1 00:00:00,180 --> 00:00:00,670 Hello. 2 00:00:00,720 --> 00:00:01,170 Welcome back. 3 00:00:01,530 --> 00:00:08,700 So in this lesson like we said we are going to implement a war stick delay subroutines so I'm gonna 4 00:00:08,820 --> 00:00:12,290 create a function here called cystic weight. 5 00:00:12,780 --> 00:00:16,570 I'm given the word function and subroutine here interchangeably. 6 00:00:16,590 --> 00:00:25,680 Yeah it's called the cystic weight and first of all we um we go to the reload value. 7 00:00:28,470 --> 00:00:35,070 Um so what is going to happen is we going to subtract one from the content of the reload register. 8 00:00:35,070 --> 00:00:41,070 So we push we put our rate node value into our cystic reload register this a reload value we put into 9 00:00:41,070 --> 00:00:47,320 the reload register and we would keep subtracting one from this value until it reaches zero. 10 00:00:47,340 --> 00:00:49,350 That is where what time out would okay. 11 00:00:49,590 --> 00:00:52,740 And a unit here is Andy the clock cycles. 12 00:00:52,750 --> 00:00:55,310 And what I mean by this is um. 13 00:00:55,410 --> 00:00:56,430 Because we. 14 00:00:56,610 --> 00:00:56,820 Yeah. 15 00:00:58,820 --> 00:00:59,440 Okay. 16 00:00:59,460 --> 00:01:06,990 What I mean by clock psychosis my microcontroller its default clock frequency is 16 megahertz. 17 00:01:06,990 --> 00:01:12,790 And what this means is 16 million cycles. 18 00:01:13,950 --> 00:01:14,370 Okay. 19 00:01:14,370 --> 00:01:16,200 In one second. 20 00:01:16,200 --> 00:01:20,610 So it's execute 16 million cycles in one second. 21 00:01:20,620 --> 00:01:28,200 Does the meaning of 16 mega hit it simple to remember 80 megahertz means 80 million cycles executed 22 00:01:28,380 --> 00:01:35,450 in a single seconds it's like 80 million hits mega means million. 23 00:01:35,480 --> 00:01:39,110 So 80 mega hit equals 80 million hits. 24 00:01:39,500 --> 00:01:43,320 And this means 80 million cycles in a second. 25 00:01:43,340 --> 00:01:46,790 So my default frequency is 16 megahertz. 26 00:01:46,790 --> 00:01:54,370 In other words 16 million Hertz meaning 16 million psychos executed in a single second. 27 00:01:54,410 --> 00:02:00,470 So if we know 16 million cycles are executed in a single second. 28 00:02:00,470 --> 00:02:04,410 Then how long does it take to execute a single cycle. 29 00:02:04,430 --> 00:02:08,110 And this value is sixty two point five nanoseconds. 30 00:02:08,690 --> 00:02:15,090 So the unit here is sixty two point five nanoseconds which is equal to one cycle for this hour cystic 31 00:02:15,110 --> 00:02:17,750 wait subroutine that we right over here. 32 00:02:17,750 --> 00:02:20,050 So we're going to pass this argument. 33 00:02:20,210 --> 00:02:25,860 How how many cycles we want to delay for we're going to pass this argument to register our issue. 34 00:02:25,940 --> 00:02:33,050 So if I pass five I want to delay for five cycles which essentially equals five multiplied by sixty 35 00:02:33,050 --> 00:02:35,110 two point five nanoseconds. 36 00:02:35,150 --> 00:02:43,130 But yeah we would later only see how to have our delays in you know seconds in units such as seconds 37 00:02:43,220 --> 00:02:44,540 or milliseconds. 38 00:02:44,540 --> 00:02:47,150 So the argument is gonna pass into rage the RS zero. 39 00:02:47,180 --> 00:02:52,910 So by the time we get to the subroutine we are assuming we already have our zero which are what DeLay 40 00:02:52,910 --> 00:02:53,880 amount. 41 00:02:53,930 --> 00:03:01,720 What I'm gonna do now is get into the value that is in the system load or the system reload register 42 00:03:02,180 --> 00:03:08,330 so to invoke s t reload underscore Ah over here 43 00:03:15,190 --> 00:03:26,490 and then I'm simply going to subtract one or two sub one from our zero hour zero. 44 00:03:26,560 --> 00:03:34,270 So what DeLay amount and then I'm going to start a new value after I perform the subtraction what is 45 00:03:34,270 --> 00:03:39,400 left I'm going to store it. 46 00:03:39,400 --> 00:03:45,840 So after I perform this subtraction I'm going to start a resort in the reload register by using the 47 00:03:45,840 --> 00:03:49,720 store instruction and then our zero hour one over here. 48 00:03:52,250 --> 00:03:52,540 Okay. 49 00:03:52,540 --> 00:03:57,220 So once that is done I'm gonna do load R 1 50 00:04:00,030 --> 00:04:07,960 because and fake cystic control register underscore Ah right. 