1 00:00:00,820 --> 00:00:08,950 Hello, welcome back and a lesson we go going to see uninterrupted version of our interaction with drivers 2 00:00:08,950 --> 00:00:09,460 project. 3 00:00:09,910 --> 00:00:13,510 So I'm going to make a copy of this last project. 4 00:00:13,510 --> 00:00:15,420 We created number twenty five over here. 5 00:00:15,430 --> 00:00:18,580 I'm going to copy this and paste it over here. 6 00:00:19,150 --> 00:00:21,640 And I'll call this number twenty six. 7 00:00:24,440 --> 00:00:29,510 So what I'm going to do is I'm just going to add the word enwrapped, because I hear. 8 00:00:33,620 --> 00:00:37,190 It's copying and it's done copying expand this. 9 00:00:38,960 --> 00:00:42,860 We have sauce over here, whereas may not see over here. 10 00:00:43,780 --> 00:00:45,950 OK, so this is our old project. 11 00:00:45,950 --> 00:00:47,210 We had two tasks. 12 00:00:47,870 --> 00:00:52,700 We have we have the task that pulls the you out for new data and a one to one Condorcet. 13 00:00:53,300 --> 00:00:56,630 And we said I was a bit inefficient since we have to pull. 14 00:00:56,640 --> 00:01:03,110 Pull means checking, checking, always checking whether there's something new and requires spending 15 00:01:03,110 --> 00:01:04,840 processor cycles to do that. 16 00:01:05,450 --> 00:01:12,080 And we said a better a better architecture would be not to check just to go on and do your stuff. 17 00:01:12,500 --> 00:01:14,330 When there is new data, you'll be told. 18 00:01:14,810 --> 00:01:20,300 So you can think of this as having a mobile phone and you're always looking at a mobile phone. 19 00:01:21,280 --> 00:01:27,700 Because you think if you take your eyes off it and someone texts you, you wouldn't see the text, but 20 00:01:27,700 --> 00:01:32,770 then someone comes along and says, just go ahead, live your life and leave the mobile phone. 21 00:01:32,980 --> 00:01:38,750 When there is a new text message, you receive a tone that you would receive a sound and a vibration. 22 00:01:39,250 --> 00:01:44,500 So when there's a new text message that's like an interrupt, you can check a text message now rather 23 00:01:44,500 --> 00:01:49,780 than you keep your eyes on the phone, always looking, because what if someone sends a text and you 24 00:01:49,780 --> 00:01:51,940 don't see it uninterrupted the same way? 25 00:01:52,270 --> 00:01:54,790 So you can you can go ahead. 26 00:01:54,790 --> 00:01:57,410 You need not keep your eyes on the phone, OK? 27 00:01:57,580 --> 00:01:59,530 Anyway, I hope that's a fair analogy. 28 00:02:00,280 --> 00:02:09,330 OK, or in our previous projects we kept this here in our while in our main function while loop. 29 00:02:09,350 --> 00:02:10,990 This is not required. 30 00:02:11,110 --> 00:02:16,600 We forgot to clean this, but of course it has no effect here because the code doesn't reach whatever's 31 00:02:16,630 --> 00:02:17,020 in a while. 32 00:02:17,020 --> 00:02:22,950 Loop is not executed because once the Sketchley started, all of this is unreachable. 33 00:02:23,350 --> 00:02:28,480 But to keep it clean and tidy, I'm going to clean this and I'm going to go to the previous project 34 00:02:28,480 --> 00:02:29,450 as well and clean it. 35 00:02:30,190 --> 00:02:33,040 This one here interacting with you are two drivers. 36 00:02:33,370 --> 00:02:38,410 I'm going to open the immediate C4 and clean it. 37 00:02:41,600 --> 00:02:43,260 OK, I'll clean it from here. 38 00:02:44,420 --> 00:02:45,290 Control as. 39 00:02:46,590 --> 00:02:47,310 Close this. 40 00:02:49,110 --> 00:02:50,430 So this are new project. 41 00:02:50,820 --> 00:02:56,430 OK, so we said we wouldn't need polling, so I'm going to delete that task for polling. 42 00:02:56,850 --> 00:02:58,020 I'll delete this task. 43 00:02:58,890 --> 00:03:04,770 So we have just one task handle handle the handle the task, because I've deleted a polling task. 44 00:03:04,770 --> 00:03:09,720 I'm going to delete its task function from here as well and. 45 00:03:11,220 --> 00:03:13,680 The polling task, I'm going to delete it. 46 00:03:14,810 --> 00:03:16,040 From here as well. 47 00:03:17,120 --> 00:03:26,990 OK, so before we proceed, we have to initialise interrupt you currently our Ewart's IREX is not configured 48 00:03:26,990 --> 00:03:27,720 for interrupt. 