output1.txt & java -jar test2.jar >>output2.txt & then I'm running from ...
by rpdom
Tue Sep 01, 2020 8:41 am
Forum: C/C++
Topic: wiringPi delay() in POSIX thread
Replies: 8
Views: 366

Re: wiringPi delay() in POSIX thread

but I still don't understand what this 2nd timespec is for in that case, and e.g., what to do then afterwards...? Well, if on exit that timespec contains something other than zero, you know you delay was cut short. You could decide to handle the reason for the interrupt, then nanosleep for the rema...
by rpdom
Tue Sep 01, 2020 8:35 am
Forum: Beginners
Topic: Camera options for raspberry
Replies: 8
Views: 335

Re: Camera options for raspberry

Hi, So if I understand correct, I cannot connect two raspberry pi camera modules at the same time? (at least those from your links?) Correct. The camera port on the standard Pi only supports one camera*. As mentioned, you can use USB cameras as well. *The Pi Compute Module has two camera ports, but...
by rpdom
Tue Sep 01, 2020 8:18 am
Forum: C/C++
Topic: wiringPi delay() in POSIX thread
Replies: 8
Views: 366

Re: wiringPi delay() in POSIX thread

just out of curiousity, why needs nanosleep 2 different timespec parameters? man nanosleep "If the call is interrupted by a signal handler, nanosleep() returns -1, sets errno to EINTR, and writes the remaining time into the structure pointed to by rem unless rem is NULL." Where "rem" is the second ...
by rpdom
Tue Sep 01, 2020 8:14 am
Forum: General discussion
Topic: Card game with raspberry and nfc
Replies: 1
Views: 121

Re: Card game with raspberry and nfc

There are cheap RFID (NFC) readers/writers which interface easily with the Pi. Look for RC522 devices. However, AFAIK they can only read/write one device at a time. You can't just put a stack of RFID-enabled cards on top of them and be able to read the values for all of them. The detection range is ...
by rpdom
Tue Sep 01, 2020 7:56 am
Forum: Troubleshooting
Topic: systemd error messages that I don't understand.
Replies: 5
Views: 177

Re: systemd error messages that I don't understand.

I suspect something went wrong with your Copy/Paste. Use the md5sum command to check that the two files are really identical. The meaning of this message in particular is obvious: Executable path is not absolute, ignoring: nc -u -l -p 4212 That would mean the ExecStart is ignored, so there is no val...
by rpdom
Mon Aug 31, 2020 6:20 pm
Forum: Ubuntu
Topic: Help with Config.txt file changes
Replies: 3
Views: 227

Re: Help with Config.txt file changes

My HDMI cable connection between my Pi4B and TV is missing audio support. What parameter in the config.txt file do I change so that Audio is handled through my HDMI cable connection? What value do I use to activate HDMI cable audio support? I want to avoid using a separate audio cable. Audio is sup...

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