51 00:04:08,210 --> 00:04:11,860 And what I'm gonna do next is load. 52 00:04:11,860 --> 00:04:13,500 I'll use a different register. 53 00:04:13,970 --> 00:04:27,000 Our three are one over here and then I'm going to check whether our count flag is set or 2 and s and 54 00:04:27,580 --> 00:04:36,080 then are 3 0 3 0 3 or 3 and then we created a symbolic name for the count. 55 00:04:36,700 --> 00:04:45,970 This one here to perform on an operation of the content of our three course um off the content of our 56 00:04:45,970 --> 00:04:46,360 three. 57 00:04:47,480 --> 00:04:52,670 There's a mistake here of the contents of our three with the count flag. 58 00:04:52,780 --> 00:04:58,270 Remember our three would have what is located in the register. 59 00:04:58,270 --> 00:05:03,910 This is the control register we've put in our three and we're doing what is in our three and it on end 60 00:05:03,970 --> 00:05:08,800 operation and then we start a resort back into R3 I'm using three options here is the same as using 61 00:05:08,800 --> 00:05:10,240 two appearance it's fine. 62 00:05:10,270 --> 00:05:12,040 It should work the same way. 63 00:05:12,310 --> 00:05:14,110 Right. 64 00:05:14,110 --> 00:05:18,250 Once that is done we want to check if the count flag is set. 65 00:05:18,250 --> 00:05:25,910 If it is not set we'll branch to lessee or create a loop RC LP one here. 66 00:05:26,050 --> 00:05:29,180 We keep checking if they can't flag is no set. 67 00:05:29,440 --> 00:05:31,160 Come over here. 68 00:05:31,450 --> 00:05:31,780 Right. 69 00:05:32,050 --> 00:05:37,080 And the reason we are using b q is when we perform the N operation we append it s over here. 70 00:05:37,120 --> 00:05:48,340 Whenever you see me or whenever you see on instructions such as move s or sub S O at s in fact whenever 71 00:05:48,340 --> 00:05:54,280 you see an instruction which s it means you want to update the AP s r registers when you perform that 72 00:05:54,280 --> 00:06:01,000 particular instruction and the EPA s registered s um the you want to update the AP flags. 73 00:06:01,690 --> 00:06:08,350 Yes some flags in the AP s I registered I get updated based on the results of a particular um execution. 74 00:06:08,560 --> 00:06:09,970 So we have the Zero flag. 75 00:06:10,000 --> 00:06:14,130 We have the overflow flag we have the carry flag we up the negative flag. 76 00:06:14,230 --> 00:06:19,270 This shows you um that the last operation that you performed returned a negative value that last we 77 00:06:19,260 --> 00:06:21,460 appreciate that you performed a return to zero. 78 00:06:22,540 --> 00:06:28,990 So that is why we appended it here so it just checks whether after our subtraction the um the answer 79 00:06:28,990 --> 00:06:29,950 is zero. 80 00:06:29,950 --> 00:06:33,460 If it is not we come back to the top over here. 81 00:06:35,560 --> 00:06:37,330 Um this checks. 82 00:06:37,360 --> 00:06:37,950 Um what uh. 83 00:06:37,980 --> 00:06:44,240 After our N operation I should say course with the form and an and over here. 84 00:06:44,590 --> 00:06:49,810 So we keep returning to the top here until the flag is set right. 85 00:06:49,810 --> 00:06:51,860 The current flag is set. 86 00:06:52,240 --> 00:06:52,910 Okay. 87 00:06:52,960 --> 00:07:00,940 So once that is done we can return from the subroutine bookseller like this. 88 00:07:01,510 --> 00:07:01,810 Okay. 89 00:07:01,840 --> 00:07:04,000 So this is our a cystic wait subroutine. 90 00:07:04,000 --> 00:07:11,130 No we gonna create another the subroutine to um to um to allow us to be able to delay in this a milliseconds. 