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Questions tagged [real-time]

The actual time during which a process or event occurs: "information updated in real time". This topic covers how to control the Raspberry Pi in real time, how to use software in real time, and any other use of the Raspberry Pi in which real time control is needed. Not to be confused with real-time clock.

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124 views

Raspberry pi ntp client fails to sync on network master clock

I have a pi3B+ with stretch. I am trying to sync its clock using a network master clock (a pc set as ntp server) through direct ethernet connection. I can't see my server synching the pi. I followed ...
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0answers
17 views

PiCamera Minimal latency between real world event and digital data presence

Using a picamera, what is the best latency one can achieve from a real world event like an led lighting up and the Pi/MCU 'knowing' it has occured(by extracting image data)? I would also be ...
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0answers
20 views

Lagging/freezing

We are receiving signals from hardware components that we need to measure very precisely down to the millisecond. It is all working very well until a minor freeze occurs roughly about once every 3 to ...
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0answers
175 views

Access Timer Interrupts in Raspian

I want to write a C program that runs some code at a fixed interval (somewhere between 200us and 1ms, TBD). Is it possible to use the hardware timer interrupts to execute code without resorting to ...
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1answer
37 views

Display most recent image in folder on monitor

I currently have a receiver system that downlinks real-time images of earth from a weather satellite to a Raspberry Pi, where it then stores them as jpgs. What I am looking to do is automatically ...
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2answers
64 views

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 [closed]

import RPi.GPIO as GPIO import time GPIO.setwarnings(False) GPIO.setmode(GPIO.BOARD) GPIO.setup(3,GPIO.OUT) #Define pin 3 as an output pin while True: if(time.hour(18)&&time.hour(5)) #...
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0answers
28 views

Configuring Raspberry Pi Face Detection and Espeak

I am working with a Raspberry Pi Face Detection program and Espeak to tell that Human Face Detected. I'm using Pi Camera for face detection. The face detection program works fine. But the problem is ...
0
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1answer
97 views

How to know the buffer size of a Raspberry Pi 2 b?

I would like to know the size of my I/O buffer (defined as the queue where the packets arrive, e.g. from internet, and wait to be proccessed). How could I find this size? And if the buffer is too ...
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0answers
48 views

Is perfectly uninterrupted alsa sound over USB possible?

I am playing a sine wave from a Rpi3 via pure userspace ALSA to the hw device of a USB sound card (using the official PCM example, no sound servers installed). But the wave never stays perfect, after ...
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0answers
33 views

Script won't continue after command line

I am very new to Pi, Python, and this kind of programming, as a whole. I am building a data logger. Once completed, it will be deployed in areas with no internet connectivity. So I chose to create ...
2
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1answer
55 views

Execution interruption while holding a kernel spin lock

I want to toggle an GPIO pin with a certain accuracy. (i.e. latency about 1 us). I have a Raspberry Pi 3 model. Therefore I wrote a simple test kernel module. The toggling loop does basically this: ...
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0answers
172 views

Raspberry Pi3 should I use multi-threading, interrupts or callbacks?

Project Description I am interfacing industrial PLC's with the Raspberry Pi 3 in order to read the efficiency of the given line, and display live results. In essence I need to do the following things:...
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0answers
82 views

Display Real-time processed images in Raspberry Pi

I am working on real time image processing in raspberry Pi. Goal is to fetch and process 64x64 frame with 60 fps. I am using numpy to process these frames. And i want to display these processed images ...
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2answers
291 views

How to synchronize images from two raspberry pis

I have 2 Pi Zero Ws (wifi), each with a Pi camera connected to them. Both Pis/cams are running on battery power and deployed in the desert. There is no network or internet connection. The cams are ...
2
votes
1answer
697 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 ...
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2answers
2k views

Continuesly monitor GPIO input change/events in Bash

On a Raspberry Pi you can set the GPIO pins as an output or an input. An output or an input can be either high or low. For example, to monitor the input state (high or low) of GPIO pin 26 you can ...
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1answer
468 views

is rpi suitable for hard real time ECG signal processing? [closed]

I am working on moniroting system for medicacl care and I can't deside what to use , having that the processing includes denoising , segmentation feature extraction and machine learning another ...
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1answer
1k views

Trying to apply real time patch to kernel 4.9.76

Raspberry Pi 3 model B OS: Raspbian 9.3 stretch Kernel: armv7l Linux 4.9.76-v7+ CPU: ARMv7 rev 4 (v7l) @ 1.2GHz RAM: 1GB I'm trying to apply the real-time patch (it's highly desirable for my ...
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2answers
129 views

CPU speed changes by a multiply of 2 for short durations

I'm using a raspberry pi and I need really fast performance from my CPU for a certain process. To achieve that, I added isolcpus=3 to my kernel boot parameters, to isolate the core for this process ...
2
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0answers
175 views

Using Hardware pwm as event timer?

in modern PC based Linux Machines it is possible to use hpet and realtime processes to get a reasonable good realtime performance (+-10us response time) While Raspberry Pi Hardware does not have a ...
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0answers
2k views

How to achieve better Jitter for LinuxCNC on Raspberry PI?

