Questions tagged [signal]

Use this tag for any question involving types of communications . Generally at the hardware level such as electric voltage levels or light colors. Modulation is a key component of data signaling, but the mere presence of a voltage can signal availability of a device.

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51 views

How to use 2 GPIO pins for 3 buttons

I am using almost all the GPIO pins on a project so I had to be resourceful when adressing the pins for the buttons. But I just can’t get it to work. I don't know if something is wrong with the code ...
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28 views

What is going on with the Raspberry PI SPI? Weird jitter in signal

I'm using python and spidev to do spi transactions over the Raspberry Pi's spi channel. I'm having a couple of different things happen that are not what I am expecting. This is a capture of a spi ...
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23 views

Calculating a time-varying voltage output that simulates a modulated carrier wave

So I have this measurement instrument and I want to transmit its data (database files from MySQL) at low frequencies (80-100kHz) through a limestone cave ceiling to the surface. Disregarding the ...
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34 views

Button event stops working after signal.pause

I've coded a simple reaction time game, where an LED lights for a random time, after which the first of two buttons to be pressed is the winner. I have a working example using threading.Event: from ...
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1answer
149 views

Raspberry pi4 + ADC

I have been working with Raspberry pi 4 to acquire analog signals. I get AD/DA High Precision Board by Waveshare (ADS1256 A/D) to convert analog input and I downloaded python source code from ...
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1answer
333 views

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

I need to acquire a signal at a minimum sample rate of 10 kHz and processing it real-time using a Python code. Since Raspberry Pi only reads digital signals I get an ADC (High Precision AD/DA Board ...
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1answer
63 views

Sending a NEC like signal via a GPIO

I'm trying to control an existing LED strip controller with a Raspberry Pi. The controller has an IR receiver to receive commands. I removed the IR receiver of the controller and added a connection to ...
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1answer
107 views

Waveshare AD/DA espansione board setting sampling frequency

In order to acquire 3 analog signals with Raspberry pi 4 I want to use ADS1256 Waveshare's AD expansion board ( 8 channels single-ended, 24 bit). I was wandering if there's a way to set a different ...
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2answers
87 views

GPIO 3.3 V signal still readable after inputting high resistance values

I recently obtained a raspberry pi 4 (8GB) and I am trying to understand the GPIO behavior and ran into an event that I don't understand. I have set-up a simple script that allows pin 36 (GPIO 16) to ...
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2answers
189 views

Monitor only recognises the signal when started first

My monitor, an old Toshiba 47wlg66, will display what my boards output (whether it's my old raspberry pi 1 A or new raspberry pi 4 B) only if it was powered first. Otherwise it will remain black.. It ...
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34 views

How can I control pins with node js + gpiozero + signal?

I have a project written in python using the gpiozero library controlling some buttons, an LCD, and some LEDs. The file follows the format of setting callback functions, defining event handlers, and ...
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1answer
949 views

Connecting Raspberry Pi 4 to old VGA monitor

I'm trying to set up an old monitor to use with my Raspberry Pi with Ubuntu 20.04, but whatever options I try, my monitor doesn't detect any signal coming from raspberry. I have original HDMI cable ...
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66 views

High-precision time-varying PWM outputs on R Pi

I'e seen a lot of examples of simple PWM on the Pi where relatively high-precision PWM signals at a fixed duty cycle can be generated using WiringPi or pigpio in hardware PWM mode. I have tried ...
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24 views

Monitor not recognized by other devices after having connected my raspberry pi 4

I have a weird problem and I simply can't find any solution to it: I use a Fujitsu Siemens monitor with a dvi to hdmi cable which works just fine with all my devices. However, after I connected my ...
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1answer
104 views

PedalPi, lag when piping in data

I am modifying a pedal pi (link here). I split the input program from the output program. For simplicity right now, that all it does. The standard out from my input program is being fed to the ...
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509 views

Interpreting voltage output on ADC with rated AC current sensor

I know I have asked similar questions before, but I have switched sensors and encountered interesting results that I do not understand. Purpose: I intend to use an AC current sensor to measure ...
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0answers
40 views

HDMI No signal on one tv but signal fine on another

I am using a pi zero w. I have used it on two TV's to date. It's been a month or so since I last used it and now it works on only one of the TV's. This wouldn't be a problem but I am giving this to ...
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1answer
246 views

Interpreting 10-bit ADC output

I am having difficulty understanding the output from my ADC. I am using a 10-bit MCP3008 with a photoresistor and CT current sensor connected into the analog inputs. I am reading the signals with this ...
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1answer
107 views

How to enable sending keyboard signals while in SSH?

