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by pfletch101
Sat Jun 15, 2019 8:39 pm
Forum: General discussion
Topic: Forgot my password.
Replies: 11
Views: 455

Re: Forgot my password.

I have so many files though. I'd suggest you get in the habit of backing up work you want to save. I do it daily. I copy the tar files to my Windows PC that's also backed up daily. Even better, set up Cron jobs to do this at times when your Pi is usually running. I have a series of Cron jobs backin...
by pfletch101
Sat Jun 15, 2019 8:29 pm
Forum: General discussion
Topic: Problem with WIFI on latest full raspbian
Replies: 9
Views: 359

Re: Problem with WIFI on latest full raspbian

JFYI You can use the downloaded file as is with no need to unzip it first. Win32Disk Imager and Etcher can write to the SD card with it as is. Are you sure Win32DiskImager can use the zipped file? Yes, I verified it myself by downloading a new stock zip file. You have to tell it to look for all fil...
by pfletch101
Mon Jun 10, 2019 7:25 pm
Forum: Troubleshooting
Topic: Corrupt files within /var/lib/dpkg/info, and 'error processing package udev'
Replies: 2
Views: 93

Re: Corrupt files within /var/lib/dpkg/info, and 'error processing package udev'

I would guess that either your SD card has been corrupted by powering off without shutting down or it has reached its 'sell by date'. I would burn Raspbian to a new card and try that.
by pfletch101
Mon Jun 10, 2019 1:18 am
Forum: Raspbian
Topic: The much heralded "Buster"- When? [now!]
Replies: 26
Views: 1897

Re: The much heralded "Buster"- When?

https://wiki.debian.org/DebianBuster Are you agreeing or disagreeing with jamesh? Your linked page states explicitly that Buster is "the current testing distribution" (my emphasis). The RPF folks are, indeed, testing it. In due course, after the stable version is available, they will release a vers...
by pfletch101
Mon Jun 10, 2019 12:56 am
Forum: General discussion
Topic: Packages installing in wrong folder in Raspberry pi 3
Replies: 5
Views: 232

Re: Packages installing in wrong folder in Raspberry pi 3

I always thought you had to CD into the installation directory before downloading and installing? (or move the file to the target directory before installing) If you use pip, pip3, or apt (or apt-get, which is almost a synonym for apt), your files will be installed in the location which the utility...
by pfletch101
Fri Jun 07, 2019 9:58 pm
Forum: Raspbian
Topic: Is Rasbpian legal in the USA?
Replies: 16
Views: 759

Re: Is Rasbpian legal in the USA?

klricks wrote:
Fri Jun 07, 2019 9:55 pm
No...
I think/hope that you are answering the OP's second question, rather than the one in his 'Subject'!!!
by pfletch101
Fri Jun 07, 2019 8:50 pm
Forum: Python
Topic: Running multiple while true loops
Replies: 5
Views: 229

Re: Running multiple while true loops

Just to increase complexity: modern concepts are asynchronous. See https://docs.python.org/3/library/asyncio.html A quick scan did not tell me what asyncio was doing 'under the hood', but it is presumably either using threads or subprocesses (or both) and providing a 'wrapper' round them. As I note...
by pfletch101
Fri Jun 07, 2019 3:36 pm
Forum: Python
Topic: Running multiple while true loops
Replies: 5
Views: 229

Re: Running multiple while true loops

More complex answer: Use threads. One while loop per thread. Hit the python docs and your preferred search engine for more info on threads in python. Slightly more complex answer, still: use multiprocessing. The problem with threads in Python is that a single process can only have one thread active...
by pfletch101
Mon Jun 03, 2019 6:53 pm
Forum: General discussion
Topic: Switch for different power sources?
Replies: 6
Views: 207

Re: Switch for different power sources?

Hi! Thank you very much for your answers! That's very kind of you! In my scenario the Raspi doesn't have to run without interruption. That should make it easier. I want to be able to switch and switch it on afterwards. In some ways, it makes it slightly more difficult, since you need to provide for...
by pfletch101
Sun Jun 02, 2019 9:51 pm
Forum: General discussion
Topic: Switch for different power sources?
Replies: 6
Views: 207

Re: Switch for different power sources?

This will be difficult if the 'power supply' is feeding directly into the Pi, since only a small, very transient voltage drop can be tolerated at the Pi's power feed. If I wanted to do this - e.g. to have a Pi running primarily on solar power but with mains or a battery as a secondary power source, ...
by pfletch101
Sat Jun 01, 2019 9:00 pm
Forum: Raspbian
Topic: Access the hwrng.bin file (random number generation)
Replies: 5
Views: 256

Re: Access the hwrng.bin file (random number generation)

Thank you so much! It did cost me so much time but its finally starting to work out haha! So simple but you have to know .. This treats the binary file or the output of the urandom device as a byte stream (which is basically what it is - actually a bit stream). I think that the OP may be looking fo...
by pfletch101
Sat Jun 01, 2019 5:26 pm
Forum: Python
Topic: Trying to make a speedometer using hall effect sensor and a neodym magnet
Replies: 7
Views: 222

Re: Trying to make a speedometer using hall effect sensor and a neodym magnet

I am not asking if you can guarrantee that 10KHz would be enough at hight speeds... but do you THINK it would work.. or do I need better resolution? There are two aspects of frequency response that you need to think about. One is the number of activations a second that the sensor can deal with. Tha...
by pfletch101
Fri May 31, 2019 3:10 pm
Forum: Raspbian
Topic: Access the hwrng.bin file (random number generation)
Replies: 5
Views: 256

Re: Access the hwrng.bin file (random number generation)

