WEBVTT 00:00.140 --> 00:04.190 This is step number five of the final project of this course. 00:04.190 --> 00:10.310 And now that we have the Arduino code finished and tested, let's write the code on the Raspberry Pi 00:10.310 --> 00:11.270 with Python. 00:11.270 --> 00:14.060 So the step five is going to be with Python. 00:14.240 --> 00:22.520 Now we are going to use the Raspberry Pi functionalities and also the application logic to define, 00:22.550 --> 00:29.390 okay, what the application will do and of course to interact with the Arduino so we can translate this 00:29.390 --> 00:33.440 application logic into real physical actions. 00:33.440 --> 00:37.820 And we're going to use a slightly different method for the steps here. 00:37.820 --> 00:43.070 So for the Arduino, we just initialize the component and then did the input commands and the output 00:43.070 --> 00:49.310 commands on the Raspberry Pi, we are going to follow the logical order of the user journey. 00:49.310 --> 00:52.550 So the user is basically who is using the application. 00:52.550 --> 00:52.790 Okay. 00:52.790 --> 00:58.970 Because here, as we are writing the application logic, well this is going to be a better way so we 00:58.970 --> 01:05.430 can iterate every time on the next step so we can validate one step and then iterate on the next one. 01:05.430 --> 01:10.950 And so first of all, well, in this step we are going to initialize serial communication. 01:10.950 --> 01:16.350 We're going to send the message on the LCD to give the information that you have to press on the push 01:16.350 --> 01:18.630 button and we're going to read from the push button. 01:18.630 --> 01:23.220 So at the end of this step, we will be able to know when we have pressed on the push button from the 01:23.220 --> 01:24.060 Raspberry Pi. 01:24.060 --> 01:27.120 And then in the following steps, we are going to take a photo. 01:27.120 --> 01:34.140 When the button is pressed, we are going to send that photo and a message to the telegram, chat with 01:34.140 --> 01:41.220 the telegram bot and then we will write the code to open the door and we will write the code to deny 01:41.220 --> 01:42.390 the access. 01:42.540 --> 01:46.860 And so those are going to be step five to step nine. 01:47.250 --> 01:47.670 All right. 01:47.670 --> 01:48.840 And let's get started. 01:48.840 --> 01:57.810 So here I'm going full screen with Python and I keep that on the side to check the Arduino code and 01:57.810 --> 02:00.360 change something if eventually we need to change something. 02:00.360 --> 02:02.160 But I think that should be good. 02:02.430 --> 02:02.850 All right. 02:02.850 --> 02:05.730 So let's write the very beginning. 02:06.180 --> 02:07.860 So the interpreter. 02:10.500 --> 02:10.830 Okay. 02:10.830 --> 02:14.670 And then we are going to import serial library. 02:15.210 --> 02:20.010 And also let's import time directly because we are going to need to use it. 02:20.220 --> 02:26.190 So the first thing we do is to init serial communication with. 02:26.220 --> 02:32.520 So let's say cell is equal to serial dot serial. 02:33.270 --> 02:34.830 Then the port. 02:34.860 --> 02:47.610 Let's actually find the device name ls slash dev slash y and all the options we have that one. 02:47.610 --> 02:49.350 That should be the arduino. 02:49.710 --> 02:53.850 So slash dev slash tty ACM zero. 02:54.690 --> 02:58.380 The baud rate is the same. 02:59.650 --> 03:00.910 And right there. 03:02.240 --> 03:04.730 115,002 hundred. 03:05.060 --> 03:06.680 And then let's put a timeout. 03:06.780 --> 03:09.530 Read timeout of one second. 03:09.740 --> 03:15.140 And so for this project, we're not just going to connect to sales like this, we're going to put that 03:15.140 --> 03:17.690 inside a try except. 03:19.480 --> 03:21.770 So except cereal. 03:21.820 --> 03:23.350 Dot cereal. 03:24.010 --> 03:27.750 Exception in case that we can't connect and we're going to retry. 