WEBVTT 00:00.180 --> 00:06.450 This is step number three of the final project in this step, we are going to look at the application 00:06.450 --> 00:11.070 when the measured distance is lower than a certain threshold. 00:11.250 --> 00:18.330 So basically what this means is if you put this ultrasonic sensor in a real robot and mobile robot, 00:18.330 --> 00:24.030 for example, if there is an obstacle that is too close, you are going to make the robot stop and you 00:24.030 --> 00:30.960 are going to override the default behavior, but some warnings, et cetera, until the user removes 00:30.960 --> 00:33.840 the obstacle and unlock the application. 00:33.880 --> 00:40.560 OK, so in this step, only the lock functionality and in the next step we are going to unlock the application. 00:40.580 --> 00:43.960 So how to lock the application? 00:43.980 --> 00:52.890 I'm going to create a new boolean here, which is locked and set it to false by default. 00:53.370 --> 00:56.160 So this is a flag we are going to check and to set. 00:56.350 --> 00:58.390 And as you will see, it's quite easy. 00:58.920 --> 01:02.550 If we want to look at the application, we just set it to true. 01:02.820 --> 01:08.760 If we want to unlock, we set it to false and then we can just add in our code at some different places, 01:09.130 --> 01:09.510 Jake. 01:09.510 --> 01:12.540 If it's locked, if it's not locked and do some actions. 01:12.700 --> 01:14.610 I'm going to add also here. 01:16.480 --> 01:17.110 Define. 01:21.210 --> 01:28.590 Distance, OK, and let's say 10 centimeters, the ten point zero, so this is something you can change 01:28.890 --> 01:30.750 on your own application if you want to. 01:30.780 --> 01:34.980 OK, but for my application here, I'm going to use 10 centimeters. 01:34.980 --> 01:37.830 So below 10 centimeters, we lock the application. 01:38.130 --> 01:40.420 So I have my here, here. 01:40.440 --> 01:43.740 And what I can do now is actually the distance. 01:45.440 --> 01:52.350 When I get a new distance, I said so, I said some to break, etc., and then what I can do is check 01:52.370 --> 01:59.260 if distance is lower than not. 02:00.970 --> 02:07.930 Distance, if the distance is lower than the long distance we have defined, then I do is locked. 02:10.860 --> 02:15.840 And actually, what I'm going to do, I'm not going to just lock it here, I'm going to create a function 02:15.840 --> 02:25.580 called lock, so voided lock and in that function and who is locked is true. 02:26.040 --> 02:27.980 And actually, I'm going to do something else here. 02:27.990 --> 02:31.920 I'm going to check first if the application is not locked. 02:31.920 --> 02:41.110 So if exclamation mark is locked and only if it's not locked, I'm going to say it is locked to true 02:41.730 --> 02:43.700 and then call the lock function. 02:47.220 --> 02:52.340 So why use a function here, because, well, later on, you will be able to do more things, OK, and 02:52.350 --> 02:55.530 you can call the log if you want, from different parts of your application. 02:56.460 --> 03:01.200 And then in that function, you can see that first a check if is locked is false first. 03:01.440 --> 03:08.580 So this will enable us to only look at the application when it is not locked at because every time you 03:08.580 --> 03:14.180 but look to true and then you do some actions where you are going to do that many times here. 03:14.190 --> 03:20.490 By doing this, we ensure that we enter this book of code only when we go from the state, not logged 03:20.820 --> 03:22.200 to the state locked. 03:22.560 --> 03:22.830 All right. 03:22.830 --> 03:27.320 So we have a flag that is false, that is first and false. 03:27.330 --> 03:31.470 And then when the distance is lower than long distance, we set it to true. 03:32.040 --> 03:36.620 So the lock mechanism is already here, but now it's not doing anything. 03:36.630 --> 03:41.900 OK, so we need to do some action depending on if it's locked or not locked. 