12 votes
Accepted

How to disable or shutdown NTP daemon?

I believe you're looking for systemctl disable systemd-timesyncd.service I wouldn't worry about syslog trashing your SD card (it would take years if not decades), but disabling a service you don't ...
Dmitry Grigoryev's user avatar
7 votes

How to precisely capture the arrival time of an input edge?

For a general Linux solution pigpio is probably the best you are going to find. It uses DMA to capture the GPIO levels and uses DMA to time-stamp the event time from the 1MHz system clock. The ...
joan's user avatar
  • 70.9k
7 votes

Does the Raspberry Pi 3 support RTOS?

Although the original project only supports Raspberry Pi 1, I have succesfully compiled this fork on a Raspberry Pi 2, and it says to support 3 also. https://github.com/Forty-Tw0/RaspberryPi-FreeRTOS
jordi's user avatar
  • 183
5 votes
Accepted

Using GPU to decode QRCODE

In theory, you could use the OpenGL API to speed things up a bit. There's no implementation of OpenCL for now. You could design your code such that its calculations are a fragment shader according to ...
Aloha's user avatar
  • 7,126
5 votes

Does the Raspberry Pi 3 support RTOS?

Until now I tested the following RTOS without success for raspberry pi 3, that will help someone to not lose time (I wast 3 month) : FreeRTOS, Xenomai, RTEMS, BitThunder, ChibiOS/RT For RISC OS it is ...
Mahmoud Almostafa RABBAH's user avatar
5 votes

How to synchronize images from two raspberry pis

You've said, "I'm not an expert with Linux systems or the Raspberry Pi, so please thoroughly explain your solution." Fair enough, but if by a "thorough explanation" you expect to avoid any further ...
Seamus's user avatar
  • 21.8k
4 votes
Accepted

How do you force wiringPI library to use local time instead of UTC time?

The use of UTC time seems to be hardcoded in ds1302 utility. Note the following line: gmtime_r (&now, &t) ; This converts your system time to UTC, before writing it to the DS1302 chip. When ...
Dmitry Grigoryev's user avatar
4 votes

Does the Raspberry Pi 3 support RTOS?

ARM, the ISA family used by the Broadcom processors on all current Raspberry Pi models, is based on RISC, for which RISC OS is written. RISC OS I think predominated on ARM devices for their first ...
goldilocks's user avatar
  • 58.7k
3 votes

Perform a task upon a voice command

You are going to need an internet connection, an OS, (I suggest Raspbian) and a microphone. The first step is to get the microphone set-up. Start by opening a terminal window and running lusb. This ...
Darth Vader's user avatar
  • 4,206
3 votes

Setup microphone stream and turn your raspberry pi into a baby phone

I think you should try one of two things. Firstly if you want low latency, you should ditch the USB approach which has more latency then one of these GPIO header based sound cards. This can take you ...
Matt's user avatar
  • 966
3 votes

RT patch is freezing

If somebody finds this via search engines: Re-compiling anything won't help at all, don't waste your time on that. It's simply an issue with the Kernel and/or the Raspberry Pi firmware. See here: ...
Pavel Pipovic's user avatar
3 votes

How to use ntp time as default time while using Raspberry Pi as a gateway?

Recent Raspberry Pi OS includes systemd-timesyncd as the NTP client. Unfortunately for you, systemd-timesyncd does not implement the server functionality, so it cannot provide network time to clients ...
Dmitry Grigoryev's user avatar
3 votes

Real time + High frequency ADC data reading with Raspberry Pi 4

Linux is not a real-time operating system. You will not be able to achieve consistent sampling times using the standard Linux environment. I have used DMA bit banging to get accurately timed SPI ...
joan's user avatar
  • 70.9k
3 votes

RPI 0w: automatic timezone syncronization

From Terminal call setuo by command: sudo raspi-config Select Internationalization Option to set Time Zone Time and date are automatically set from network if you connected to the internet. If you are ...
user16181's user avatar
3 votes
Accepted

RPI 0w: automatic timezone syncronization

I used solution from here with my small changes: zone=$(wget -O - -q http://geoip.ubuntu.com/lookup | sed -n -e 's/.*<TimeZone>\(.*\)<\/TimeZone>.*/\1/ p') if [ "$zone" != "...
Rougher's user avatar
  • 99
3 votes

Raspberry Pi network time, and accurate time for astronomy Data taking needs, at a loss

You can run systemd-timesyncd as @Milliways has documented or you can switch back to the old ntpd. Support for this was dropped by Raspbian/RaspiOS a few years ago. To switch first you need to disable ...
Dougie's user avatar
  • 5,271
2 votes

Is it possible to run real time software?