49 00:03:28,160 --> 00:03:32,510 So we're going to write a piece of code that would configure it for interrupt. 50 00:03:33,710 --> 00:03:34,160 So. 51 00:03:36,450 --> 00:03:44,940 Or bring this block of code here, this code is called Starts, IREX interrupts, OK, and we're going 52 00:03:44,940 --> 00:03:49,920 to have a global variable that we call IREX interrupts in progress. 53 00:03:51,490 --> 00:03:56,440 Which I shall keep over here, I'll keep at the top over here, we have this global variable called 54 00:03:56,830 --> 00:03:58,240 IREX in progress. 55 00:03:58,270 --> 00:03:58,660 OK. 56 00:03:59,870 --> 00:04:07,360 Right, but what from a hardware perspective or were you at hardware perspective, we start Erich's 57 00:04:08,030 --> 00:04:14,180 by writing, by setting a particular bit in the control register, one too high, and this hexadecimal 58 00:04:14,180 --> 00:04:16,230 value corresponds to setting that bit. 59 00:04:16,640 --> 00:04:21,560 And again, if you want to learn how to write bedmate or drivers, there's a and have at least three 60 00:04:21,560 --> 00:04:22,690 courses just for that. 61 00:04:23,300 --> 00:04:25,100 So we just add this. 62 00:04:25,130 --> 00:04:29,090 This line here would enable interrupts mode for us. 63 00:04:29,420 --> 00:04:33,380 And once we've been able to interrupt mode, we have to set the interrupt priority. 64 00:04:34,330 --> 00:04:41,070 So this is different from our top priority, so we said it priority to priority of six in the Novik 65 00:04:41,380 --> 00:04:43,810 and then we are unable to interrupt to request. 66 00:04:44,950 --> 00:04:48,580 So the name of the incorrupt is used that to I arguin. 67 00:04:49,060 --> 00:04:50,350 OK, so that's it. 68 00:04:50,360 --> 00:04:52,940 That's the short explanation for this. 69 00:04:54,160 --> 00:04:56,460 So once we have this, we go ahead. 70 00:04:56,800 --> 00:05:02,410 And also I should point out that the interrupt, just like our. 71 00:05:04,600 --> 00:05:10,240 Just like our software time is interrupts how the callback function and what this means is. 72 00:05:11,270 --> 00:05:15,200 It has a function, though, to execute when that particular interrupts occurs. 73 00:05:16,680 --> 00:05:22,890 We saw in our software time is that we had to create Kobuk functions for them such that when there is 74 00:05:22,890 --> 00:05:26,400 a timeout, the content of the particular function will be executed. 75 00:05:26,820 --> 00:05:30,350 Is the same for interrupt interrupt require callback functions. 76 00:05:30,570 --> 00:05:33,540 In fact, that is the only way you make use of the interrupt. 77 00:05:34,270 --> 00:05:40,470 The point of the interrupt is that when something occurs, you want something, an action to be taken. 78 00:05:40,470 --> 00:05:44,610 That action that you want to be taken is placed in what we call the callback function. 79 00:05:45,090 --> 00:05:49,970 So we going to have a callback function and the callback function here. 80 00:05:50,010 --> 00:05:51,360 We don't just give it a name. 81 00:05:51,360 --> 00:05:56,670 The name is defined in something known as the vector or table, and you can find the vector table in 82 00:05:56,670 --> 00:06:02,180 the dots for the start up dots file of the project of every project. 83 00:06:02,400 --> 00:06:09,240 So the callback function of our user to as written as use out to underscore our cue handler. 84 00:06:09,840 --> 00:06:16,380 The callback function is also known as the IQ handler, and the reason for that is as the entraps request 85 00:06:16,380 --> 00:06:16,790 handler. 86 00:06:17,310 --> 00:06:24,180 So it's called either the interrupts callback function, the interrupt request handler or the interrupt 87 00:06:24,180 --> 00:06:25,010 service routine. 88 00:06:25,020 --> 00:06:28,280 You can also call it the guess are right. 89 00:06:28,290 --> 00:06:29,400 These are bedmate or. 90 00:06:31,230 --> 00:06:31,840 Concepts. 