Pi Rover: send POST data to Python script, http://goo.gl/tRcYrB

send.php

<?php

/* Pi Rover: Send POST data to Python script */
/* http://goo.gl/tRcYrB                      */

        const MINIMAL_SPEED = 65;
        const DELTA_SPEED = 75;

        const STOP = 0;
        const FORWARD = 1;
        const BACKWARD = 2;
        const FORWARD_LEFT = 3;
        const FORWARD_RIGHT = 4;
        const BACKWARD_LEFT = 5;
        const BACKWARD_RIGHT = 6;
        const ROTATE_LEFT = 7;
        const ROTATE_RIGHT = 8;
        const SPEED_LEFT = 9;
        const SPEED_RIGHT = 10;

$send = '/home/helfrich/send.py';
error_reporting(E_ALL);
//header('Content-type: application/json');
//echo json_encode($_POST);
$command = $_POST['command'];
$speed = $_POST['data'];

echo $command;

switch ($command) {
    case STOP:
        exec($send . " 194 0 >/dev/null &");
        exec($send . " 202 0 >/dev/null &");
        break;
    case FORWARD:
        exec($send . " 194 " . $speed . " >/dev/null &");
        exec($send . " 202 " . $speed . " >/dev/null &");
        break;
    case BACKWARD:
        exec($send . " 193 " . $speed . " >/dev/null &");
        exec($send . " 201 " . $speed . " >/dev/null &");
        break;
    case FORWARD_LEFT:
        $speed = rotation_speed($speed);
        $speed_right = $speed;
        $speed_left = $speed - DELTA_SPEED;
        if ($speed_left < 0) {
            $speed_left = 0;
        }
        //print $speed_right . PHP_EOL;
        //print $speed_left . PHP_EOL;
        exec($send . " 194 " . $speed_right . " >/dev/null &");
        exec($send . " 202 " . $speed_left . " >/dev/null &");
        break;
    case FORWARD_RIGHT:
        $speed = rotation_speed($speed);
        $speed_right = $speed - DELTA_SPEED;
        if ($speed_right < 0) {
            $speed_right = 0;
        }
        $speed_left = $speed;
        exec($send . " 194 " . $speed_right . " >/dev/null &");
        exec($send . " 202 " . $speed_left . " >/dev/null &");
        break;
    case BACKWARD_LEFT:
        $speed = rotation_speed($speed);
        $speed_right = $speed;
        $speed_left = $speed - DELTA_SPEED;
        if ($speed_left < 0) {
            $speed_left = 0;
        }
        exec($send . " 193 " . $speed_right . " >/dev/null &");
        exec($send . " 201 " . $speed_left . " >/dev/null &");
        break;
    case BACKWARD_RIGHT:
        $speed = rotation_speed($speed);
        $speed_right = $speed - DELTA_SPEED;
        if ($speed_right < 0) {
            $speed_right = 0;
        }
        $speed_left = $speed;
        exec($send . " 193 " . $speed_right . " >/dev/null &");
        exec($send . " 201 " . $speed_left . " >/dev/null &");
        break;
    case ROTATE_LEFT:
        $speed = rotation_speed($speed);
        exec($send . " 194 " . $speed . " >/dev/null &"); // right
        exec($send . " 201 " . $speed . " >/dev/null &"); // left backwards
        break;
    case ROTATE_RIGHT:
        $speed = rotation_speed($speed);
        exec($send . " 193 " . $speed . " >/dev/null &"); // right backwards
        exec($send . " 202 " . $speed . " >/dev/null &"); // left 
        break;
    case SPEED_LEFT:
        if ($speed > 0) {
            exec($send . " 202 " . $speed . " >/dev/null &");
        } else {
            $speed = - $speed;
            exec($send . " 201 " . $speed . " >/dev/null &");
        }
        break;
    case SPEED_RIGHT:
        if ($speed > 0) {
            exec($send . " 194 " . $speed . " >/dev/null &");
        } else {
            $speed = - $speed;
            exec($send . " 193 " . $speed . " >/dev/null &");
        }
        break;
}

function rotation_speed($speed) {
    $speed = $speed + 10;
    if ($speed > 100) {
        $speed = 100;
    }
    return $speed;
}

function stop() {

    global $send;

    exec($send . " 194 0 >/dev/null &");
    exec($send . " 202 0 >/dev/null &");
}

?>