1 00:00:02,350 --> 00:00:09,550 In this lesson we're going to demonstrate how to create an input capture firmware using the Cuban mix. 2 00:00:09,560 --> 00:00:15,410 For those of you who are not familiar with input capture input capture is used to capture the timestamp 3 00:00:15,740 --> 00:00:17,580 or final clearance of event. 4 00:00:17,690 --> 00:00:25,090 Let's say you want to capture the such time erase an edge or a fallen off a digital sensor or curse. 5 00:00:25,110 --> 00:00:32,770 Use inputs capture for such a case and I'm going to demonstrate how to quickly do input capture with 6 00:00:32,970 --> 00:00:34,670 timers using a Cuban mix. 7 00:00:34,670 --> 00:00:39,920 And if you want to learn more about input capture and then you want to you want further elaboration 8 00:00:40,040 --> 00:00:41,210 do send me a message. 9 00:00:41,210 --> 00:00:42,040 So let's kick off. 10 00:00:42,110 --> 00:00:48,230 Let's just use the the items provided on the Discovery board which is a button in the LCD to demonstrate 11 00:00:48,260 --> 00:00:49,510 this experiment as well. 12 00:00:49,670 --> 00:00:56,450 So I'll come to my Cuban mics and create a new project so I just minimize this and then I'll come over 13 00:00:56,450 --> 00:00:58,120 here for our new project. 14 00:00:58,130 --> 00:01:07,580 I have the f 4 and this is my microcontroller and what I want to do is I want to connect the push button 15 00:01:07,640 --> 00:01:15,410 of the discovery board to an input capture timer so that whenever I press that push button the the timestamp 16 00:01:15,410 --> 00:01:18,380 of the event is stored so you can. 17 00:01:18,380 --> 00:01:24,500 You can think of this as the exact time a particular event external event occurs. 18 00:01:24,500 --> 00:01:29,790 This is actually how we program things like ultrasonic sensor or in the case of the ultrasonic sensor. 19 00:01:29,900 --> 00:01:37,220 You want to detect exactly when the signal bounces back and it's detected and I have a tutorial of programming 20 00:01:37,250 --> 00:01:39,390 ultrasonic sensor on cortex. 21 00:01:39,410 --> 00:01:45,230 Dot com you can check that article out input capture is used to detect deal care and social events and 22 00:01:45,230 --> 00:01:49,670 it becomes very useful when you're doing signal processing and when you're doing things that require 23 00:01:49,670 --> 00:01:51,820 high accuracy and all of that. 24 00:01:51,900 --> 00:01:59,660 So moving on I've just Claire pains by clicking over here and what I want to do is connect my push button 25 00:01:59,690 --> 00:02:03,280 which is connected to key issue to a particular time. 26 00:02:03,320 --> 00:02:09,500 So I could just click here like this and I've got options to connect it to time to channel one or a 27 00:02:09,500 --> 00:02:11,310 time or five channel one. 28 00:02:11,570 --> 00:02:17,840 I'd just like the timer to turn a one over here and as you can see like I said when you see this orange 29 00:02:17,840 --> 00:02:21,000 color it means the configuration is incomplete. 30 00:02:21,050 --> 00:02:23,060 We have to complete somewhere else. 31 00:02:23,060 --> 00:02:29,680 So I have to go to timer two and continue the configuration. 32 00:02:29,820 --> 00:02:35,360 What I want to do is enable Channel 1 Cause this one is Channel One as an input capture direct mode 33 00:02:35,720 --> 00:02:41,370 like this so once that is done we need to come to the configuration tab over here and click on timer 34 00:02:41,390 --> 00:02:47,220 to to set a timer configuration and what we want is we want to set it time pre-schooler like we did 35 00:02:47,220 --> 00:02:52,230 in the other examples to the millisecond unit and to do that I'm going to put forty eight thousand here 36 00:02:53,300 --> 00:02:59,790 and once I do that I'm going to set the time count more as an up counter and account period I'm going 37 00:02:59,790 --> 00:03:06,600 to plan on enormous time contribution here meaning a one day time I count for five hundred seconds before 38 00:03:06,630 --> 00:03:07,460 it reloads. 39 00:03:07,470 --> 00:03:11,940 So this the size of my time just like a day has 24 hours. 40 00:03:11,940 --> 00:03:15,600 My time has five hundred five hundred seconds. 41 00:03:15,600 --> 00:03:19,680 So after 500 seconds the time I reset. 42 00:03:19,680 --> 00:03:25,740 So yeah once that's set we have to come over here for polarity set and do we want to detect a rising 43 00:03:25,830 --> 00:03:30,230 edge or the fallen edge of both edges of the signal. 