WEBVTT 00:00.320 --> 00:06.230 Finally, we can try out our transmitter node and see how we can communicate with the Arduino board 00:06.260 --> 00:07.340 through the Ros. 00:07.340 --> 00:08.270 Two topics. 00:08.300 --> 00:11.660 In order to turn a Led on or off. 00:12.400 --> 00:13.360 To do this. 00:13.390 --> 00:18.400 First, let's connect the Arduino board to our PC using an USB cable. 00:22.620 --> 00:28.080 Then open the Arduino IDE to check which port the board is connected to. 00:28.170 --> 00:30.210 So in the tools. 00:31.140 --> 00:31.830 Port. 00:32.070 --> 00:36.060 In my case, this is the ACM zero port. 00:36.980 --> 00:42.170 And then since we have already uploaded the code to the Arduino board in the previous lesson, we no 00:42.170 --> 00:49.520 longer need the Arduino IDE so we can proceed to start our transmitter node, which reads the messages 00:49.520 --> 00:54.290 from our ros2 topic and sends them through the serial port to the Arduino. 00:54.740 --> 00:58.730 So let's open a new terminal and let's go to the workspace. 00:58.970 --> 01:03.680 And here let's source the file setup dot bash. 01:03.680 --> 01:12.200 So source the workspace and let's start our Ros two node with the command Ros two run and from the Arduino 01:12.200 --> 01:14.510 bot firmware package. 01:14.510 --> 01:18.380 Let's start the simple serial transmitter node. 01:18.470 --> 01:22.940 Now with this, I'm going to start the cplusplus implementation of this node. 01:22.970 --> 01:29.690 Otherwise, if you want to launch the Python implementation of this node, let's just type dot pi. 01:30.080 --> 01:33.650 And so this one will launch the Pi implementation of this node. 01:34.310 --> 01:40.410 Also before starting the node it needs to be configured, so we need to assign a value to the parameter 01:40.410 --> 01:41.100 port. 01:41.130 --> 01:48.720 So let's use the Ros args and then let's assign a parameter to the port. 01:49.170 --> 01:53.580 And this is the port of your PC to which the Arduino is connected. 01:53.580 --> 02:01.020 So in my case this is the M0 port, so let's press enter. 02:01.170 --> 02:07.470 And upon starting this node it does nothing but initialize the serial communication with the Arduino 02:07.470 --> 02:09.000 on the indicated port. 02:09.000 --> 02:11.430 So on the ACM zero port. 02:11.790 --> 02:16.950 Additionally, the node is also listening on a Ros two topic called Serial Transmitter. 02:17.070 --> 02:23.130 In fact, if we open a new terminal and we execute the command Ros two topic list. 02:23.980 --> 02:32.680 We can see that the serial transmitter topic exists and so we can use it to turn on or off the light 02:32.680 --> 02:34.450 that is embedded in the board. 02:34.780 --> 02:40.290 To do so, we can use the command Ros2 topic Poop. 02:41.120 --> 02:46.130 And so let's publish a message on the serial transmitter. 02:46.160 --> 02:48.200 Then let's press tab twice. 02:48.320 --> 02:51.530 And then let's type the type of the interface. 02:51.530 --> 02:57.130 So the standard message string that we are going to use in order to send messages within this topic, 02:57.140 --> 02:58.970 then use the double quotes. 02:59.000 --> 03:03.500 Then let's type the letter D and let's press tab again. 03:03.500 --> 03:09.080 And so this will insert an empty prototype of the string message which we can publish on the serial 03:09.080 --> 03:10.280 transmitter topic. 03:10.490 --> 03:16.310 For example, let's turn on the led by publishing the value one on this topic. 03:16.310 --> 03:18.170 So let's press enter. 03:18.170 --> 03:22.310 And as soon as we do so we can see, we can interrupt this one. 03:22.310 --> 03:27.620 We can see that the Led that is integrated into the board is on now is turned on. 03:28.230 --> 03:33.600 If we send another message, for example, now let's send the message zero. 03:33.960 --> 03:35.760 So let's send it. 03:35.760 --> 03:41.280 And now we can see that as soon as we send this message, the lead that is embedded in the board is 03:41.280 --> 03:42.240 turned off.