91 00:06:32,850 --> 00:06:39,750 OK, so there'll be a callback function here and what we place in this function is what we do is what 92 00:06:39,750 --> 00:06:43,190 we execute when uninterrupted chaos, OK? 93 00:06:43,770 --> 00:06:52,200 OK, so over here, this lesson is unique in that this the first time we are going to show you how to 94 00:06:52,860 --> 00:06:57,630 how we are going to show interaction between how to interrupt. 95 00:06:58,550 --> 00:07:08,120 And our our scheduler right over here, we have to declare a variable newnes higher priority task to 96 00:07:08,120 --> 00:07:15,930 be walking in free ARTUS whenever you enter and interrupt service routine or an interrupt request handler 97 00:07:16,010 --> 00:07:16,880 and you exit. 98 00:07:17,960 --> 00:07:24,560 You have the option to indicate whether you want a higher priority task to be woken up, so if we had 99 00:07:24,560 --> 00:07:32,030 multiple tasks in our system currently coming out of the incorrupt service routine, we can see that 100 00:07:32,360 --> 00:07:37,320 when you come out, wake up the highest priority task in the secular. 101 00:07:38,550 --> 00:07:41,100 This means don't go and continue where you left off. 102 00:07:41,130 --> 00:07:46,200 It could be that you were running a lower priority task before you entered the interrupt service routine. 103 00:07:47,080 --> 00:07:52,870 But we can see when you come out of the interrupt service routine, don't continue running your lower 104 00:07:52,870 --> 00:07:56,170 priority task, just wake up the highest priority task you have. 105 00:07:57,130 --> 00:07:57,550 Right. 106 00:07:57,870 --> 00:08:03,800 And the reason I'm saying come out is that you have to remember our process, all this one. 107 00:08:04,630 --> 00:08:10,480 So although we said we have a real time system and we're running in parallel, we run in multiple tasks 108 00:08:10,480 --> 00:08:11,270 in parallel. 109 00:08:11,410 --> 00:08:12,630 That is not quite true. 110 00:08:13,210 --> 00:08:20,920 What is happening is that each each task is given some time on the Processo and then after the time 111 00:08:21,070 --> 00:08:28,000 is exhausted, the task is taken off and a new one is brought very quickly, is so quick that we think 112 00:08:28,000 --> 00:08:29,460 it's all happening in parallel. 113 00:08:29,830 --> 00:08:34,870 So Wendy interrupts your case, the interrupt service routine, when the interrupt service routine is 114 00:08:34,870 --> 00:08:40,120 being executed, what would happen is that the process or will be given to the interrupt service routine. 115 00:08:40,420 --> 00:08:43,720 So the tasks in our scheduler wouldn't have any process or time. 116 00:08:44,140 --> 00:08:49,060 So it will be after our interrupt service routine has finished in the process so that you go back to 117 00:08:49,060 --> 00:08:53,740 our checklist tasks and then to continue so we would see how that would go. 118 00:08:54,560 --> 00:08:57,150 So we said, OK, we set in this to force. 119 00:08:57,190 --> 00:09:01,750 We start by declaring it and set it to force and then we go into. 120 00:09:03,720 --> 00:09:05,290 Check our status register. 121 00:09:05,370 --> 00:09:08,380 We're not Poulan, we simply checking our status register. 122 00:09:08,730 --> 00:09:14,480 OK, over here, you wouldn't find a while loop to wait for a character to. 123 00:09:14,540 --> 00:09:22,710 OK, so we say we simply say if status register sets, meaning if there is new data, then we want to 124 00:09:22,710 --> 00:09:27,960 take this story in a in a temporary variable like this. 125 00:09:28,800 --> 00:09:35,900 And then we would see if irex in progress over here, our ARITZ. 126 00:09:35,970 --> 00:09:42,040 If we see if IREX in progress, then we want to send this to the queue. 127 00:09:43,290 --> 00:09:47,730 The new data and this is the key part you see over here. 128 00:09:47,760 --> 00:09:56,670 I'm using the version of the function excuse and from ESR in Free Artus, you'd never use a function 129 00:09:56,670 --> 00:10:01,020 that hasn't got Isar at the end in the Isar. 130 00:10:01,650 --> 00:10:02,940 You have to keep this in mind. 131 00:10:04,110 --> 00:10:10,350 All functions, functions that we can function so we can use in Iosava, which means interrupt service 132 00:10:10,350 --> 00:10:10,830 routine. 