Question

我试图通过Java点亮一个LED，但是当我运行我的项目时，我在输出中收到了这条消息：

wiringPiSetup: Unable to open /dev/mem: Permission denied
Unable to change ownership of /sys/class/gpio/gpio4/value: Operation not permitted
Unable to change ownership of /sys/class/gpio/gpio4/edge: Operation not permitted

如何获得使用GPIO引脚的访问权限？

程序：

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 HelloRPi 
{
    public static void main(String[] args) throws InterruptedException
    {
         System.out.println("Program started...");

        // create gpio controller
        final GpioController gpio = GpioFactory.getInstance();

        final GpioPinDigitalOutput pin = 
                gpio.provisionDigitalOutputPin(RaspiPin.GPIO_07, "REDLED", PinState.HIGH);

        System.out.println("--> GPIO state should be: ON");

        Thread.sleep(5000);

        // turn off gpio pin 
        pin.low();
        System.out.println("--> GPIO state should be: OFF");

        Thread.sleep(5000);

        pin.toggle();
        System.out.println("--> GPIO state should be: ON");

        Thread.sleep(5000);

        // toggle the current state of gpio pin  (should turn off)
        pin.toggle();
        System.out.println("--> GPIO state should be: OFF");

        Thread.sleep(5000);

        System.out.println("--> GPIO state should be: ON for only 1 second");
        pin.pulse(1000, true); // set second argument to 'true' use a blocking call

        gpio.shutdown();
    }      
}

设置（RPi B +）：（3V3）

Redwire：GPIO 7和30d
LED：（pos）30e和（neg）29e
电阻：29d和29b
GND：引脚9和29a

无法使用GPIO引脚进行输出

0 个答案: