Questions tagged [timekeeping]

Use this tag for any question related to keeping accurate time. Note there is a more specific "NTP" tag for questions related to that.

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1
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3answers
69 views

Reading time off of a cellular modem with python 2.7 and pyserial

TL;DR: I need to read the time off of my Hologram Nova USB cellular modem on /dev/ttyACM0 and update the system clock after the pi restarts. I'd like to do it in Python but it isn't reading the ...
-2
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1answer
17 views

For the Chrony refclock directive, how is the precision option used?

The man page says the precision of the reference clock has units of seconds. What do those seconds measure?
0
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1answer
67 views

Raspberry pi 2 model b system clock ppm

I have a Raspberry Pi 2 model B and a RTC (precision 1 ppm) hooked up with, without Internet conneciton. When the RPi is power off is the RTC the responsible to keep the current hour but when the RPi ...
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2answers
322 views

Count time between two pulses in nano seconds

How can i count time between two pulses in nano seconds by using raspberry pi?
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1answer
561 views

Sync time for all Raspberry Pi's on local network without internet

There are 5 Raspberry Pi's connected to one switch (No Internet) using LAN cables. One of the Raspberry Pi has RTC module connected and it has correct date and time. Now how can all remaining four RPi'...
5
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2answers
681 views

Setting up time on Raspberry Pi with Ubuntu LTS 18.04

It seems I am unable to set up permanent time on my Raspberry Pi 3 with Ubuntu LTS. I tried: sudo timedatectl set-ntp 0 sudo timedatectl set-time "2018-09-17 18:17:16" sudo timedatectl set-timezone ...
0
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1answer
192 views

Read-only system with hwclock, but I need to change the datetime

I created a read-only system from this adafruit link (https://learn.adafruit.com/read-only-raspberry-pi/ ). I have a hwclock and want to change the datetime regularly. But calling hwclock --set --...
1
vote
1answer
77 views

Getting changes in the timezone on a raspberry pi reflected in PHP

I am using the lighttpd webserver on a pi running raspbian stretch, with php version 7.0. I can get a string representing the current date, time and timezone information onto a web page by calling ...
2
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1answer
879 views

HIgh resolution timer?

Is any high resolution timer available on a Raspberry Pi that can be used by an application (for micro-benchmarking, etc.) without having to write a kernel driver? The resolution I'm looking for is ...
1
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1answer
38 views

Syncronize a datetime beetween Raspberry and a SmartPhone

I have an offline webserver on my raspberry pi. How would I be able to get the date from a device to my raspberry pi?
0
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1answer
48 views

Will linking the clock file to an in-memory file lower the wear on the SD card?

I use systemd-timesyncd, which writes a status (probably) to a file at every synchronization. As the Arch documentation mentions, The service writes to a local file /var/lib/systemd/clock with ...
2
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1answer
82 views

Odd results when measuring timing

Some introduction to my case: I have an ADC (MCP3008) connected to my RasPi with SPI. To that ADC I have connected 2 multiplexers (4051 dip-chips, I plan on connecting 8 multiplexers eventually). So ...
3
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2answers
10k views

Set manually datetime raspberry

I have a project that uses Raspberry in offline mode. We know it doesn't have a clock when it powers off. The router, even in offline mode, have a clock when it power off. So, i have 2 questions: 1 -...
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5answers
1k views

Switch out the X1 Oscillator on a RPI 2/3

Just like a lot of people I'm using a RPi as a NTP server (more info about the basic setup here: https://framkant.org/2017/03/stratum-1-ntp-server-with-freebsd-on-raspberry-pi/) I have found that the ...
1
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2answers
76 views

start videoplayback simultaneously on 5+ PIs

I am helping friend of mine with her exhibition in video arts. Right now her concept requires 6 Beamers to loop videos, distributed over three floors in an relatively large building, with one PI per ...
2
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0answers
89 views

How to manually adjust system clock for testing purposes

I have written a Python script that is set to run different functions at different days/times. I would like to test it by setting the system clock to 1-2 minutes before the dates/times that the Python ...
2
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1answer
1k views

How to implement Precision Time Protocol (PTP) on Rpi3 p2p network?