133 00:10:11,460 --> 00:10:18,680 Daris, this is our version so we know we have our excuse function, our standard excuse in function. 134 00:10:19,110 --> 00:10:23,070 This is that the one that we are allowed to use and interrupt service routine. 135 00:10:23,400 --> 00:10:25,530 So is quote from ESR at the end. 136 00:10:26,460 --> 00:10:32,370 So over here, this is the handler of the Q we want to send to this is the value we want to send. 137 00:10:32,910 --> 00:10:40,020 And then over here we are indicating whether we want to we want to wake up a higher priority task or 138 00:10:40,020 --> 00:10:40,380 not. 139 00:10:41,810 --> 00:10:43,610 So over here, we are passing this very. 140 00:10:43,970 --> 00:10:49,910 We said it's a higher priority task walking we passing this year, we have to indicate that if we want 141 00:10:49,910 --> 00:10:57,440 to use this, we've started to focus, OK, once we are done over here after this, the data is going 142 00:10:57,440 --> 00:10:58,640 to be in our queue. 143 00:10:58,910 --> 00:10:59,320 Right. 144 00:10:59,600 --> 00:11:03,040 We have to use the process or we call the function. 145 00:11:03,070 --> 00:11:06,180 Porti yield from ISO Yudin means letting go. 146 00:11:06,200 --> 00:11:08,870 The process yield is like give up. 147 00:11:09,590 --> 00:11:10,040 Right? 148 00:11:10,230 --> 00:11:16,890 So we use the process or from Isar and we pass X higher priority task walking here as argument. 149 00:11:16,940 --> 00:11:17,390 OK. 150 00:11:19,530 --> 00:11:22,520 So I don't know if I explain this bit properly. 151 00:11:23,490 --> 00:11:25,150 The only confusing bit to be here. 152 00:11:25,200 --> 00:11:28,530 Over here we are saying don't wake up a higher priority task. 153 00:11:28,800 --> 00:11:31,590 Basically, that is why we have police force here. 154 00:11:31,830 --> 00:11:36,210 If we want to wake up a higher priority task, we can simply sit through here. 155 00:11:37,140 --> 00:11:44,310 But this the reason, uh, this is not quite relevant here is we have a single task here and it's got 156 00:11:44,310 --> 00:11:45,080 one priority. 157 00:11:45,450 --> 00:11:52,080 So over here we are saying, OK, when you come out of the interrupt service routine, if we had multiple 158 00:11:52,080 --> 00:11:59,570 tasks and one of them, one of them is blocked Wigdor one up and continue from the higher priority task. 159 00:11:59,820 --> 00:12:01,590 But over here, we are seeing force. 160 00:12:03,490 --> 00:12:12,160 Right, OK, so I think I may have spelt it differently, preforms is capital letters. 161 00:12:12,700 --> 00:12:16,360 OK, so we setting this to force. 162 00:12:17,140 --> 00:12:21,580 So actually I can simply pass false here and pass false here. 163 00:12:22,180 --> 00:12:27,430 So we have to indicate what form is or do we want to wake up a high priority task. 164 00:12:27,460 --> 00:12:28,540 We still say in force. 165 00:12:28,790 --> 00:12:30,480 OK, right. 166 00:12:31,240 --> 00:12:32,290 If you don't get this. 167 00:12:34,000 --> 00:12:35,410 Leave it in the question and answer this. 168 00:12:36,580 --> 00:12:41,500 We do not want to wake up from a higher priority task, although it makes no difference in this project 169 00:12:41,500 --> 00:12:42,820 because there's a single task. 170 00:12:42,970 --> 00:12:44,080 So we're looking good. 171 00:12:44,380 --> 00:12:48,190 No, we have to start to interrupt this function here. 172 00:12:49,380 --> 00:12:51,270 We have to call it somewhere. 173 00:12:53,070 --> 00:12:58,830 And also our you at our function, remember, in our previous project, we called it in our previous 174 00:12:58,830 --> 00:13:01,170 task, the pool Ewart's task. 175 00:13:02,890 --> 00:13:10,900 Because that task is no longer here, we will call that in our hands task, so our task first initialize 176 00:13:10,900 --> 00:13:15,940 the U at our X and then it would start the IREX interrupt. 