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ROS Tutorial
===============================================================================

## Build Environment
- Ubuntu
- ROS indigo
- python 2.7


## Install ROS
Please check [this page](http://wiki.ros.org/Documentation) and install ROS to your PC that is installed ubuntu.

### Create a Workspace
Please create a working directory to develop with ROS.
After that, initialize the working directory environment as follows:

```bash
$ mkdir -p ~/catkin_ws/src
$ cd ~/catkin_ws/src
$ catkin_init_workspace
$ cd ~/catkin_ws
$ catkin_make
```

There is a setup script to initialize the environment.
Please enter command below.

```bash
$ source ~/catkin_ws/devel/setup.bash
```

This process needs at first time whenever use ROS. Thus, I recommend to add script to **.bashrc** file.

```bash
#source /opt/ros/indigo/setup.bash
source ~/catkin_ws/devel/setup.bash
```

### Create a Package
Please change directory and create a package.

```bash
$ cd ~/catkin_ws/src
```

```bash
$ catkin_create_pkg <YOUR_PACKAGE_NAME> rospy roscpp std_msgs
```

And then, run `catkin_make` again.

```bash
$ cd ~/catkin_ws
$ catkin_make
$ source ~/catkin_ws/devel/setup.bash
```

Now, your package can be available.
Please check it with following command:

```bash
catkin_ws$ roscd <YOUR_PACKAGE_NAME>
catkin_ws/src/<YOUR_PACKAGE_NAME>$
```

If you can do it, creating a package is succeeded.


## Connect to PLEN2
Since time of the shipment, PLEN2 has been access point mode (You could connect PLEN2 as WiFi).
Also PLEN2 has been set different SSID and common password.

```
SSID: PLEN2dev<PLEN2_MAC_ADDRESS>
Password: plenproject
```


## Setting Up ROS Environment
After connect your PC to PLEN2, please check IP address of your PC with `ifconfig` command.
Then, change ROS environment parameters as follows:

```bash
export ROS_IP=<PC_IP_ADDRESS>
export ROS_HOSTNAME=<PC_IP_ADDRESS>
export ROS_MASTER_URI=http://192.168.42.1:11311
```

Now, your PC can communicate other ROS setuped devices.


## Blink LED of PLEN2's Eyes
Let you blink LED of PLEN2's eyes.
Please create following sample program.

```python
#!/usr/bin/env python
# -*- coding: utf-8 -*-

import rospy
from std_msgs.msg import String


def talker():
    rospy.init_node('PCNode', anonymous=True)

    p = rospy.Publisher('PcToControl', String, queue_size=10)
    r = rospy.Rate(1)

    led_command = String()
    led_command.data = 'gpio,w,off'

    while ( not rospy.is_shutdown() ):
        if ( 'on' in led_command.data ):
            led_command.data = 'gpio,w,off'

        elif ( 'off' in led_command.data ):
            led_command.data = 'gpio,w,on'

        rospy.loginfo('%s', led_command.data)

        p.publish(led_command)
        r.sleep()


if __name__ == '__main__':
    try:
        talker()

    except rospy.ROSInterruptException:
        pass
```

This script blink PLEN2's eye at every seconds.
PLEN2 subscribe topic which name is **PcToControl**.

You need to run following command to be availabel the python script:

```bash
$ chmod 755 <CREATED_SCRIPT_NAME>
$ python <CREATED_SCRIPT_NAME>
```

In addition, You could control PLEN2 with command below. [See also...](http://plen.jp/playground/wiki/specifications/protocol)

```
serial,w,<ANY_PROTOCOL_OF_PLEN2>
```

For example, if you would like to play the motion that is placed slot 4, send command below:

```
serial,w,$pm04
```
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