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PORaspberry pi flashing LED issue - Python vs Java
 

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  1. PORaspberry pi flashing LED issue - Python vs Java
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    <p>i am trying to make an LED light flash on the raspberry pi using some code i found online ( i know - not the best but it was a tutorial site)</p> <p>When i run the following python code the led light flashes;</p> <pre><code>import RPi.GPIO as GPIO import time pinNum = 4 GPIO.setmode(GPIO.BCM) #numbering scheme that corresponds to breakout board and pin layout GPIO.setup(pinNum,GPIO.OUT) #replace pinNum with whatever pin you used, this sets up that pin as an output #set LED to flash forever while True: GPIO.output(pinNum,GPIO.HIGH) time.sleep(0.5) GPIO.output(pinNum,GPIO.LOW) time.sleep(0.5) </code></pre> <p>When i run the following Java code which is supposed to do the same - all i get to the console are the print statements which i have added - no flashing light</p> <pre><code>import com.pi4j.io.gpio.GpioController; import com.pi4j.io.gpio.GpioFactory; import com.pi4j.io.gpio.GpioPinDigitalOutput; import com.pi4j.io.gpio.PinState; import com.pi4j.io.gpio.RaspiPin; public class ControlGpioExample { public static void main(String[] args) throws InterruptedException { final GpioController gpio = GpioFactory.getInstance(); final GpioPinDigitalOutput ledPin = gpio.provisionDigitalOutputPin(RaspiPin .GPIO_04, "MyLED", PinState.LOW); System.out.println("Started"); try { while(true) { System.out.println(ledPin==null); System.out.println("Looping pin now"); ledPin.high(); System.out.println("Set high called"); Thread.sleep(2000); ledPin.low(); System.out.println("Set low called"); Thread.sleep(2000); } } catch(Exception ex) { gpio.shutdown(); ex.printStackTrace(); } } } </code></pre> <p>Does anyone know why this might be? I think logically the should be doing the same thing - both are using the same GPIO pin number from the pi too</p> <p>Thanks for your help</p>
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    1. COAre you sure both pins map to the same 'physical' pin? The diagram under the 'pin numbering' header here http://pi4j.com/usage.html seems to have them enumerated differently than the design specification. Given that the operations succeed I'd consider it likely that you're not using the correct pin index.
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