code:

using UnityEngine;
using System.Collections;

// 0.32409035f
[RequireComponent(typeof(CharacterController))]
public class PlatformerController : MonoBehaviour {
  public float speed = 6.0F;
  public float jumpSpeed = 8.0F;
  public float gravity = 20.0F;
  private Vector3 moveDirection = Vector3.zero;
  private CharacterController controller;

  private float touchedSides = 0.0f;

  void Start() {
    controller = GetComponent<CharacterController>();
  }

  void FixedUpdate() {
    if(controller.isGrounded) {
      moveDirection = new Vector3(Input.GetAxisRaw("Horizontal"), 0, Input.GetAxisRaw("Vertical"));
      moveDirection = transform.TransformDirection(moveDirection);
      moveDirection *= speed;

      if(Input.GetButton("Jump"))
        moveDirection.y = jumpSpeed;
    }
    else {
      moveDirection.x = Input.GetAxisRaw("Horizontal") * speed;
      moveDirection.z = Input.GetAxisRaw("Vertical") * speed;

      if((controller.collisionFlags & CollisionFlags.Sides) != 0) {
        touchedSides = 0.0f;
      }

      if(touchedSides <= 0.1f && moveDirection.y <= 0.0f) {
        moveDirection.y = -1.0f;
        if(Input.GetButton("Jump")) {
          moveDirection.y = jumpSpeed;
        }
      }

      if((controller.collisionFlags & CollisionFlags.Above) != 0) {
        moveDirection.y = 0;
      }
    }

    moveDirection.y -= gravity * Time.fixedDeltaTime;
    controller.Move(moveDirection * Time.fixedDeltaTime);

    if((controller.collisionFlags & CollisionFlags.Sides) != 0) {
      GameObject.Find("Sides").guiText.text = "Touching";
    } else {
      GameObject.Find("Sides").guiText.text = "Not touching";
    }

    touchedSides += Time.fixedDeltaTime;
  }
}