03:42.300 --> 03:48.480 What I'm going to do now is I'm going to say that when the state is locked, we're going to make the 03:48.480 --> 03:52.770 red and yellow and blink together at the same time. 03:53.190 --> 04:00.510 And this will of the right, the default behavior, for example, here, the one energy that is blinking 04:00.510 --> 04:02.520 at different rates will not happen. 04:02.520 --> 04:05.730 It will simply blink along with the right. 04:06.360 --> 04:10.370 So I'm going first to define here. 04:12.170 --> 04:17.390 Defined, so let's call it zero lead in 12. 04:18.480 --> 04:22.080 Let's add here some liabilities for. 04:23.710 --> 04:26.590 OP ed, that's just. 04:27.490 --> 04:38.560 Use the same thing here, so last time your energy blinked and then error added, delay willing to put 04:38.560 --> 04:39.820 that at three hundred. 04:41.330 --> 04:42.380 And in Iraq. 04:44.660 --> 04:50.300 And states, so we have our three variables to use the time, functionality and to be able to toggle 04:50.750 --> 04:54.410 the editing now and going also to add a function here. 04:54.420 --> 05:04.340 So we have toggle one managing to avoid toggle zero and can we create a separate function for that and 05:04.340 --> 05:06.450 the error state. 05:06.530 --> 05:08.690 So this function will toggle the state. 05:08.990 --> 05:13.170 So I'm going to use the one line if we are going to check. 05:13.190 --> 05:24.410 So there are any states, if the state is high interrogation match, we set it to low as we set it to 05:24.410 --> 05:28.200 high and then digital rights with that. 05:28.250 --> 05:28.790 There are. 05:30.710 --> 05:31.340 Naledi. 05:33.760 --> 05:36.010 And there are already state. 05:38.220 --> 05:39.990 And we have the Torgau, there are. 05:41.350 --> 05:43.390 So we were down in the city. 05:43.930 --> 05:50.910 I'm going to do spin mode zero in with about. 05:51.830 --> 05:58.910 It took initialise the pain and now what I'm going to do so now we are going to decide what we do when 05:59.180 --> 06:02.890 the application is locked, what we do when the application is not locked. 06:03.530 --> 06:06.000 Let's check each action we have here. 06:06.410 --> 06:10.050 So first, we trigger that ultrasonic sensor here and we measure the distance. 06:10.370 --> 06:11.860 This webbing to keep it OK. 06:12.020 --> 06:12.920 That is very important. 06:12.950 --> 06:13.850 We're going to keep that. 06:13.940 --> 06:21.830 And now this is the behavior of the one which is going to blink faster if the obstacle is closer. 06:22.340 --> 06:24.110 But we want to override this. 06:24.680 --> 06:31.250 What I'm going to do is if is locked, which we are going to do is make SilverLink. 06:33.370 --> 06:34.750 Errol and. 06:36.040 --> 06:47.110 One reads at the same time, so this would only happen if the flag is locked is true, and then else 06:49.060 --> 06:50.410 as I put this in the. 06:51.910 --> 06:55.290 And let's fix the incantation here. 06:57.580 --> 07:01.510 And actually, let's put this at the top of the loop. 07:02.620 --> 07:03.100 He. 07:05.740 --> 07:13.990 So now in the look, we first check if the flag is locked is true, then we do whatever we need to do 07:14.020 --> 07:20.460 when the application is logged, which would override some of the default behaviours that we put in 07:20.470 --> 07:20.590 the. 07:21.310 --> 07:23.560 So if the application is not logged, we do this. 07:23.560 --> 07:24.880 If it's locked, we do this. 07:25.450 --> 07:36.100 So what I'm going to do here is thank no minus last time you're all linked. 07:36.460 --> 07:41.050 If this is greater than zero editing delay. 07:43.700 --> 07:47.990 Then I'm going to do last time, plus delay. 07:50.000 --> 07:51.500 And I'm going to do toggled. 07:53.520 --> 08:00.600 Hero Eddie and I'm also going to do toggled one Eddie. 