91 00:07:11,140 --> 00:07:19,210 We going to create 10 milliseconds delay such that we gonna make such that when you call the subroutine 92 00:07:19,270 --> 00:07:24,320 it's gonna delay for 10 millisecond if you pass on documents of one and if you pass on arguments of 93 00:07:24,340 --> 00:07:30,880 hundred it's going to delay hundred multiply by ten EMIs which is equal to one second something of that 94 00:07:30,880 --> 00:07:32,660 nature. 95 00:07:32,980 --> 00:07:45,530 So I'm gonna come over here to create a new subroutine call this I call this mistake wait 10 EMIs and 96 00:07:45,530 --> 00:07:47,560 then I'm gonna take the argument. 97 00:07:47,600 --> 00:07:50,090 So we're going to pass our dollar amount into register. 98 00:07:50,130 --> 00:07:53,900 Iris 0 so I'm gonna move it from our 4 0. 99 00:07:53,910 --> 00:07:57,020 I'm gonna move it into our four or do move s.. 100 00:07:57,500 --> 00:08:03,200 And as you can see I've added as to this operation because I need the EPA as our flux to update on this 101 00:08:03,990 --> 00:08:04,710 move. 102 00:08:04,760 --> 00:08:07,290 What is in our zero into our four. 103 00:08:07,550 --> 00:08:18,590 And I'm going to say BQ if if after this operation if if the um if the argument is zero then branch 104 00:08:18,590 --> 00:08:20,640 to a place that I'm going to name. 105 00:08:20,740 --> 00:08:21,490 Done. 106 00:08:21,520 --> 00:08:23,690 Meaning if you pass zero for the dollar amount. 107 00:08:23,720 --> 00:08:28,430 There is no need to execute anything the subroutine should simply return. 108 00:08:28,430 --> 00:08:30,870 So I'm gonna put a label here underscore underscore. 109 00:08:30,890 --> 00:08:31,830 Done. 110 00:08:32,300 --> 00:08:43,240 And this simply going to return from the subroutine be set low so low over here right. 111 00:08:43,260 --> 00:08:44,410 Okay. 112 00:08:44,710 --> 00:08:50,080 So if this is not a case then I'm going to um I'm gonna perform the actual delay 113 00:08:53,020 --> 00:08:56,920 so I'm gonna create uh constants somewhere. 114 00:08:59,080 --> 00:09:05,400 Um I'll put it up here or create delay. 115 00:09:07,000 --> 00:09:09,900 Let's see 10. 116 00:09:11,050 --> 00:09:12,550 Call this 10 image delay. 117 00:09:12,550 --> 00:09:13,200 How about this. 118 00:09:14,740 --> 00:09:19,060 And then I'm gonna assign the number this is based on my clock frequency. 119 00:09:19,170 --> 00:09:19,690 You call you. 120 00:09:19,690 --> 00:09:21,820 I'm gonna give 160 thousand 121 00:09:25,190 --> 00:09:28,610 I'm gonna give 160 thousand. 122 00:09:28,610 --> 00:09:28,990 Right. 123 00:09:29,150 --> 00:09:33,240 So that's the explanation for the one sixty thousand we have here. 124 00:09:33,500 --> 00:09:34,150 Right. 125 00:09:34,160 --> 00:09:43,010 Like I mentioned earlier 16 million equals one hurts my microcontroller is running at sixteen megahertz 126 00:09:43,070 --> 00:09:50,810 meaning sixteen million cycles in a second and in another way of expressing this as 16 million equals 127 00:09:50,810 --> 00:09:57,420 one hertz and we know a thousand milliseconds equals one hertz as well. 128 00:09:58,100 --> 00:10:00,740 Then we want to create 10 seconds we want to find. 129 00:10:00,740 --> 00:10:05,110 How many how many cycles do we get with 10 milliseconds then. 130 00:10:05,120 --> 00:10:07,850 Cause we say we create in 10 milliseconds. 131 00:10:08,030 --> 00:10:16,400 Well for 10 we do want 10 divided by 1000 10 milliseconds divided by 1000 milliseconds times 1 hertz 132 00:10:16,700 --> 00:10:26,910 which equals one over 100 to see how many psychos we get for one over 100 heads. 133 00:10:27,020 --> 00:10:30,010 We simply more to play one over one hundred times. 