I was just wondering whether IEEE 1588 PTP can be implemented on RPi-3 network? Like any other linux system whether ptp4l and phc2sys are functional in raspbian? Any idea, link or suggestion? Any ...
1
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2answers
306 views

RTC drifts when rebooting

I'm working on a project where an RTC (DS3231) is needed since the RPi will not have continuous access to the internet. I've been able to set the clock on time and keep it but I've observed that a ...
0
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1answer
1k views

Read and store timestamp value from hwclock (RTC)

Background: I successfully configured a DS3231 RTC to keep time and I can correctly read it with hwclock -r or hwclock -D commands. Question: How do I store timestamp value (e.g. 1500075260) into a ...
8
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2answers
7k views

How do I set Raspbian to use the primary time server time.nist.gov?

I have several Rpi3s running Raspbian. They collect data and I use FileZilla to copy data from one to another. Ideally, I am only copying files that have changes or are new. FileZilla can be ...
0
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1answer
434 views

Alarm clock triggering RasPi IoT functions?

I am quite new to the RasPi community, but I got drawn here by a very specific use-case: I wanted to build my own (configurable) alarm clock connected to further devices in my home. A first step ...
1
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2answers
2k views

ntpd -gq hangs and time is not updated

In attempts to synchronize time, following the advice to run $ sudo ntpd -qg. This does not terminate on its own, and the time is not updated. How to debug this problem? pi@raspberrypi:~ $ sudo /etc/...
12
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3answers
39k views

Time and timezone issues on Pi

I've a raspberry Pi that I was using in EST timezone. It had ntp service installed (sudo apt-get install ntp) and the Pi was set to UTC timezone. The date on the Pi was correct, until I took the Pi to ...
1
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2answers
266 views

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

I am running Pi 3 along with Real-Time Clock chip ds1302 and using wiringPI library to read and set date and time to and from ds1302 chip. After I set my Pi's system date and time to local date and ...
2
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1answer
132 views

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

I have two Pi 3 running at the same time with my program being executed while both are plugged into a power source with current date and time and not connected to the Internet. Couple of days later I ...
5
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2answers
16k views

LibreELEC: Fix date

Using LibreELEC v7.0.2 with Kodi 16.1 on a Raspberry Pi 3. The date and time is incorrect. It can temporarily be fixed by SSH'ing and running date --set with a provided date. But on boot, the date ...
0
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1answer
174 views

ngnix logging datetime doesn't match system time

date command prints correct datetime according to my timezone. but ngnix logging with different datetime. this makes me wonder if there are independent multiple source for datetime in unix? how can ...
2
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1answer
629 views

Can I tell if NTP Synch has happened since boot?

I'm using a Raspberry Pi 2 (Jessie) to log some data. It only runs for a few hours at a time. When I boot it, the clock is wrong. This has been discussed at length in a number of threads. I'd like to ...
1
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1answer
2k views

Does Raspberry PI work with UTC time by default?

I have a program that runs on Raspberry PI that is completely depended on localtime. Otherwise, it will completely FAIL. On a Linux system like Magiea, it doesn't have any issues running as it should. ...
1
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1answer
203 views

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

Finally, I am able to write to and read from DS1302 chip through Raspberry PI 2 Model B, but now I noticed that time is not accurate for my timezone. In fact, it is offset by 4 hours in 24 hour format....
1
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4answers
591 views

Where exactly are these GPIO pins located on Raspberry PI 2 Model B?

I am having hard time understanding the Raspberry PI 2 Model B's PINOUT. I have RTC Module I want to use with my PI, but no matter what I do there seems to be NO response at all from RTC. I even ...
11
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7answers
69k views

Raspberry Pi won't update time

I bought a Raspberry Pi 3 approximately two months ago, and since then time has never updated. Details: The operating system is a fresh installation of Raspbian Jessie (4.1.19-v7+). The Internet ...
0
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1answer
849 views

HC-SR04 ultrasonic sensor reading becomes highly unusable when PWM is active

Good day I am trying to sample distance using a sonar/ultrasonic sensor for altitude measurement. When the PWM is not active, the sensor gives accurate measurements in centimeters, however with the ...
1
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0answers
148 views

Raspberry pi execution time calculated is different on the desktop terminal and command line?