08:01.900 --> 08:07.300 So only if it's locked, I took a lead and a warning at the same time. 08:08.110 --> 08:12.790 Another thing is that you still set the warning, bring rates from the distance here. 08:13.300 --> 08:16.730 But this is actually used in that block of code. 08:16.900 --> 08:18.850 A warning allegedly here. 08:18.860 --> 08:24.770 We're going to talk about the warning energy depending on the eral and not the warning, evidently. 08:24.830 --> 08:26.520 So we don't really care about that line. 08:26.540 --> 08:28.310 We can just leave it like this. 08:28.810 --> 08:35.050 So now at 300, so this is three hundred defined here at three hundred milliseconds. 08:35.500 --> 08:39.480 Every three hundred milliseconds, we toggle the error and the warning reads. 08:39.820 --> 08:42.810 You can see the code here for the two functions will do the same thing. 08:43.300 --> 08:49.990 And just what I'm going to do is when we lock the application, so we set the flag to true, I'm going 08:49.990 --> 08:58.720 to do warning state, so I'm going to set the state to low and error state. 09:00.520 --> 09:06.680 So which means that I set the state for the two entities at the same so the same state. 09:06.700 --> 09:11.790 So then when I toggle it with toggle high and high and then low and low at the same time. 09:11.800 --> 09:19.600 OK, because what could happen here is that let's say so you first toggle the energy, so it's high, 09:19.600 --> 09:23.410 low, high, etc. and then you lock the application. 09:23.410 --> 09:30.690 When you lock the application, for example, the right LG is out and the yellow LCD is pulled on, 09:30.910 --> 09:38.140 which means that it's going to blink, but it's going to alternate between the yellow and red, which 09:38.140 --> 09:39.270 is maybe what you want to do. 09:39.280 --> 09:41.680 But in my case, it's not what I want to do. 09:41.680 --> 09:45.040 I want to make the league exactly at the same time. 09:45.340 --> 09:50.980 So I initialize also the state to the same state when I look at the application. 09:52.070 --> 09:59.420 So I think this is good, let's verify you could name it final project step three. 10:01.340 --> 10:03.890 OK, we don't have any compilation, Eros. 10:04.010 --> 10:05.810 I am going to upload. 10:08.400 --> 10:15.720 So you can see here we still have our yellow LCD, which is blinking, and if I put my hand closer to 10:15.720 --> 10:22.110 the end, it is blinking faster and faster and faster until I reach the point where you can see now 10:22.560 --> 10:27.250 the red and yellow are blinking at the same time. 10:27.270 --> 10:29.260 OK, I can do whatever I want. 10:29.520 --> 10:31.060 Now the application is locked. 10:31.140 --> 10:32.830 OK, there is nothing I can do. 10:33.630 --> 10:38.510 So the behavior for the yellow lady here has been replaced. 10:39.270 --> 10:42.290 So of course now we don't have the unlock mechanism. 10:42.300 --> 10:45.500 So if you want to just unlock, you have to restart the application. 10:45.750 --> 10:50.940 I'm going to press the reset button, which will stop the application from start from scratch. 10:51.450 --> 11:00.790 And now I can you can see I can move my hand and if I get closer, I will look at the application begin. 11:01.650 --> 11:07.680 So we have a nice warning, which means that, for example, your robot is going to close from a wall 11:07.680 --> 11:13.530 or an obstacle so you can, for example, stop the robot and then make the two entities blink. 11:13.860 --> 11:20.030 And as you can see, even if you remove the obstacle, even if the measure, the distance is no longer 11:20.030 --> 11:22.830 than before, the application is still locked. 11:23.310 --> 11:25.890 This is a mechanism that is quite useful. 11:26.220 --> 11:33.660 When there is some danger, you lock the application and then you ask for a human manual interaction 11:33.660 --> 11:37.820 with the circuit or the robot to unlock the application. 11:37.830 --> 11:44.490 So the user will need to first check and make sure everything is OK and then press on some button so 11:44.490 --> 11:47.520 the application can continue working as before.