03:27.760 --> 03:30.850 And so to retry, I'm going to put a while here. 03:31.180 --> 03:36.910 While true but that's inside the while true. 03:37.120 --> 03:50.140 So if it works we do print successfully connected to cereal and we break out of the while. 03:50.140 --> 04:00.100 If it doesn't work we do print could not connect to cereal retrying. 04:02.080 --> 04:04.480 In one second, two seconds. 04:04.480 --> 04:05.020 Whatever. 04:07.660 --> 04:17.890 And then of course time dot sleep with one here and let's add another log here actually print to make 04:17.890 --> 04:18.970 it more complete. 04:20.260 --> 04:24.610 Trying to connect to Serial. 04:25.480 --> 04:25.660 Okay. 04:25.660 --> 04:31.540 So we have first trying to connect to cell and then successfully connected or could not connect retrying 04:32.080 --> 04:44.230 after we are so when we reach line 16 here let's just put the wait so wait after setup and let's just 04:44.230 --> 04:49.660 put print waiting for three seconds. 04:52.720 --> 04:52.800 Okay. 04:52.870 --> 04:54.550 So we know we have to wait. 04:55.090 --> 04:57.520 So time dot sleep. 04:57.520 --> 05:05.020 We give some time for the Arduino to be ready, especially now that we also have, as you can see in 05:05.020 --> 05:06.890 the setup, we have a delay. 05:06.910 --> 05:07.990 One second. 05:08.020 --> 05:08.530 Okay. 05:09.870 --> 05:15.820 So the time that the cell is initialized and plus this one second, we're just going to wait for three 05:15.820 --> 05:16.920 seconds on the Raspberry Pi. 05:16.920 --> 05:21.090 So we know that after those three seconds, everything is okay. 05:21.390 --> 05:27.810 And I'm going to do self dot reset input buffer. 05:28.560 --> 05:34.380 So anything that was received from the Arduino before those three seconds is going to be discarded. 05:35.160 --> 05:36.690 And then let's say print. 05:37.710 --> 05:38.370 Okay. 05:39.510 --> 05:47.370 What we can do also we'll just after we have initialized the serial and waited for three seconds, is 05:47.370 --> 05:50.220 to send actually two commands to the Arduino. 05:50.250 --> 05:55.860 Because when we start the application, if you remember, we have something on the screen that says 05:55.860 --> 05:57.930 push on the button to call. 05:57.930 --> 06:00.870 And we also have the Led, which is blue. 06:01.350 --> 06:01.460 Okay? 06:01.620 --> 06:04.920 So blue is basically the waiting state. 06:05.190 --> 06:12.130 And so before we write any while loop here, we're going to add some comments. 06:12.130 --> 06:27.670 So cell dot write, we're going to do print, text, push on button to call with backslash and of course 06:27.700 --> 06:33.220 dot encode UTF eight. 06:34.410 --> 06:36.420 Who's better with quotes. 06:37.780 --> 06:41.170 Like this and say that right. 06:41.710 --> 06:45.520 So we just send the two commands one after the other. 06:45.920 --> 06:46.060 Okay. 06:46.060 --> 06:47.770 So the first command is going to be. 06:47.860 --> 06:57.270 So with the read string here, read string until backslash N is going to read this until backslash n 06:57.280 --> 06:58.660 So it's going to get that. 06:58.780 --> 07:03.370 And then the other command is going to be in the buffer of the Arduino and it's going to be read just 07:03.370 --> 07:04.150 after it. 07:04.150 --> 07:09.460 And because we go very fast in the void loop, it's just like we are going to execute the two commands 07:09.460 --> 07:10.600 at the same time. 07:10.750 --> 07:18.880 Let's do set Led and let's put 000 and then so red, green, blue. 07:19.960 --> 07:27.940 With backslash n and encode UTF eight. 07:29.350 --> 07:29.920 All right. 07:29.920 --> 07:34.570 And as you can see, well, we're going to send a few comments to the Arduino from the Raspberry Pi. 07:34.570 --> 07:36.520 And every time we need to do that, say that. 07:36.520 --> 07:37.210 Right. 07:37.210 --> 07:42.450 So we have the command, but we need also to add the backslash n and do encode. 