WEBVTT 00:00.080 --> 00:05.630 I will separate this solution into three different videos, so it will be easier for you to follow. 00:05.660 --> 00:12.170 First, in this video, the first one, I will create the LED panel node and publish the LED panel state 00:12.170 --> 00:14.570 with a custom message type. 00:14.600 --> 00:21.170 In the second video, I will create the service server inside the LED panel using also a custom service 00:21.170 --> 00:21.860 type. 00:21.860 --> 00:27.860 And in the third video that's going to be the battery node which will call the set LED server. 00:27.860 --> 00:33.200 And once again I do the solution in Python and you can download the complete C plus plus code at the 00:33.200 --> 00:34.370 end of the section. 00:34.370 --> 00:35.660 So let's get started. 00:35.660 --> 00:41.450 We first want to create a custom interface because we want to publish an LED panel state. 00:41.450 --> 00:43.550 And for that we need a custom message. 00:43.550 --> 00:46.010 So that's the first thing we need to create. 00:46.040 --> 00:51.890 Let's go to our workspace and then to our Myrobot interfaces. 00:51.890 --> 00:57.470 And here we are going to create a new message inside the MSG folder. 00:57.470 --> 00:59.090 And I'm going to name it. 00:59.090 --> 01:06.350 So let's do touch LED state Array dot msg. 01:06.440 --> 01:06.890 Okay. 01:06.920 --> 01:10.460 And I just start each word here with an uppercase. 01:10.460 --> 01:13.160 And then I use lowercase for all the other letters. 01:13.400 --> 01:14.180 All right. 01:14.210 --> 01:17.000 Now let's go to VS code. 01:18.470 --> 01:20.810 I'm going to open VS code here. 01:21.770 --> 01:24.680 And let's create that interface. 01:26.060 --> 01:28.430 So I'm going to close all of that. 01:28.430 --> 01:32.900 And in MSG we have led state array. 01:32.930 --> 01:39.230 So what I'm going to do is simply to create a list of integer numbers for the LED state. 01:39.260 --> 01:43.700 To create a list of integer numbers I can put int 64. 01:43.730 --> 01:44.510 That's the type. 01:44.510 --> 01:51.230 And then those brackets to say it's a list and I'm going to name them LED states for example. 01:51.260 --> 01:51.500 Okay. 01:51.530 --> 01:55.880 So we're going to say that zero means off and one means on. 01:55.910 --> 01:57.740 We could have used booleans as well. 01:57.740 --> 02:00.830 But here I'm just using integers with zero and one. 02:00.860 --> 02:02.420 Let's save. 02:02.450 --> 02:02.690 Okay. 02:02.720 --> 02:04.280 So we just have one field. 02:04.340 --> 02:07.640 This is an array of integers. 02:07.640 --> 02:08.690 And that's it. 02:08.720 --> 02:10.790 Now we can build it. 02:10.820 --> 02:16.340 To build it, I'm going to go to Cmakelists.txt and add another line here. 02:16.340 --> 02:20.240 So I'm going to group all the messages and then all the services. 02:20.240 --> 02:23.180 It doesn't matter in the end but it's just a bit cleaner. 02:23.180 --> 02:31.010 So here I add another line MSG slash LED state array dot msg. 02:31.040 --> 02:32.840 Make sure you don't make any typo. 02:32.870 --> 02:37.460 Okay, for this file name let's save the Cmakelists.txt. 02:37.580 --> 02:38.750 And that's it. 02:38.780 --> 02:41.030 Okay we have created the interface. 02:41.030 --> 02:42.320 We add it here. 02:42.350 --> 02:43.910 Now we can build it. 02:44.930 --> 02:48.950 Let's do click on build packages. 02:49.760 --> 02:54.830 Select with my robot interfaces. 02:54.830 --> 03:00.080 You see I still have this warning log but I'm not doing anything wrong. 03:00.080 --> 03:02.510 So I'm just going to ignore that log. 03:03.500 --> 03:03.950 All right. 