When I use a keyboard plugged into the pi directly, I can send signals using ctrl+T / ^T to get messages from ongoing commands in terminal. When I'm logged in via SSH on my mac, I seem to lose this ...
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2answers
1k views

Broadcast VHF or UHF to CRT TV

I picked up this TV and thought it may be fun to use it with a Raspberry Pi. https://www.cnet.com/products/spectra-52-bw-5-crt-tv/ However, I soon realized the only way to get a video signal to the ...
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2answers
723 views

How can Rpi read ADS1256's negative values?

I'm using this Raspberry Pi High-Precision AD/DA Expansion Board from waveshare. I have some questions regarding its ADC (model name: ADS1256) unable to give out negative value. Specifically, only ...
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2answers
403 views

Raspbian Stretch lite doesnt send HDMI signal on second boot

I have installed the most recent Raspbian Stretch lite (release: 2018-11-13) to a SanDisk ultra A1 micro SD card to use it for my Raspberry Pi model 3B. I connected a HDMI monitor and a USB keyboard ...
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1answer
115 views

Generating signals with Pi

I have a vector of 500 numbers and would like to output these at a sample rate of 1kHz, thus a signal time of 0.5seconds. Is there any way to do this using a Pi? Do the GPIO pins only allow for an On/...
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855 views

Python script wait for button press before starting/stopping a separate python script

I've written a python script (shown below) which starts and stops another separate python script (datalogger) once a button is pressed. The datalogger script records logic levels (0 or 1) and stores ...
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1answer
7k views

How to start and stop python script using button

I've written some python code that should start and stop another python script (Datalogger) when a button is pressed. So when the Pi is booted up I'm wanting the button script to run and then once I ...
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0answers
97 views

Data acquisition using DSO 2150 (Hantek, Virtins, etc.) in Raspberry Pi

I have Virtins 2815H which is a DSO based on DSO 2150, I would like to real time record a signal around 1 MHz using it and process it in Raspberry Pi. I have searched a lot about the data comm from ...
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3answers
1k views

GPIO relay signal cross turns to all relays staying on after Darlington added

I have 4 Sunfounder 2 channel relays 7 of which that I'm using to control some things on my aquarium. I suspect that I may have wired them up wrong somehow though. The behavior I'm seeing is as ...
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2answers
2k views

GPIO.wait_for_edge and signal.signal()

I have the below sample code that is trying to implement a safe shutdown mechanism ( yet to fully implement) For some reason, I am not able to catch any signals using the registered signal handlers. ...
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0answers
27 views

Changing RPi version may lead to binary corruption?

Apologizes for the object, but I cannot easily summarize the scenario. I created an sd-card based upon Raspbian Stretch Lite, with some customization. Then I cross-compiled Qt5.9 and copied the ...
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1answer
836 views

SignalR on Mono Raspbian

Had tried to launch SignalR client (.NET Framework 4.5 target) on my Pi 3 with Mono on Raspbian. But it's not working because SignalR's throws a System.InvalidProgramException - something wrong with ...
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1answer
689 views

Send and receive 868Mhz signals with my Pi

My home lighting is achieved using wireless Delta Dore switches working in 868 Mhz. Here are my switches reference : https://www.deltadore.fr/data/product_files/6351091/documents/notices/Util/fr/...
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0answers
244 views

Raspberry Pi + Windows 10 IoT Core + RS485

Has somebody ever worked with windows 10 IoT Core and used RS485? I would like to receive some signals from the RS485 device. I would like to do this with Windows universal app.
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2answers
11k views