07:42.460 --> 07:49.120 So what I'm going to do is I'm going to create a function here, just a function after we initialize 07:49.120 --> 07:57.310 sale def sent to Arduino with the text we want to send to Adrian. 07:57.490 --> 07:57.730 Okay. 07:57.730 --> 08:03.790 So then instead of just doing self dot right, we just do send to Arduino with the command directly. 08:03.790 --> 08:07.690 We don't need to worry about the backslash n about the encoding etcetera. 08:07.690 --> 08:09.580 And so we are going to construct a string. 08:09.580 --> 08:15.430 So string to send is equal to text plus backslash. 08:15.430 --> 08:23.600 N Actually I'm going to do text dot strip, just in case we send something with some backslash and character, 08:23.600 --> 08:24.710 some carriage return. 08:24.710 --> 08:29.030 We're going to remove them to be sure there is none and then we're going to add one. 08:29.030 --> 08:41.090 So we only have one backslash n at the end and then say dot write string to send dot encode UTF eight. 08:41.990 --> 08:42.830 All right. 08:43.550 --> 08:48.920 And so we're going to save a bit of code and make less mistakes when we need to send something to the 08:48.920 --> 08:49.430 Arduino. 08:49.430 --> 08:55.700 And so I'm going to do send to Arduino with just this. 08:59.000 --> 08:59.450 Okay. 08:59.450 --> 09:06.440 And then send to Arduino with set led until there. 09:09.810 --> 09:10.290 Okay. 09:10.290 --> 09:11.430 And I can remove that. 09:11.430 --> 09:13.590 And the code is now a bit cleaner. 09:14.580 --> 09:21.300 And well, one iteration you could also add is add other functions on top of that, for example, print 09:21.300 --> 09:23.290 text on Arduino set LCD. 09:23.550 --> 09:29.280 And so you're going to construct the string directly, for example, print text on a function and you 09:29.280 --> 09:33.620 just need to send this text or you just need to send the colors. 09:33.630 --> 09:36.780 And so you can have one function for each command you send. 09:36.780 --> 09:43.410 But I'm going to keep things simple here and just send the entire command, but without having to worry 09:43.410 --> 09:46.830 about this backslash n at the end and the encoding. 09:47.400 --> 09:49.670 So now everything is okay. 09:49.680 --> 09:53.880 We have put some text on the screen and set the Led. 09:54.480 --> 09:57.240 What we're going to do is the while loop. 09:57.240 --> 10:03.660 So all of that is kind of the void setup, okay, of the Raspberry Pi and then the void loop is going 10:03.660 --> 10:06.390 to be the next block of code. 10:06.690 --> 10:16.920 And so let's put run main loop, maybe let's put okay and then main loop is starting. 10:19.190 --> 10:22.960 So we do the while true. 10:22.970 --> 10:29.720 Let's put directly time dot sleep for 0.01 second. 10:29.750 --> 10:32.480 So we're going to run this loop at 100Hz. 10:32.690 --> 10:36.050 And let's put directly this inside. 10:36.260 --> 10:45.440 So I'm going to put more spaces here inside a try except structure. 10:48.150 --> 10:49.380 Except keyboard 10:52.140 --> 10:53.220 interrupt. 10:53.760 --> 10:55.140 And what do we do here? 10:55.140 --> 11:11.030 We do say dot close with a message, print closing, cell communication, and then let's say print end 11:11.070 --> 11:12.210 of program here. 11:15.120 --> 11:20.190 And maybe we can also add before I'm going to add dash, dash, dash. 11:20.190 --> 11:25.350 So basically every log that we're going to print, then we have dash, dash, dash, which makes a clear 11:25.350 --> 11:26.940 separation for the end. 11:26.970 --> 11:31.920 It's just for us, the developer to get nicer logs when we run the application. 11:31.920 --> 11:32.460 Okay. 11:32.820 --> 11:37.800 So we have this cell is correctly handled. 11:37.800 --> 11:45.900 And now let's do if, say, dot in waiting, because let's not forget what we want is to receive the 11:45.930 --> 11:48.060 button pressed command. 