134 00:10:30,020 --> 00:10:36,760 I was 16 million or sixty million cycles which is equal to one hertz and then we get one sixty thousand 135 00:10:36,980 --> 00:10:44,300 to this um this perhaps I don't know if any of you could explain this in a simpler way but yeah I'm 136 00:10:44,300 --> 00:10:49,730 sure there are simple explanations out there and then you can share it in the comment area if you can 137 00:10:49,730 --> 00:10:52,140 explain this to your fellow students in a simpler way. 138 00:10:52,160 --> 00:11:01,050 So basically um 16 million cycles of course one hertz and this equals one hundred m is it. 139 00:11:01,170 --> 00:11:08,690 Uh this was a thousand M S so then the question is we want a hundred m s equivalent in psychos. 140 00:11:08,810 --> 00:11:16,220 And one could say you are you can't so two zeros here you can't so two zeros here you are left with 141 00:11:16,270 --> 00:11:22,470 160 thousand cycles has the this constant is 160 thousand right. 142 00:11:22,620 --> 00:11:22,980 You know what. 143 00:11:22,980 --> 00:11:23,950 Continuing. 144 00:11:24,170 --> 00:11:24,470 Right. 145 00:11:24,470 --> 00:11:25,930 So we've created a constant. 146 00:11:26,060 --> 00:11:29,110 Let's continue to create a 10 m s delay. 147 00:11:29,970 --> 00:11:38,390 Um so we said f 0 is past this argument the D subroutine is going to return if that's not the case then 148 00:11:38,390 --> 00:11:44,510 we're going to subtract we're gonna subtract something from a while constant or delay amounts when a 149 00:11:44,510 --> 00:11:46,970 load or what delay amounts here. 150 00:11:50,110 --> 00:11:51,920 I'm going to load. 151 00:11:52,090 --> 00:12:03,730 I'm going to use RC reload r 0 with our delay amount which is this our 10 m s and then I'm gonna call 152 00:12:03,730 --> 00:12:04,720 our cystic wait 153 00:12:09,470 --> 00:12:14,250 be a cystic reach over here. 154 00:12:15,270 --> 00:12:15,710 Right. 155 00:12:15,720 --> 00:12:22,440 And then once cystic weight has done it s thin once you know it's returned I'm going to subtract one 156 00:12:22,440 --> 00:12:32,670 from our daily amount by doing the sub as sub subs as UBS and then remember our phone still has a copy 157 00:12:32,670 --> 00:12:33,500 of the argument. 158 00:12:33,510 --> 00:12:39,060 What the uh the argument we passed cause the argument is are it's a no show but we copied it into our 159 00:12:39,060 --> 00:12:39,570 four. 160 00:12:39,610 --> 00:12:41,220 So we still have the original argument. 161 00:12:41,210 --> 00:12:42,050 Yeah we reused. 162 00:12:42,060 --> 00:12:49,080 We used our sue later on for our 10 m s constant so our 4 has the argument we passed initially. 163 00:12:49,100 --> 00:12:49,820 No. 164 00:12:49,890 --> 00:12:55,890 So we say our four our four minus one. 165 00:12:55,890 --> 00:13:03,080 And then we are going to subtract one and if we subtract and it s not equal to zero. 166 00:13:03,090 --> 00:13:06,250 If the result is not zero we are going to branch. 167 00:13:06,290 --> 00:13:09,900 If it's higher we're going to branch. 168 00:13:09,930 --> 00:13:15,600 If the resorts in our fall is higher than zero I'm gonna use P H I instruction here and then I'm gonna 169 00:13:15,720 --> 00:13:20,610 branch to the spot LP 2 and I'm going to put LP 2 here. 170 00:13:20,610 --> 00:13:22,410 Right. 171 00:13:22,620 --> 00:13:24,440 So this is it. 172 00:13:25,290 --> 00:13:26,510 I think yeah it looks good. 173 00:13:26,520 --> 00:13:26,880 No. 174 00:13:29,370 --> 00:13:30,000 Okay. 175 00:13:30,060 --> 00:13:36,000 So we can a line and and there s the loss of 15 176 00:13:40,430 --> 00:13:40,930 right. 177 00:13:42,870 --> 00:13:43,420 Okay. 178 00:13:43,840 --> 00:13:44,120 Okay. 179 00:13:44,140 --> 00:13:47,490 So now let's test our program. 180 00:13:47,500 --> 00:13:56,070 I'm gonna create two new subroutines here for LGB on an LCD of when I have a lady own. 181 00:13:56,560 --> 00:13:59,310 And this is simply going to turn on the red LCD. 182 00:13:59,860 --> 00:14:08,260 I'm gonna do load R one and then GPL you f data register 183 00:14:11,600 --> 00:14:13,570 and then move into our 0 184 00:14:16,840 --> 00:14:29,830 the lady read and then store our as you are 1 and then be SLR return from subroutine. 