177 00:13:16,570 --> 00:13:24,600 So overseeing our handler task will call these to you in initialised to you or use. 178 00:13:25,150 --> 00:13:31,990 And the reason why it is called USA is because the model is actually universal Synchronoss asynchronous 179 00:13:31,990 --> 00:13:37,780 receiver transmitter, but because we are using just the asynchronous bits we say you are not without. 180 00:13:37,810 --> 00:13:38,200 Yes. 181 00:13:38,210 --> 00:13:41,110 So I'm using the two words interchangeably. 182 00:13:42,040 --> 00:13:45,000 So we initialize the what's our X? 183 00:13:45,010 --> 00:13:50,440 And then we start IREX interrupt, OK, and there's nothing more to do here. 184 00:13:50,440 --> 00:13:56,200 We can just we need not put a function prototype out at all because this function is defined above this 185 00:13:56,200 --> 00:13:57,280 one that requires it. 186 00:13:57,890 --> 00:13:58,330 OK. 187 00:14:00,210 --> 00:14:01,940 So let's build and see what we've got. 188 00:14:03,830 --> 00:14:05,180 I'll click over here to build. 189 00:14:08,210 --> 00:14:09,230 We've got no notario. 190 00:14:10,480 --> 00:14:11,020 And. 191 00:14:12,420 --> 00:14:17,760 OK, I'm building the wrong one, it appears we're going to minimize this, this is our new one. 192 00:14:18,210 --> 00:14:19,800 Twenty six click to build. 193 00:14:21,570 --> 00:14:23,970 OK, we have a number of errors. 194 00:14:24,410 --> 00:14:25,990 OK, there's a difference in the spelling. 195 00:14:26,490 --> 00:14:27,900 I'm going to go to. 196 00:14:30,870 --> 00:14:35,540 Oh, are you to see fall over here and grab the function? 197 00:14:36,550 --> 00:14:40,180 This is how we split it here, I reckon it used to. 198 00:14:40,180 --> 00:14:41,350 You are in it. 199 00:14:41,500 --> 00:14:41,910 Okay. 200 00:14:43,980 --> 00:14:47,520 So this the spelling of the function, OK, let's click to build. 201 00:14:49,350 --> 00:14:52,050 No error, no warning, right, click. 202 00:14:53,320 --> 00:15:00,250 We're going to see debug us estimate 30 to double click number twenty six over here, I say, OK, over 203 00:15:00,250 --> 00:15:00,550 here. 204 00:15:04,160 --> 00:15:05,450 And then click to switch. 205 00:15:07,440 --> 00:15:09,570 And I'm going to open this. 206 00:15:10,640 --> 00:15:16,700 This is our realtor going to click to run and then going to press a key. 207 00:15:16,730 --> 00:15:22,970 I just pressed it on my keyboard with a cop's look on going to press capital D, capital B. 208 00:15:22,970 --> 00:15:23,840 Capital G. 209 00:15:23,840 --> 00:15:24,680 Capital T. 210 00:15:25,650 --> 00:15:33,810 And I'm going to press the number eight and then the number five and number six, OK, so it's working 211 00:15:33,810 --> 00:15:35,630 as expected, right? 212 00:15:35,730 --> 00:15:38,750 So this is how we can use enwrapped. 213 00:15:38,760 --> 00:15:45,510 Remember, the take away from this lesson is that if you want to use any function in the interrupt service 214 00:15:45,510 --> 00:15:50,770 routine, the particular free Arktos function has to end with from ESR. 215 00:15:51,390 --> 00:15:58,160 OK, and this here is used to indicate whether we want to wake up a higher priority task when the processor 216 00:15:58,170 --> 00:16:03,900 is given back to our scheduler, because when we are executing this hour hour to stretch, that hasn't 217 00:16:03,900 --> 00:16:04,460 got a process. 218 00:16:04,460 --> 00:16:07,530 So I will interrupt service fruitiness using it. 219 00:16:07,830 --> 00:16:08,670 When it's done. 220 00:16:08,680 --> 00:16:09,960 It would have to say, OK. 221 00:16:11,250 --> 00:16:17,640 We would have to decide whether we want to go to a higher priority task or we want to continue where 222 00:16:17,640 --> 00:16:20,390 we left off, even if that task had a lower priority. 223 00:16:20,700 --> 00:16:25,800 So that's what this parameter is for, is all there is for this lesson. 224 00:16:25,800 --> 00:16:26,710 And I'll see you later. 225 00:16:26,730 --> 00:16:27,510 Have a nice day.