11:48.060 --> 12:00.990 So if we have something in the serial we do message is equal to set dot read line dot decode, UTF eight 12:02.280 --> 12:04.110 dot strip. 12:05.130 --> 12:12.000 So here you could also create a function like receive line from Arduino or something like that. 12:12.390 --> 12:17.820 But as we are only going to get one command, well, I'm just going to leave that code here. 12:17.820 --> 12:23.430 But if you were to use this pretty often, then creating a function would be a good idea. 12:23.430 --> 12:31.740 And let's do if message is equal to button pressed, let's check that we have. 12:32.570 --> 12:33.490 Button pressed. 12:33.500 --> 12:36.200 That's the same in that case. 12:36.230 --> 12:37.520 Let's do print. 12:38.660 --> 12:43.700 Open the request, because that's what this means. 12:44.210 --> 12:49.460 And then what we're going to do is we're going to take a photo with the camera, send it to Telegram. 12:49.460 --> 12:51.800 But that's for the next step. 12:52.040 --> 12:59.790 What we could already do is to send to Arduino the command to print some text. 12:59.810 --> 13:01.940 So print text. 13:02.570 --> 13:10.200 So basically to give the user the information, the feedback that, well, the request has been received. 13:10.240 --> 13:10.690 Okay. 13:10.700 --> 13:15.110 If you press on the button and nothing happens, well, you can't know if it worked. 13:15.110 --> 13:21.890 So if you press on the button and you see the text, like, please wait a few seconds, then you know 13:21.890 --> 13:23.810 that the request has been sent. 13:23.810 --> 13:26.540 So we're going to change the text. 13:26.580 --> 13:34.010 Can the LCD please wait for a few seconds? 13:34.010 --> 13:34.230 Okay. 13:34.250 --> 13:37.130 And then we are going to handle the request. 13:37.130 --> 13:43.790 And when we decide to open the door or to deny the access, we're going to also change the text. 13:43.820 --> 13:46.150 But that's for a future step. 13:46.160 --> 13:50.630 For now, we just acknowledge that we have received the request. 13:50.840 --> 13:58.640 And I'm going to add also an else here because as we did for the Arduino, so on the Arduino, we read 13:59.330 --> 14:00.560 a string. 14:00.560 --> 14:07.430 And if the string doesn't correspond to anything that we expect, we clear the input buffer. 14:07.430 --> 14:08.810 We're going to do the same here. 14:09.200 --> 14:17.630 If we receive something that is not button pressed, then we're going to do set dot reset input buffer. 14:17.630 --> 14:19.760 So we just clear everything else. 14:19.760 --> 14:25.640 And so we give another chance to read correct data when we enter the while loop again. 14:26.330 --> 14:35.130 Okay, Now let's save this program as intercom, let's say step and we are in step number five. 14:35.670 --> 14:38.850 Okay, so the Python program will actually start at step five. 14:38.880 --> 14:39.210 Okay. 14:39.240 --> 14:42.570 The Arduino is going to be step two, three and four. 14:42.870 --> 14:47.880 And for the Python program, we will have step five, six, seven, eight and nine. 14:47.880 --> 14:49.590 And let's save this. 14:49.950 --> 14:57.330 So the program here, the Arduino program is still uploaded and running on the Raspberry Pi. 14:57.540 --> 15:00.120 Now we can run this. 15:00.300 --> 15:02.760 So let's run the code on the Raspberry Pi. 15:02.790 --> 15:04.050 Successfully connected. 15:04.050 --> 15:05.820 You can see starting here. 15:05.850 --> 15:10.110 Okay, Main loop is starting and you can see push on button to call. 15:10.140 --> 15:11.520 The Led is blue. 15:11.850 --> 15:15.210 Push on the button you can see open door request. 15:15.210 --> 15:19.050 We have received a log here and please wait for a few seconds. 15:19.050 --> 15:26.430 So we have correctly received the information that someone is ringing the bell and that's the end of 15:26.430 --> 15:26.640 this. 15:26.640 --> 15:27.840 Step number five.