44 00:03:30,240 --> 00:03:35,250 I choose the raisin edge here I mean as soon as I press the button it's going to be detected and I have 45 00:03:35,250 --> 00:03:41,160 to make sure the I see selection over here is direct and the pre-schooler division no division and I 46 00:03:41,160 --> 00:03:48,330 can add a low pass filter here with a value 10 the maximum value over here is you to 15 that's the maximum 47 00:03:48,330 --> 00:03:49,160 15. 48 00:03:49,400 --> 00:03:55,980 So then I have to set these parameters and yet so once this is done we move on to these other settings 49 00:03:56,070 --> 00:03:59,790 are going to erupt over here for a time or two so I'm just going to click here to enable. 50 00:03:59,880 --> 00:04:07,180 Once we've done that I think we can go ahead and generate our code I'll click over her give my project 51 00:04:07,180 --> 00:04:15,800 a name I call it input capture and then select my I.D. to call you vision 5 click Okay. 52 00:04:17,940 --> 00:04:21,030 Once that is done I open the project like this. 53 00:04:24,370 --> 00:04:30,000 And I can just expand and inspect and I'll just do it to bind everything. 54 00:04:33,080 --> 00:04:41,600 And it's done rebuilding and before I move on I'll just I want to just update my debug here to reset 55 00:04:41,660 --> 00:04:43,030 and run. 56 00:04:43,100 --> 00:04:45,850 Okay and then okay. 57 00:04:45,920 --> 00:04:52,250 So what I want is like like we did before in the other example we want to start the input copter timer 58 00:04:52,400 --> 00:04:54,370 and this time we want to start it. 59 00:04:54,380 --> 00:04:56,520 We interrupt not just start. 60 00:04:56,570 --> 00:05:02,000 So I'm just going to come over here to Main and I'm going to come to the function stop to look for the 61 00:05:02,060 --> 00:05:08,510 particular function for there and I'll just click the time I hear the timer module here to see the list 62 00:05:08,510 --> 00:05:14,220 of API stuff with a timer and this one here gives me the entire list. 63 00:05:14,450 --> 00:05:18,550 What I want is the timer inputs capture start which interrupts. 64 00:05:19,010 --> 00:05:26,060 So it's overhead time ISIS starts interrupt so I just click it to see it and then I just copy this and 65 00:05:26,060 --> 00:05:32,670 go and call this function in my main file or copy it like this. 66 00:05:32,660 --> 00:05:36,140 Then take it to mean then come over here. 67 00:05:36,170 --> 00:05:45,500 Then what I want to do is this is a pointer to my time a structure score. 68 00:05:45,840 --> 00:05:54,530 HDI and to us is defined upstairs here up here like this and the channel this China one. 69 00:05:54,700 --> 00:05:56,350 So I could just come over here. 70 00:05:57,900 --> 00:06:06,460 It's a time on the school channel 1 and then we've started the interrupt next where we have to do it. 71 00:06:06,480 --> 00:06:10,160 We have to declare the callback function for the interrupt. 72 00:06:10,290 --> 00:06:11,630 Meaning what code. 73 00:06:11,670 --> 00:06:16,140 What instructions do we want to run when the event occurs. 74 00:06:16,140 --> 00:06:22,110 So we have to create a callback function for this and then declare the piece of code in that function. 75 00:06:22,830 --> 00:06:30,700 Let's do that now so we can come back here and still look for the inputs capture callback whole. 76 00:06:32,260 --> 00:06:35,050 This is a hard time I cup to call back. 77 00:06:35,060 --> 00:06:38,900 We can just click over here and then copy it. 78 00:06:38,910 --> 00:06:40,290 This is how we treat callbacks. 79 00:06:40,290 --> 00:06:42,560 We copy it and then would declare the same. 80 00:06:42,570 --> 00:06:47,520 We write the same implementation without the weak object here. 81 00:06:47,610 --> 00:06:52,980 So I'm just going to copy this and take it to my main file and place it down here somewhere. 82 00:06:57,020 --> 00:07:01,090 Just put it over here and then delete the week for her. 83 00:07:01,250 --> 00:07:06,420 So in our callback function we can get the timestamp by using the whole time I get. 84 00:07:06,440 --> 00:07:15,010 Counter API and this one is basically on the score on the score or a timer. 85 00:07:15,120 --> 00:07:15,590 I am 86 00:07:19,130 --> 00:07:25,460 gets count to this one here like this and it takes time out and starts here as an argument which is 87 00:07:25,570 --> 00:07:29,450 H I T N H T I am sorry. 88 00:07:29,930 --> 00:07:35,690 This one here returns the young timestamp which is an integer or want to do is start a timestamp in 89 00:07:35,690 --> 00:07:36,170 a variable. 