03:03.950 --> 03:08.150 And we have built the interface now because we have built the interface. 03:08.150 --> 03:12.690 We will need to source all the terminals where we want to be able to use it. 03:12.720 --> 03:18.150 We will also need to close VSCode and open it again from a terminal that is sourced. 03:18.150 --> 03:22.500 So I'm just going to close VSCode and I'm going to close all the terminals. 03:22.530 --> 03:22.890 Okay. 03:22.920 --> 03:25.410 I'm going to open terminals again. 03:27.180 --> 03:27.630 Okay. 03:27.630 --> 03:32.160 And then start VSCode from that folder. 03:33.120 --> 03:33.480 Okay. 03:33.510 --> 03:39.600 So then I can use my interface with the Autocompletion for Python and for C plus. 03:39.600 --> 03:45.930 Plus just a quick note for C plus plus you already have that line here okay in the C and cpp properties 03:45.930 --> 03:46.830 dot JSON. 03:46.830 --> 03:49.440 So for C plus plus it's also going to work. 03:49.560 --> 03:55.260 But first of all let's go in the terminal and let's see if we can find this interface Ros2 interface. 03:55.260 --> 03:59.700 Show my robot interfaces MSG. 03:59.700 --> 04:03.540 And then let's put an L with Autocompletion. 04:03.540 --> 04:05.310 We have led state array. 04:05.340 --> 04:05.820 Great. 04:05.820 --> 04:09.180 And if you can see that, it means that you can use your interface. 04:09.210 --> 04:13.200 If you cannot, you need to go back and make sure that everything is working. 04:13.200 --> 04:15.570 So now let's go here. 04:15.570 --> 04:22.710 And actually I'm going to create a new node because I want to create a node specially for the LED panel. 04:22.710 --> 04:34.260 So let's go to the Python package here and let's create that LED panel dot pi. 04:34.980 --> 04:39.570 Let's make it executable okay. 04:39.570 --> 04:42.300 And let's edit that file. 04:42.630 --> 04:51.450 So I don't need that anymore LED panel dot pi I'm going to take the template I don't need that. 04:52.830 --> 05:01.830 And let's put the template here and it's going to be LED panel node okay. 05:01.830 --> 05:04.080 And let's just call it LED panel. 05:06.120 --> 05:07.050 All right. 05:09.660 --> 05:18.030 And what I want to do here is to publish the states for all the LEDs in this LED panel Every X amount 05:18.030 --> 05:18.810 of time. 05:18.810 --> 05:26.070 So as you can probably guess, we need what we need a publisher and we need a timer to create a publisher 05:26.070 --> 05:27.510 I will need the interface. 05:27.510 --> 05:38.910 So let's import from my robot interfaces dot msg import led state array. 05:39.360 --> 05:49.110 Let's create a publisher here self dot led states publisher or just pub to take less space. 05:50.070 --> 05:58.560 We have self create publisher with the type led state array. 05:58.740 --> 06:00.000 That's the one here. 06:00.930 --> 06:02.610 Then the topic name. 06:02.760 --> 06:08.970 So let's call it LED panel state like the one I gave you in the challenge. 06:08.970 --> 06:11.820 And then we have a queue size. 06:12.060 --> 06:14.580 I'm just going to make it a bit cleaner okay. 06:14.610 --> 06:24.570 After that I'm going to create here in the class a method to publish LED states. 06:26.370 --> 06:31.440 Okay, I'm just going to put pass for now so that I can create a timer. 06:31.470 --> 06:36.360 Self dot LED states. 06:36.390 --> 06:39.390 Timer is equal to self dot. 06:39.390 --> 06:40.560 Create timer. 06:42.960 --> 06:48.090 And well let's say we want to publish every five seconds. 06:49.080 --> 06:49.320 Okay. 06:49.350 --> 06:52.590 We don't necessarily need that very often. 06:52.710 --> 06:56.280 So every five seconds we're going to publish the LED states. 06:56.580 --> 07:01.020 I put five and then self dot publish LED states. 