Boot to desktop and boot to command line can be chosen using raspi-config. I decided to do a test to see whether my code will execute faster using the command line interface. How come the raspberry ...
3
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3answers
2k views

Raspberry Pi Time is off by 45 min

I'm currently running a Pi as a file and Webserver on my small home network. My two Windows-10 PCs have the correct time, but I noticed the Pi time is approx 45 minutes off. No big deal, but when I ...
4
votes
2answers
648 views

Log correct boot time

I have a Raspberry Pi 2 Model B that I use as a mini server and I'd like to get an accurate reading of the times the system is switched on. The problem is not the shutdown times, which are logged ...
3
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2answers
884 views

Make sntp run on boot in Jessie

I am building a raspbian-based distro (FullPageOS), and it seems like on boot of the latest Jessie sntp service is running, internet connection is established, but sntp is not updating the clock to ...
4
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3answers
749 views

How to display real time on a Pi

How do I give my Pi system a Real Time Clock (RTC)? Is this possible? As each time when I power off my Pi, and the next time when it boots, it displays the previous power off time. Can someone ...
2
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1answer
3k views

Cannot ping localhost

While setting up an ntp client/server, I found a weird error where the client cannot check it's own time. I have traced this back to the fact that all of these commands time out: ping localhost ping ...
0
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1answer
603 views

Automatically synchronise time with mac on local network without internet access

I want my RPi to have the same time as my mac that I use to command it using SSH. The RPi and mac are connected on a local network without internet access. Currently each time the RPi restarts or ...
1
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4answers
148 views

why two RPis show quite different ntp results?

I have two RPis running on the same network, with the same Internet access. One of them is a B and the other one a B+ model. Both run the same distro with ntp enabled for quite a long time (this is to ...
5
votes
3answers
913 views

How can I get a clock in C accurate enough to control a servo?

I want to write a program that controls a servo motor myself using a pi B+. Controlling the motor involves sending 1.5 millisecond pulses along a GPIO pin every 20 milliseconds. I have tested the ...
0
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2answers
394 views

Installing Tracks 2.2.3 on Raspberry Pi

I want to install Tracks on my Raspberry Pi for task/time management. My Pi is running the latest Raspbian, i.e. I have updated it to the latest package versions. There is a rather cryptic guide on ...
3
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2answers
1k views

ntpq -p reports all available servers have stratum 16

ntpq -p reports all available servers have stratum 16. Therefor the time is cannot be set. However I can ping all the servers. ntpq -p remote refid st t when poll reach delay ...
0
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2answers
241 views

Smallest interval that RPi can record

I was planning to determine light speed by myself(which is 3*10^8 m/s). I have kept 2 sensors, and I need to know the time interval as light strikes the sensors. It lies somewhere about 50nanoseconds. ...
0
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1answer
1k views

Chrony 506 Cannot talk to daemon

I'm having trouble configuring chrony to sync the time between my raspberry pi and a desktop computer in an isolated network. My raspberry pi's chrony.config file looks like this: server master ...
5
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2answers
1k views

Make RPi keep an semi-accurate time after power loss

I use Motion detection and a webcam as a security camera. It's headless with no internet or keyboard. To turn the camera off while it's not need I just turn the power supply off. Because I shut it ...
8
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4answers
18k views

After reboot, my RPi is one hour off — How to adjust for Daylight Savings problems?

The electricity to my apartment went out a few days ago. I use my RPi to record data and store it in a database. I've just learned that the time for all my data has been off by an hour because the ...
8
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3answers
4k views

How does Pi keep track of time interval?

As I understand RTC is needed to keep track of time. However, Raspberry Pi does not have that and use NTP servers to synchronize its time. All that is fine, but how does Pi know that one millisecond ...
44
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6answers
152k views

Where does the Raspberry Pi get the time from?

I don't have to set the clock (besides the timezone) on the Raspberry Pi. Where is it getting the time from? About how accurate is it?