Since 2018, the Pi kernel comes with a set of -rt branches on github: this is what I'd try first if I wanted to test a realtime kernel on the Pi. Currently the patched kernel version is 4.19. Clicking ...
Dmitry Grigoryev's user avatar
2 votes
Accepted

Why is DS1302 chip time be offset by 4 hours even though the system time is accurate for the Time Zone?

The norm for GNU/Linux systems is to set the hardware clock to UTC (I'd guess this is most likely true for POSIX systems generally) aka. "universal common time" or "coordinated universal time", ...
goldilocks's user avatar
  • 58.7k
2 votes

What would cause pi's system date and time to drift while plugged into a power source and not on the Internet?

If you shutdown the Pi, then restart it restores the time to that last saved, which it does periodically while running. The "culprit" is fake-hwclock, although this is better than the default, which ...
Milliways's user avatar
  • 59.6k
2 votes

Increase webcam fps = Raspberry Pi processing speed increase?

Admittedly the CPU on the RPI B+ isnt the greatest (single core, 700MHz w/o overclocking), but there is a chance there might be other issues slowing down your processing pipeline Have you done any ...
Shreyas Murali's user avatar
2 votes
Accepted

Possible to display current time in pi camera recording?

The picamera documentation page includes a basic recipe for a timestamp overlay, which I've just tested, which puts a second-accurate timestamp (yyyy-MM-dd HH:mm:ss) at the top of the video. import ...
goobering's user avatar
  • 10.7k
2 votes

Saving graphs using Matplotlib is very slow

You could try to use matplotlib without QT, i.e. with a non-interactive backend, if non-interactive plotting generating image files only is the goal. It will skip any overhead related to the GUI ...
Ghanima's user avatar
  • 15.8k
2 votes
Accepted

PyAudio recording from multiple microphones

I finally managed to calculate the time difference of arrival with the usb microphones and to actually calculate a coordinate and show this on a map (created with matplotlib). I just connected the ...
bilal0302's user avatar
2 votes

CPU speed changes by a multiply of 2 for short durations

I don't know what is happening but don't forget that you still share resources with the other cores. It can well be that another core is causing replacement of your core code in the L2 cache. Maybe ...
Oldfart's user avatar
  • 188
2 votes

CPU speed changes by a multiply of 2 for short durations

Interesting question - something is competing for CPU resources. have you looked at cpu temperature - is it throttling due to heat? pi@marvin:~$ sudo vcgencmd measure_temp temp=47.1'C from ...
DTick's user avatar
  • 81
2 votes

HIgh resolution timer?

You should be able to check for high-resolution timer support by installing the rt-tests package and running cyclictest with the period that you're interested in. For example cyclictest -n -p 80 -i ...
Dmitry Grigoryev's user avatar
2 votes

Execution interruption while holding a kernel spin lock

Even though you are using Linux you might be better off asking at the raspberrypi.org baremetal forum. They are probably more aware of potential glitches. I know of two potential glitch sources. ...
joan's user avatar
  • 70.9k
2 votes

Why is my code not working between time hours?And what should be done if im using PIR sensor ,what is the change that should be done in this code

This line: if(time.hour(18)&&time.hour(5)) #The function turns on between 6pm and 5am is wrong in two ways. First, there is no function time.hour(n). To get the current hour in local time, ...
sweber's user avatar
  • 516
2 votes
Accepted

Is it possible to have a Raspberry Pi work like a much faster arduino

That is very much the premise of Ultibo. What is Ultibo? Imagine if you could have the simplicity and freedom of Arduino with the power and features of a Raspberry Pi. With the ease of a ...
joan's user avatar
  • 70.9k
2 votes

RPI 0w: automatic timezone syncronization

The timezone is the area in which the device is located. The problem is that something must know what timezone your client is in. If you don't know it, how should the client know it? It could connect ...
Ingo's user avatar
  • 42k

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