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@L4grange L4grange/GPIO.java forked from rosterloh/gpio.java
Last active Nov 24, 2018

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Android class for GPIO control
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
/**
This class allows you to control GPIO pins form android, by abstracting the command line excecution into a java class.
IMPORTANT NOTE: Requires root to run, since it is required to write to GPIO ports in /sys/class/gpio/
*/
public class GPIO {
static String TAG = GPIO.class.getSimpleName();
public static String DIRECTION_IN = "in";
public static String DIRECTION_OUT = "out";
public static int VALUE_ON = 1;
public static int VALUE_OFF = 0;
private String port;
private int pin;
//Constructors
public GPIO(int pin) {
this.port = "gpio" + pin;
this.pin = pin;
}
public GPIO(int pin, String direction) {
this.port = "gpio" + pin;
this.pin = pin;
initPin(direction);
}
/// Export GPIO pin
private boolean activatePin() {
String command = String.format("echo %d > /sys/class/gpio/export", this.pin);
try {
Runtime.getRuntime().exec(new String[]{"su", "-c", command});
return true;
} catch (IOException e) {
log.e(TAG, "Failed to export " + port, e);
return false;
}
}
/// Unexport GPIO pin
public boolean deactivatePin() {
String command = String.format("echo %d > /sys/class/gpio/unexport", this.pin);
try {
Runtime.getRuntime().exec(new String[]{"su", "-c", command});
return true;
} catch (IOException e) {
log.e(TAG, "Failed to unexport " + port, e);
return false;
}
}
/// Initialise the GPIO pin
public int initPin(String direction) {
int retour = 0;
boolean ret = true;
// see if gpio is already set
retour = getValue();
if (retour == -1) {
// unexport the gpio
ret = deactivatePin();
if (!ret) {
retour = -1;
}
//export the gpio
ret = activatePin();
if (!ret) {
retour = -2;
}
}
// check if gpio direction is defined
String ret2 = getDirection();
if (!ret2.contains(direction)) {
// set the direction (in or out)
ret = setDirection(direction);
if (!ret) {
retour = -3;
}
}
return retour;
}
/// Get direction of GPIO
public String getDirection() {
String command = String.format("cat /sys/class/gpio/%s/direction", this.port);
try {
Process p = Runtime.getRuntime().exec(new String[]{"su", "-c", command});
BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
StringBuilder text = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
text.append(line);
text.append("\n");
}
String retour = text.toString();
return retour;
} catch (IOException e) {
log.e(TAG, "Failed to get direction of " + port, e);
return "";
}
}
/// Get state of GPIO for input and output and test if it is configurate
public int getValue() {
String command = String.format("cat /sys/class/gpio/%s/value", this.port);
try {
Process p = Runtime.getRuntime().exec(new String[]{"su", "-c", command});
BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
StringBuilder text = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
text.append(line);
text.append("\n");
}
try {
String retour = text.toString();
if (retour.equals("")) {
return -1;
} else {
return Integer.parseInt(retour.substring(0, 1));
}
} catch (NumberFormatException nfe) {
return -1;
}
} catch (IOException e) {
log.e(TAG, "Failed to get value of " + port, e);
return -1;
}
}
/// Set the value of the GPIO output
public boolean setValue(int value) {
String command = String.format("echo %d > /sys/class/gpio/%s/value", value, this.port);
try {
String[] test = new String[]{"su", "-c", command};
Runtime.getRuntime().exec(test);
return true;
} catch (IOException e) {
log.e(TAG, "Failed to set value of " + port, e);
return false;
}
}
/// Set the direction of the GPIO pin
public boolean setDirection(String direction) {
String command = String.format("echo %s > /sys/class/gpio/%s/direction", direction, this.port);
try {
Runtime.getRuntime().exec(new String[]{"su", "-c", command});
return true;
} catch (IOException e) {
log.e(TAG, "Failed to set direction of " + port, e);
return false;
}
}
}
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