You can convert binary files to hex numbers using hexdump. This 'cat's the urandom devices through hexdump to make it human readable. cat /dev/urandom | hexdump Or in your case hexdump hwrng-data.bin This treats the binary file or the output of the urandom device as a byte stream (which is basicall...
by pfletch101
Thu May 30, 2019 3:38 pm
Forum: Beginners
Topic: Fish Tank Temperature Monitor - Pi Zero - Thermistor
Replies: 17
Views: 640

Re: Fish Tank Temperature Monitor - Pi Zero - Thermistor

The fundamental problem you are facing is that the Pi has no analog inputs. So, somewhere between the thermistor and the Pi you need an A/D converter. ….or you can use the workaround that can be found in a number of temperature sensor projects - determine the time that it takes to charge or dischar...
by pfletch101
Wed May 29, 2019 8:58 pm
Forum: Troubleshooting
Topic: Apt-get update running very slow?
Replies: 8
Views: 990

Re: Apt-get update running very slow?

DougieLawson wrote:
Wed May 29, 2019 12:46 pm
That is 100% normal when the raspberrypi-kernel package gets an update.
Text about diversions is usual under those circumstances, but I've never seen an update take anything like half an hour.
by pfletch101
Sun May 26, 2019 7:02 pm
Forum: Raspbian
Topic: Can't Compile Any More! Please need help!
Replies: 10
Views: 758

Re: Can't Compile Any More! Please need help!

There is an even better way to upgrade: - freeze the environment on your current system, that means no more updates - buy a new raspberry and a new memory card - install a new copy of stretch - install and configure whatever you need - transfer anything you need from the current system to the new s...
by pfletch101
Sun May 26, 2019 6:58 pm
Forum: Raspbian
Topic: Can't Compile Any More! Please need help!
Replies: 10
Views: 758

Re: Can't Compile Any More! Please need help!

Upgrading (in place) a system to Stretch is an iffy process. When I tried it, last year, I encountered all sorts of issues. The usual recommendation is to burn the latest version of Stretch to a new SD card and then reconfigure it to your taste. The time that this takes is (for most people) well wo...
by pfletch101
Sat May 25, 2019 2:54 pm
Forum: Raspbian
Topic: Can't Compile Any More! Please need help!
Replies: 10
Views: 758

Re: Can't Compile Any More! Please need help!

Upgrading (in place) a system to Stretch is an iffy process. When I tried it, last year, I encountered all sorts of issues. The usual recommendation is to burn the latest version of Stretch to a new SD card and then reconfigure it to your taste. The time that this takes is (for most people) well wo...
by pfletch101
Thu May 23, 2019 3:42 pm
Forum: General discussion
Topic: Static IP Address
Replies: 2
Views: 156

Re: Static IP Address

In my opinion (and that of a number of others who have weighed in on this question in the past), the preferred way of doing this is by setting up your router to assign this IP address to your Pi, based on its MAC address. You can determine the latter by typing (for a wired connection): ifconfig eth0...
by pfletch101
Mon May 20, 2019 7:25 pm
Forum: Automation, sensing and robotics
Topic: DS18B20: Influence of supply voltage on temperature
Replies: 15
Views: 702

Re: DS18B20: Influence of supply voltage on temperature

that the almost certainly increased 'wasted' current flow with increased supply voltage through the circuitry around the sensor was heating it up, so that it was correctly reading a higher temperature. I still don't think so. These sensors have been around for decades, long before Raspberry Pis exi...
by pfletch101
Sat May 18, 2019 7:12 pm
Forum: Automation, sensing and robotics
Topic: DS18B20: Influence of supply voltage on temperature
Replies: 15
Views: 702

Re: DS18B20: Influence of supply voltage on temperature

But to answer your question, I am not sure why the change in Vdd to the sensor would change the temperature reading. Could it be something as simple as heating due to increased power dissipation in the sensor at the higher supply voltage? Scrubbing the data sheet for the sensor, there is nothing to...
by pfletch101
Thu May 16, 2019 7:25 pm
Forum: General discussion
Topic: my service is not starting at power up [solved]
Replies: 16
Views: 399

Re: my service is not starting at power up

You should modify your script so it does not die if the service it depends on is not available. How can I do that? In one important sense, you can't! If the service it depends on doesn't start up at all and/or fails after starting up normally, your script presumably cannot start or carry on. What y...
by pfletch101
Thu May 16, 2019 2:04 pm
Forum: General discussion
Topic: my service is not starting at power up [solved]
Replies: 16
Views: 399

Re: my service is not starting at power up

I'm running a Blynk script using Python in this matter: phone app <-> server <-> script. Threfore, if the local server (installed on the same board where my code is running) is not up and running before the script's execution, the service call fails. That's to be expected as it makes sense. I just ...
by pfletch101
Wed May 15, 2019 10:14 pm
Forum: General discussion
Topic: my service is not starting at power up [solved]
Replies: 16
Views: 399

Re: my service is not starting at power up [SOLVED]

No, no graphics involved. Python code is trying to connectet to a local (127.0.0.1) server. it appears that the below line helped delaying the script thus solving my issue. ExecStartPre=/bin/sleep 30 Thank you. That (or an equivalent) was going to be my next suggestion. It doesn't really fix the un...
by pfletch101
Wed May 15, 2019 10:00 pm
Forum: General discussion
Topic: my service is not starting at power up [solved]
Replies: 16
Views: 399

Re: my service is not starting at power up

As Paeryn implies, the script must be assuming something about its environment that is true in a running system but not true when the system is in the process of booting up. The usual culprit is networking, but this does not seem to be the case here. If the script does do something with graphics, it...

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