Question Is it possible to achieve reasonable real-time with RaspberryPi (ideally jitter < 50us, or in the worse case 150us ) If yes, how to achieve those values, targeting LinuxCNC? After all ...
2
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1answer
3k views

Saving graphs using Matplotlib is very slow

I am trying to write a python Code snippet which creates 24 figures and 9 subplot and saves them in the directory. Its taking around 197 sec to create all the 24 figures and save them. This is ...
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1answer
404 views

Fastest wired data transfer protocol between RPi and Android Device

I'm looking to download images that i'm capturing on RPi to my Android Device using USB, or some wired interface that I don't know about. I'm trying to avoid using wifi, ethernet, or bluetooth. I've ...
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0answers
845 views

raspi+ADC realtime plotting

I recently succeeded in receiving ADC Data from ADS7851 through SPI communication. Now I'm working on plotting those voltage data and also fft of them. I've done some research, and found out that ...
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1answer
1k views

code to read live mic input audio frequency

My project is to create a kit to play recorded (music chords) audio file automatically changed with respect to frequency of live microphone input with a certain period.This will help the solo singers ...
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0answers
107 views

Setting maximum process pause time - need to read spi data with less time gaps

I am using a raspberry pi to grab data through a SPI port. Attached to the SPI port is a PIC, programmed so that it samples on an A/D at 12.8kHz, and stores the samples in a 256 long buffer. (to cope ...
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1answer
448 views

Stable Linux kernel version with RTPreempt Patch for Raspberry Pi3 ModelB

I am installing a real time preempt kernel for my Raspberry Pi3 ModelB. I installed the linux kernel version 4.4.50 and I patched this kernel with RT_Preempt patch-4.4.50-rt63. However, every time I ...
2
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1answer
5k views

Perform a task upon a voice command

I would like to do on-board speech processing (Matching of a pre-recorded voice sample [1/2 secs] with a continuously playing sound) with a Pi 3. The Pi should give a real-time response to the ...
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2answers
3k views

PyAudio recording from multiple microphones

I am trying to detect peaks from two microphones at the same time with python and pyaudio and calculate the time difference between them. I'm using two Konig usb microphones (http://www....
7
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1answer
2k views

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

On the Arduino / ATmega328p, the 16-bit Timer/PWM modules have a input capture unit that allows the precise time of arrival for an input edge to be recorded even if the processor is busy when the ...
0
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1answer
626 views

Raspberry Pi Kernel Compilation Problem

I am trying to cross compile a raspberry Pi kernel with RT Preempt patch. I am following this tutorial. I have downloaded the latest kernel sources rpi-4.9.13 and the corresponding rt patch patch-4.9....
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2answers
1k views

What real-time operating systems are supported by the Raspberry pi 3 model B?

I have been looking around for multiple RTOS for the rpi3 but unfurtunately many of them are not (yet?) supported? Could anybody tell me which ones can be used on the rpi3 now?
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1answer
6k views

How to disable or shutdown NTP daemon?

I am running PI 3 as a standalone system. Therefore, it won't have internet connection and pi's date and time is manually set and Real Time Clock chip is used to keep the pi's date/time current. It ...
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2answers
89 views

Handling sensor data and reacting on ms timescales

I have two related questions. I'm happy to get advice or links to recommended reading as well. How many times per second can a Pi pull data over SPI Over SPI what sort of timescale can I query ...
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2answers
250 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
120 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 ...
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1answer
1k views

Increase webcam fps = Raspberry Pi processing speed increase?

I'm using a Raspberry Pi B+ board for color processing in real time and the current processing speed is extremely slow. While I don't need to show the processed image to a display, the speed of ...
2
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0answers
391 views

Camera OV5647 + 3.5 LCD as a real time view

I have a OV5647 camera and 3.5 GPIO LCD. I would like to connect both of them to have a real time view in my Raspberry Pi 3. I would like to also set by programming to turn on the camera after some ...
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1answer
4k views

Possible to display current time in pi camera recording?

Well I guess the title sums it up pretty good. I know I can do annotations but they're just strings which can't be altered or am I wrong? Is it possible to always have the time in the video recording? ...
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1answer
873 views

Real time adc for RPI

I'm thinking about a project with RPI. I need 4 or 6 analog inputs with sample rate between 500 and 1000 samples per second and 2 or 4 digital output as response of processing the input signals. ...
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1answer
60 views

Why crontab choose to execute one of the command over other?

So, basically I am using wiringPI library and its sample code for ds1302 chip. It works great by the way - writing and reading to and from ds1302 chip is a breeze. I can initiate PI's date and time ...
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1answer
199 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....
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1answer
293 views

2D - 3D video conversion in Raspberry pi

We have a system that we can not change. Systems output is 2D video in DisplayPort format. Video is in 1080 p resolution and 120 Hz. We need to convert this 2D video to 3D in realtime. We will be able ...
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4answers
32k views

Does the Raspberry Pi 3 support RTOS?

I am new to the RTOS world. I am planning to use some RTOS on a Raspberry Pi 3 (may be FreeRTOS). Can anyone suggest which RTOS would be good for the beginners? Since they have not released a ...
0
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1answer
97 views

Update time again with terminal or Bash after bootup

I use my Pi as part of a home automation system, logging and carrying out events according to time. It is connected to a working internet connection, but let's say the power temporarily goes out and ...
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1answer
2k views

Using GPU to decode QRCODE

I'm using a raspberry pi compute module and my question is : Can we use the GPU to decode QRCODE ? I am using my own function inspired by the one from QRTOOLS and by doing so the timing is divided by ...
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2answers
1k views

RT patch is freezing

I have patched PREEMPT-RT for Raspbian Linux kernel. It works fine for normal operations (web browsing or short time programs) the following is the output of uname -a of my Rapsberry Pi 2 after ...
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2answers
396 views

Triggering two USB cameras connected with single Pi at the same time

Is it possible to trigger two Cameras connected by USB to a single RPi at the same time with 1 ms latency?
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0answers
144 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 ...
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0answers
34 views

How to make servos not jitter without extra hardware [duplicate]

To control a servo, I'm using this. To summarize it: you use code like this: while True: GPIO.output(pin, GPIO.HIGH) time.sleep(0.0015) GPIO.output(pin, GPIO.LOW) time.sleep(0.0185) ...