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Questions tagged [pi4j]

Pi4J intended to provide a friendly object-oriented I/O API and implementation libraries for Java Programmers to access the full I/O capabilities of the Raspberry Pi platform. This project abstracts the low-level native integration and interrupt monitoring to enable Java programmers to focus on implementing their application business logic.

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javax.sql.DataSource-Spring boot

I'm a beginner and creating simple spring boot application with pi4j library, but i think have a problem with module-info.java. I don't know what's wrong. Is there a dependencies missing? I've tried different dependencies, changes in…
Dadzio008
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Raspberry Pi4 with Pi4j Java

I am trying to run a simple test on my Raspberry Pi4 using the pi4j java library v1.2. Somehow it's not doing anything. I also don't see any errors on console. It just finishes after 2 seconds. I'm expecting the LED light to turn on and turn off…
gtiwari333
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Struts2 and PI4J

I tryied to use a Struts2 web framework with PI4J to change relays status on Rapsberry 3B+ device on Tomcat 9 web container. My Action class. package com.action; import org.apache.log4j.Logger; import…
slaw77
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Pi4j Event Listener not triggered by GPIO status change

I have a simple Java program which should listen for changes of GPIO status. I'm using a button to change the status of a GPIO and from terminal I can see it works: Despite this, the event listener is never triggered. Here is the code: public…
CrystalSpider
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Controlling a servo at Raspberry Pi with Springboot and ServoBlaster

I am trying to control a servo motor from a web interface. I am using SpringBoot 2.0, ServoBlaster and pi4j. In order to start the application I am running as root ./gradlew bootrun --no-daemon. It has to be root in order to handle the GPIOs and I…
LiTTle
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Java: how to access a Class' methods which also handles gpio initializations, without creating multiple instances

In summary, my project is a JavaFX application which controls a stepper motor, controlled by the RaspberryPi using the Pi4j library. The first version of my program was a simpler Java implementation run through the terminal. In v1, I had 2 classes:…
StefKat
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Microsecond pulses with Raspberry Pi

Trying to output 10 mhz pulses with Raspberry Pi/pi4j, wiringPi... No problem with millisecond pulses This works on Mac...doesn't work on Raspberry Pi with pi4j and wiringpi installed: final long INTERVAL = 100; long start =…
sdvic
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Is there a way to define the pin with an input?

I'm trying to program a kind of dmx controller, therefore I got a RaspberryPi and now I want to write a program to controlle a GPIO with pi4j. The idea is to ask for the GPIO that should be the output, save it in a int and reuse this to tell pi4j…
Ramadorrn
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Pi4J : Detect all plugged devices

Is there a way to detect GPIO plugged devices using Pi4J ? Indeed, using GpioController object, you can get and change the state of the pin but not the presence/absence of device on it. I may use it mainly for relays and DS18B20 devices. If not…
Biologeek
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PWM on raspberry pi frequency always low

I wrote a program in java using the pi4j library, i tried setting the frequency divisor as low as possible as you can see, but i'm getting an output frequency of about 1Hz and i can't seem to get it any higher. Any thoughts? public class…
Simon Cools
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How can read more bytes via I2c

I'm looking for an example on how to read more then 1 byte on Raspberry Pi via I2C. I see only this, but works only for the first byte sent: package i2crpiarduino; import com.pi4j.io.i2c.I2CBus; import com.pi4j.io.i2c.I2CDevice; import…
Francesco Valla
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Pi4j compute GPIO Pin Status Raspberry

im trying to change a boolean value state with the corresponding state GPIO pin, but im doing this with not the attended result. public class PlayWithGPIO { public static boolean pinCarica = false; public static void main(String[] args)…
Francesco Valla
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DHT22 Sensor + pi4j + java

read temperature from DHT11, using pi4j I the tried the code in the following link with prerequisites : Java 1.8.0_65 pi4j 1.1 Raspberry Pi 3 Model B DHT22 Temperature sensor. Here when I am trying to execute the following both codes available in…
Arch
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schedule a pi4j / Java task using crontab

I want to run a Java / pi4j Task (Script ControlGpioExample) periodically using crontab on my Raspberry PI. This code works well on the Terminal: sudo java -classpath .:classes:/opt/pi4j/lib/'*' ControlGpioExample In Crontab I added the following…
tm011036
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Pi4j Anemometer - counter per interval

I'm trying to use a digital anemometer to work with my raspberry PI with pi4j. My idea was to add GpioPinListenerDigital to monitor when a pin goes high (means 1 complete anemometer rotation), but I cannot have it works... I would like to set an…
MarioC
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