185 00:14:29,840 --> 00:14:33,820 Now we're gonna have a lady of 186 00:14:37,900 --> 00:14:41,710 and then this is implemented the same way. 187 00:14:41,710 --> 00:14:55,750 Load our 1 GPL you f data register move into our 0 this time read off 188 00:14:59,740 --> 00:15:06,360 and then store our 0 are 1 and then be slr. 189 00:15:10,070 --> 00:15:10,430 Okay. 190 00:15:10,730 --> 00:15:13,010 So now in our main loop over here 191 00:15:16,520 --> 00:15:22,770 um we can um we can test out our code. 192 00:15:23,120 --> 00:15:25,610 I'm gonna come over here and load our 0 193 00:15:28,480 --> 00:15:33,650 A C or load our show across our storage the register. 194 00:15:33,670 --> 00:15:36,240 Doc likes the arguments of our subroutine. 195 00:15:36,240 --> 00:15:37,880 I'm going to load it with the number. 196 00:15:38,630 --> 00:15:47,250 But this one hundred and then I'm gonna do a two hour wait 10 m s 197 00:15:51,880 --> 00:16:04,480 and then I'm gonna call the lady on bill on a score a lady on and then I'm gonna load our issue again 198 00:16:06,360 --> 00:16:12,820 with one hundred so one hundred multiply by ten m s of course a thousand m s of course one second and 199 00:16:12,820 --> 00:16:13,780 I'm going to be able 200 00:16:17,320 --> 00:16:29,830 to wait to m s and then be L and a score early d off right and I'm going to keep this in a loop and 201 00:16:29,830 --> 00:16:31,960 I'll put a loop here. 202 00:16:32,530 --> 00:16:33,200 Right. 203 00:16:33,250 --> 00:16:35,920 We're looking good. 204 00:16:35,920 --> 00:16:42,230 Okay so we can try out all code see what we have. 205 00:16:42,330 --> 00:16:44,620 Gonna click here to build 206 00:16:47,780 --> 00:16:50,590 this picture that Roy says but register symbol 207 00:17:09,410 --> 00:17:11,240 probably have a partridge somewhere. 208 00:17:15,240 --> 00:17:18,690 Okay this first type will we get to build 209 00:17:23,790 --> 00:17:24,990 look at that. 210 00:17:25,160 --> 00:17:29,910 I was supposed to write a line that I ended up typing and 211 00:17:35,090 --> 00:17:39,880 Turbo the Okay we've got two more. 212 00:17:41,040 --> 00:17:41,470 So. 213 00:17:41,480 --> 00:17:41,820 Whoa. 214 00:17:43,710 --> 00:17:44,370 Yeah. 215 00:17:44,410 --> 00:17:45,950 They shall use using the load. 216 00:17:45,960 --> 00:17:47,650 You don't use this. 217 00:17:47,760 --> 00:17:49,860 This is how to load. 218 00:17:49,860 --> 00:17:50,850 We could have done move. 219 00:17:53,280 --> 00:17:56,980 Okay so there's a typo with regards to this. 220 00:17:57,300 --> 00:18:01,210 And Vic is the current register are over here. 221 00:18:04,750 --> 00:18:15,070 Okay let's set our target options debugger I'm using these the libraries I CDI come over here reset 222 00:18:15,070 --> 00:18:15,550 and run. 223 00:18:15,790 --> 00:18:16,380 Okay. 224 00:18:16,380 --> 00:18:16,680 And then. 225 00:18:16,750 --> 00:18:17,200 Okay. 226 00:18:20,380 --> 00:18:28,480 So I'm gonna quicker to download onto my board to download in my early days. 227 00:18:28,480 --> 00:18:29,140 Not Blinken. 228 00:18:29,350 --> 00:18:32,290 Let's see. 229 00:18:32,440 --> 00:18:33,910 Right. 230 00:18:34,240 --> 00:18:34,630 Right. 231 00:18:34,630 --> 00:18:39,460 The reason we have in this issue is we need to push. 232 00:18:39,610 --> 00:18:43,150 Register our 4 and L 4 We need to save them. 233 00:18:44,360 --> 00:18:46,870 Um yeah. 234 00:18:48,030 --> 00:18:49,210 I'm gonna push 235 00:18:58,090 --> 00:19:00,530 our file and a link register 236 00:19:05,150 --> 00:19:09,600 and then before I return from the subroutine I'm gonna pop them pop 237 00:19:12,500 --> 00:19:15,590 R for and then the link register. 238 00:19:16,500 --> 00:19:22,640 Okay let's build and see if this solves so what is you gonna click here to build. 239 00:19:28,170 --> 00:19:31,020 I'm going to click here to download onto the board. 240 00:19:31,510 --> 00:19:34,160 S can see my LCD is blinking. 241 00:19:34,290 --> 00:19:36,260 So this brings us to the end of this lesson. 242 00:19:36,260 --> 00:19:39,780 If you have any questions at all just let me know and I'll see you later. 243 00:19:39,780 --> 00:19:40,570 Have a nice day.