90 00:07:36,170 --> 00:07:39,560 So I'm going to declare a global variable here. 91 00:07:39,740 --> 00:07:47,090 I'm going to declare that you intend to follow it over you into that to underscore t volatile and I'll 92 00:07:47,090 --> 00:07:48,260 call this timestamp 93 00:07:53,230 --> 00:07:58,390 and what I'm going to do is I'm going to assign a timestamp going to start a return value in the timestamp 94 00:07:59,290 --> 00:08:01,240 just gonna see timestamp 95 00:08:04,590 --> 00:08:08,300 because this like this we are not quite complete. 96 00:08:08,300 --> 00:08:13,940 The problem with this callback function is the works with all timers as you can see from the name it 97 00:08:13,940 --> 00:08:20,180 didn't indicate what I'm using time or module one two three four five works with over time. 98 00:08:20,330 --> 00:08:27,290 So one other thing we have to do is we have to tell this function to verify if the if the event is occurring 99 00:08:27,350 --> 00:08:34,100 at the time or two and then if that is the case then gets the timestamp story to know variable to do 100 00:08:34,100 --> 00:08:43,790 that we can use a simple if clause if we know the time or instance if h t i m we're not a timer instance 101 00:08:44,010 --> 00:08:57,910 and then instance because time to do this now we get a timestamp we started timestamp here right. 102 00:08:57,940 --> 00:09:03,760 So anytime you press the button you would store the timestamp the timestamp basically is the time at 103 00:09:03,790 --> 00:09:09,340 which the events occurred or we might want to do also is to put a counter variable here and count any 104 00:09:09,360 --> 00:09:15,430 time we pressed a button should tell us which press that button was and then issued increment. 105 00:09:15,430 --> 00:09:21,230 So I can just pull you in 32 32 on the school put you in. 106 00:09:21,250 --> 00:09:27,500 To underscore t auto counter here. 107 00:09:27,500 --> 00:09:28,130 So this one. 108 00:09:28,130 --> 00:09:30,440 Tell us the number of times you press the button. 109 00:09:30,440 --> 00:09:36,800 Every time we press is just going to grant you increment this. 110 00:09:36,820 --> 00:09:39,230 So I have to put this in a block. 111 00:09:39,230 --> 00:09:39,490 Now 112 00:09:44,850 --> 00:09:46,560 then like this. 113 00:09:46,560 --> 00:09:48,950 So yeah our code looks complete. 114 00:09:48,960 --> 00:09:54,920 We compile when when we press the button the timestamp is going to be stored in this for Apple. 115 00:09:55,050 --> 00:09:57,770 This ball is going to store the number of count. 116 00:09:57,810 --> 00:10:00,710 Remember the time is going to be moving forward. 117 00:10:00,720 --> 00:10:03,270 Let's rebuild and test on our board. 118 00:10:03,420 --> 00:10:14,190 See I download onto my board and then I just run the debugger and what I want to do is pull my global 119 00:10:14,190 --> 00:10:20,480 variables in a watch window or right click over here at this to watch window one then to the counter 120 00:10:20,490 --> 00:10:22,940 variable to watch window one as well. 121 00:10:26,160 --> 00:10:28,460 Has to watch window one as well. 122 00:10:28,490 --> 00:10:41,130 I'm going to run the code let's see I'm going to disable hexadecimal few here the code is running and 123 00:10:41,130 --> 00:10:48,730 I'm going to press my button magic and see as I press the button this recorded a time which are pressed 124 00:10:48,730 --> 00:10:51,930 a button and then press the wires. 125 00:10:52,010 --> 00:10:53,660 So that time is still moving forward. 126 00:10:53,660 --> 00:10:54,710 Let's see. 127 00:10:54,710 --> 00:10:59,120 I'll press my button again and press twice this time. 128 00:10:59,130 --> 00:11:02,540 Remember the arrow of time moves forward. 129 00:11:02,540 --> 00:11:04,010 We are not resetting the time yet. 130 00:11:04,050 --> 00:11:05,530 Time is still moving forward. 131 00:11:05,550 --> 00:11:08,580 It's going to reload when it's reached. 132 00:11:08,580 --> 00:11:10,130 Five hundred seconds. 133 00:11:10,140 --> 00:11:12,330 Like we said we know what time my set is. 134 00:11:12,330 --> 00:11:14,100 So I'm going to press again. 135 00:11:14,430 --> 00:11:20,910 Press again I can press and you can see our low pass filter is work into. 136 00:11:20,940 --> 00:11:21,400 Yeah. 137 00:11:21,420 --> 00:11:23,940 There is no deep answer to this is good. 138 00:11:23,940 --> 00:11:30,660 So this is how we we create an input capture timer using a Cuban makes.