Raspberry Pi no signal to hdmi

This is the first time I've tried to use a raspberry pi, I bought a CannaKit that came preloaded with NOOBS. When I attempt to boot with the HDMI my screen says no signal, the HDMI output is correct, ...
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1answer
8k views

Control signal strength of Raspberry Pi 3 WiFi signal down to minimum

With the Raspberry Pi (latest Raspbian OS) configured as a WiFi Access Point that gives internet access through ethernet interface, I'm doing some WiFi Signal Strength testing. In reduced space to ...
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1answer
1k views

Square wave generator using RPi 2

I am completely new to this and I am not into programming. My requirement is to generate a 965Hz precise square wave. This frequency may need fine tweeking from 955Hz to 975Hz depending on other ...
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1answer
341 views

Minimum TTL 5.0V signal duration

I'm working on a little project in my physics lab. We would like to create a photon coincidence counter. We were thinking to use the Pi GPIO pin to monitor a couple of photo diode which produce a 15ns ...
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3answers
835 views

Can I use the Ethernet (RJ45) port on the RPi to place telephone calls?

I would like to use an RPi as an analog landline, and was wondering if instead of having to use a serial port to connect a modem that generates DTMF, if the Ethernet port could be used to generate ...
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2answers
693 views

How to find distance and direction of IR signal?

I am wondering where I should start in trying to get my Raspberry Pi to detect the distance of an IR signal and the direction of it. Has someone already done something similar? The end goal is to get ...
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1answer
1k views

Listen to 433MHz signals in the background

How can I listen for 433MHz signals in the backgrounds from boot on? I am using this receiver / transmitter pair here. An Arduino sends signals to the Raspberry Pi and I want to listen for them in ...
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1answer
932 views

How to show audio signal on the screen of raspberry pi? and how to input the sound signal? [closed]

The screen i used is http://www.amazon.co.uk/Touch-Screen-Designed-Raspberry-Model/dp/B00UV78E9Q/ref=sr_1_14?ie=UTF8&qid=1432902157&sr=8-14&keywords=raspberry+pi+2 I would like to know how ...
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1answer
119 views

IOError exception not handled within signal handler

I am usig a RPi as a datalogger for an accelerometer, the ADXL345 breakout from Sparkfun. Since I need the accelerometer to sample at an exact frequency of 200Hz, I am using a signal to trigger the ...
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1answer
1k views

Problems triggering via GPIO

I am building a network of Raspberry Pis, and want a lot of Raspberrys to take a picture after receiving a Trigger Signal. I want to send this Trigger Signal via a GPIO Pin. It sounds simple, and I ...
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1answer
2k views

Import composite/ntsc-signal

I already googled a lot and mostly read that importing composite Signal to the Raspberry is almost impossible. I would just take a webcam and proceed since it seems to be a lot easier. The problem is,...
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1answer
185 views

Real-Time Computaion! Processing Speed Problem!

I am pretty new to the c++ and raspberry pi. I am trying to run a real time sensor motor control with the help of Raspberry pi, using cpp. I am sniffing the sensor data through Ethernet and sending ...
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2answers
2k views

How to generate a PWM signal with Visual Basic? [closed]

Please help me to get PWM signal (three LEDs) from raspberry pi by using Visual Basic. I have a problem to generate pulse signal from raspberry pi wirelessly. What I want to do is using a program to ...
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1answer
2k views

Pin current protection circuit

I want to use one of the Raspberry Pi's GPIO pins as a shutdown signal to an Arduino. The idea is, that when the Raspberry starts up, it holds this pin high and when it completely shuts down, it ...
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2answers
1k views

What is a accurate way to generate and decode IR signals?

I want to receive and generate IR signals with my PI. What is the best way to reliably do this? Would it be with something like this?
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4answers
27k views

How can I generate frequency / pulse signals?

I am looking at ways to use the Raspberry Pi as a signal generator. Currently I am working on hooking up an inexpensive AD9850 module from ebay. This will generate fairly accurate frequencies up to ...