WEBVTT 00:00.080 --> 00:06.590 In this new activity, you are going to do a bi directional communication between the Arduino and the 00:06.590 --> 00:07.520 Raspberry Pi. 00:07.550 --> 00:13.070 And your challenge is that when you press on the push button on the Arduino side, so you're going to 00:13.070 --> 00:14.930 read the push button. 00:14.930 --> 00:19.550 When you detect that the push button is pressed, you send a message to the Raspberry Pi. 00:19.820 --> 00:27.170 The Raspberry Pi will receive that message, will check that it corresponds to a button pressed message 00:27.170 --> 00:29.960 and then it will choose a random led. 00:30.080 --> 00:36.710 So the red, the green or the blue, and it will choose a random number between 0 and 255, and it will 00:36.710 --> 00:38.750 send that back to the Arduino. 00:38.750 --> 00:44.180 And then the Arduino is going to process this command and power on accordingly. 00:44.210 --> 00:50.510 One of the color of the RGB led with the number that we have received with Analogwrite. 00:50.540 --> 00:50.840 Okay. 00:50.840 --> 00:54.350 So on the Arduino side, you're going to have two actions. 00:54.350 --> 00:57.140 The first is to read the push button. 00:57.170 --> 00:59.720 The second is to read the sale. 00:59.720 --> 01:02.850 So you read the push button, you send the message to the RPI. 01:02.880 --> 01:09.180 So the Raspberry Pi and here, when I'm not going to tell you what exact message you need to send, 01:09.180 --> 01:16.380 okay, I'll leave that up to you so you can practice on defining a good protocol for sending and receiving 01:16.380 --> 01:19.040 data and then, well, for the lead. 01:19.050 --> 01:22.770 I have given you an example here because that's maybe a little bit more complex. 01:22.770 --> 01:24.180 So I give you an example. 01:24.180 --> 01:30.270 First, what you can do, for example, is if you send a command to power on so to change the color 01:30.270 --> 01:36.900 on the red led, then you can send something that starts with red colon and then the color, for example, 01:37.380 --> 01:38.460 56 like this. 01:38.460 --> 01:44.220 Okay, If you send something with the green, then you're going to do green colon color, okay? 01:44.220 --> 01:46.020 And blue color, etcetera. 01:46.020 --> 01:47.820 And so you can send that from the Raspberry Pi. 01:47.820 --> 01:51.540 And then on the Arduino, what you can do instead of comparing. 01:51.540 --> 01:57.180 So the equality with string, which you can't do because you don't actually know what number you're 01:57.180 --> 01:58.920 going to get, this is valuable. 01:58.920 --> 02:05.010 You can do comments, starts with and then the name of the command colon. 02:05.250 --> 02:05.520 Okay. 02:05.520 --> 02:11.700 If this starts with this, then you're going to process this and how to extract the number that is here. 02:11.730 --> 02:14.160 Well, you can first do command dot remove. 02:14.160 --> 02:19.050 So this is going to remove the first here, the first part of the string. 02:19.050 --> 02:22.680 So you have index zero, one, two, three and four. 02:22.680 --> 02:28.350 So this is going to remove completely this part and you're just left with the number, but the number 02:28.350 --> 02:29.430 is still a string. 02:29.430 --> 02:29.820 Okay? 02:29.820 --> 02:30.840 Because you receive a string. 02:30.840 --> 02:32.250 So the number is still a string. 02:32.250 --> 02:37.890 So then you do command dot to INT and the result of that is going to go inside an integer, right? 02:37.890 --> 02:40.410 That you can use then with analogwrite. 02:40.440 --> 02:40.710 Okay. 02:40.710 --> 02:43.290 And you can do the same with green and the same with blue. 02:43.290 --> 02:45.420 Now on the Raspberry Pi side. 02:45.420 --> 02:49.520 So you're going to initialize a serial and then you're going to do a while. 02:49.560 --> 02:51.390 True like we did before. 02:51.510 --> 02:55.380 And you're going to check if you receive some comment from the Arduino. 02:55.380 --> 02:58.410 If you receive something, you check if the button has been pressed. 02:58.410 --> 03:01.800 If yes, then you're going to choose a random number. 03:01.800 --> 03:04.080 So between 0 and 2. 03:04.470 --> 03:04.830 Okay. 03:04.830 --> 03:10.440 So that you can have zero 1 or 2, which means red, green or blue, and then you're going to choose 03:10.440 --> 03:17.370 another number with zero and 255, you are going to construct a string. 03:17.400 --> 03:17.670 Okay? 03:17.670 --> 03:20.700 That corresponds to the command you're going to send to the Arduino. 03:20.700 --> 03:27.300 So to choose a random number, you can well just import random and then do random dot rand int like 03:27.300 --> 03:29.640 this with the minimum and the maximum. 03:29.640 --> 03:29.940 Okay. 03:29.940 --> 03:36.240 And this activity is actually a good example of how to use the combination of Raspberry Pi and Arduino 03:36.600 --> 03:41.130 for a complete application where the Arduino is basically the muscle of the application. 03:41.130 --> 03:41.550 Okay. 03:41.550 --> 03:46.920 It's going to read from sensor, it's going to actuate some sensor, but it's not going to decide what 03:46.920 --> 03:47.340 to do. 03:47.340 --> 03:50.940 And then the Raspberry Pi here decides on what to do. 03:50.940 --> 03:54.240 So the Raspberry Pi is actually the brain of the application. 03:54.240 --> 03:56.280 So you have the brain and the muscle. 03:56.280 --> 04:02.100 And basically that's how things work in many different projects with those two balls. 04:02.310 --> 04:06.660 Okay, so now I'm going to see you in the next video for The Solution.