07:01.020 --> 07:02.850 That's the callback. 07:02.880 --> 07:16.140 And finally let's add a log get logger info LED panel node has been started. 07:17.220 --> 07:17.490 Okay. 07:17.520 --> 07:21.630 And what do we do in this publish led state method. 07:21.630 --> 07:28.350 We're going to create a message of type LED state array. 07:28.680 --> 07:35.790 And this message here has a LED state field. 07:35.970 --> 07:36.180 Okay. 07:36.210 --> 07:39.750 If you are not sure you see we have it here from the terminal. 07:39.780 --> 07:41.730 You can also well you have written the code. 07:41.730 --> 07:44.280 So you can just go back to your interface and check that. 07:44.280 --> 07:48.720 And we also have the Autocompletion led state of type. 07:48.900 --> 07:51.990 Well that's the list of integers. 07:51.990 --> 07:58.830 So I'm going to initialize in the constructor I'm going to initialize self led state. 07:59.250 --> 08:03.420 And I'm going to initialize that to an array with three elements. 08:03.450 --> 08:06.300 Let's say we have three LEDs just like in the example I gave you. 08:06.300 --> 08:08.850 And those three LEDs are turned off. 08:08.880 --> 08:11.580 So once again zero means turned off. 08:11.580 --> 08:13.890 One would be turned on. 08:14.310 --> 08:14.610 All right. 08:14.610 --> 08:17.010 So now they are all turned off. 08:17.040 --> 08:20.160 We're going to see how to turn them on with a service. 08:20.160 --> 08:22.920 But for now we just publish the state as it is. 08:22.920 --> 08:29.050 So edit state is equal to self led states. 08:29.350 --> 08:32.590 And then we can do self dot led states. 08:32.590 --> 08:38.260 Publisher dot publish the message. 08:38.950 --> 08:39.220 Okay. 08:39.220 --> 08:46.330 So once again we have a very classic publisher and timer combo where we publish every X amount of time 08:46.330 --> 08:48.490 here every five seconds. 08:48.580 --> 08:50.170 So I'm going to save that. 08:50.170 --> 08:54.970 And let's create an executable here setup.py. 08:55.090 --> 09:08.110 I add a comma and then LED panel is equal to my pi pkg dot led panel with the main function. 09:08.290 --> 09:10.240 Okay let's go back here. 09:10.330 --> 09:18.700 Let's build the package called con build packages. 09:18.700 --> 09:22.180 Select with the Python one. 09:23.770 --> 09:27.550 And I'm also going to add the symlink install option here. 09:27.640 --> 09:31.390 So we can modify without having to build again. 09:31.990 --> 09:41.710 So now from this one, for example, let's use the terminal and let's do Ros to run my Pi PG with LED 09:42.010 --> 09:42.880 panel. 09:43.810 --> 09:44.260 Okay. 09:44.290 --> 09:46.000 The node has been started. 09:46.330 --> 09:50.140 Let's just source all the terminals here. 09:51.880 --> 09:52.360 Okay. 09:52.360 --> 09:55.780 And let's do a Ros two topic list. 09:56.350 --> 09:58.300 We should see our LED panel. 09:58.300 --> 10:01.060 State Ros two topic. 10:01.480 --> 10:04.930 Equal LED panel state. 10:06.460 --> 10:08.830 So it's publishing every five seconds. 10:08.830 --> 10:10.360 So you might need to wait a bit. 10:10.390 --> 10:11.500 You see we have one. 10:11.500 --> 10:16.060 And then we should have another one five seconds later etc.. 10:16.300 --> 10:18.400 And that's how you see an array. 10:18.430 --> 10:18.670 Okay. 10:18.700 --> 10:21.280 You see we have the name of the field. 10:21.280 --> 10:24.850 And then one element per line here with a dash. 10:24.850 --> 10:29.440 So when you do a ros2 topic that's how you're going to see lists of elements. 10:29.470 --> 10:30.010 Great. 10:30.010 --> 10:32.980 And the first step for this activity is finished.