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Hello fellas.

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Welcome back.

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So in this very lesson we agreed to write code for the third most common use of timers which is measuring

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the time between events and we're going to use this to program an ultrasonic stencil.

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We're going to take the sensor and write it at drivers for it using what we've learned from timers.

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And then we're going to test it out.

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We're going to output the distance an obstacle in front of the ultrasonic sense or centimeters.

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So let's get on with it.

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We've seen that theory.

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If you did not understand that bit don't worry we are going to write the actual code here.

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And once again if there is still something you do not understand please live it in the comments section

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or just send me a message.

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So I have created a new forward or already calling this particular for the measuring time between event

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and I've created a new project inside this folder and I'm calling this project or trust on essential.

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I've done all of this just to shorten the the length of the video so I'll wait for you to do that once

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you're done.

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You come here the social group you rename it to the name of the microcontroller and then you said this

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side to the target is Tim 4C One two three and then the source group is the court just one resource

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group one folder created which is the application for that.

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Then you come here.

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You set your target options you change X to 16 and then your debugger you drop down here select still

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areas a CDI and don't forget to take this right.

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That being said let's create our main dot see far right click at new item that see and then the main

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is the name of the file.

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So.

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So yes let's crack on.

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We start by adding the head of file or file microcontroller by right click in and select in this and

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then to improve readability or to increase readability we can just start by using symbolic names.

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Remember we have four pillars for our ultrasonic module.

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It's called The Echo pin.

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The trigger pin the FEC and the G and D the echo and trigger pins digital pins that we have to use and

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we are going to connect the echo pin to P P 6 and we are going to connect the trigger pin to be for.

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So we define it as a symbolic names like this and then we're going to use the blue D just to create

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some output to less as defined a plurality as well.

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And there we have it.

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Long let's open our main function into me

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and let's just keep it open.

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No we need to create a couple of functions we need to create actually for individual functions you have

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to create one function to initialize the timer that we're going to use for detecting the edges in order

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to measure the time between the the edges we're going to create another function to create a microsecond

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delay for us and then we're going to fact to go in and create another function to initialize outputs

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rather than initialize and in the main this time let's just create a new function for Port initialization

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and we're going to create the final function to calculate to measure and calculate the distance of the

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object in front of the truss on except so let's start with the first function the time must zero in

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that we're going to use time as 0 for the arm for the the edge capture we're gonna use two timers like

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we said in the previous lesson the first time will be used to detect the urges in order to measure the

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time between them.

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So we're going to use timers here of this for this and I'm calling this function time as you were in

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it.

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So we start by by providing them with the access to clock and then that time a series is going to be

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used with the Echo pin you want to detect how long it takes the signal to return to the Echo pin we

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want to detect when the equipping tens Hi.

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So just to recap on what we supposed to do with the code we going to write the code to perform this

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for us first before we set it off the ultra sonic module Hi wait for this signal to bounce back to the

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echo we started timer when the Echo is detected and then when we stopped the time or when the echo goes

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slow so this timer is the time of zero that we write in.

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And so as we've defined above here the echo spin is connected to p B6 in order to detect the signal

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changes are p B6 we need to use time of zero cause P B6 is connected to time as you are right.

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So what we want to do like we saw in the theoretical part of the lesson is to start a timer when PBS

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6 goes high and then stop the timer when P B6 goes low cost P B6 is the echo spin if you're forgotten

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or are a bit confused just go to the previous listen and see how we initialize the the ultra sonic central

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drivers but this the code and leave your questions below.

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If you have any show we activate the clock for time on module 0 right and then we would provide clock

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access to port B since P B6 is on point B after this we set p B6 we set previous which is the echo pin

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us inputs begin by writing this to the direction register and then we digitally enable the echo pin

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like this next will be to set the P C T O and the upscale the alternate function select to register

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which we have to enable for the Echo pin because we're using the alternate function of P B6 after we

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enable the alternate function we have to set the p CTO and we set it this way is a two step approach.

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First right this particular hexadecimal code into the register and then write this.

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Remember there is a table that tells us what to write and we treated this the previous lesson and it's

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also available in the data sheet.

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This code overhead.

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Now let's go ahead to program the time a module 0 itself.

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So as we said before you couldn't figure out a time might you have to first disable it and would do

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this by accessing the control register.

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And this this is a new way of showing you how to disable using this on this unsigned over here and until

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the sets bit sets the first bit disabled is the same as type in equal to zero x zero.

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Right.

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But this is a friendly way of disabling it.

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This one disables just the first bit whereas this disables or bits in the register.

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So after that we go to the time a serial configuration register and then set it to 16 bits mode.

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We know this already we've been dealing with this in the other examples to set it to 16 bits mode.

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You just have to write for into this.

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You have to register and we know why that is.

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We can verify from the data sheet and this form is the same as X.

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So for like this the next thing will be to go to the timer a mode register and with the mode register

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we said we are setting characteristics of the timer.

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We enable it as an edge time mode capture mode and an up counter.

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That's why we have this hexadecimal code 2 x 1 7.

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If you expand it this is what it is in binary and these two bits enables us a capture mode and then

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this one bit.

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This one here it's number two here enables it as an edge time mode and then bit over here sets as an

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upper contact this one sets it as an up counter.

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In fact we can verify this from the data sheet.

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I'm gonna go to the data sheets and just show you how I came up with this code how I derive this.

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So we could just open a data sheet to help mine here it's just a portion of it.

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So you can just type and such.

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Keep team Cabinet papers timer TMR here like we did when compute your credit you'd realize over here.

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So this is it.

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We use the first two bits and let's see where the first two bit does two in one voice bit two in one

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useful bits you're in one it's defined us.

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This is it it's known as the T.

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And our values are defined this way.

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This the value in that description if you set it to 0 x 3.

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It's a capture mode and 0 x3 is 1 1 Cimino.

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So the first 2 one sets it to the capture mode.

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And then let's see the M with us the bits.

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Number two the course this is bit 0 1 but to be 2 Let's see what the data sheet says about bits 2 over

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here we should have been to number two is the capture mode so we set a too if we said the value one

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is each time mode and that is why it's to set one course we wanted to get the edge time not edge count

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so Beta 2 set to 1 and is the same today and our register has two sets one.

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Now let's see bits to number four what is.

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Number four two bits.

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Number four is the current direction.

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And it says when you set it to one the timer count up when counting up the time I started from fighting

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off to 0 hands.

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We have these by these.

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That's why we have this here.

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Each time mode capture mode up counter and this what it means.

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I hope you understand.

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Yes that's how it is derived.

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So the next thing we have to do is to access the time I could register again and set more of the parameters

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we require.

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And this is it the time control register gives us the ability to set where we want to detect rise in

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age only fall in error on the or both edges and then to set it for both ages you have to change the

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timer eight events bit to 1 1 and this is fine in this register.

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So just to do it for you and show you how it's derived a school to the data sheet and see what happens

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when we set this bit to 1 1.

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So I'm just going to go to the data sheet here.

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I'll just search comeback here like this and now enter.

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And this The Register we're looking for and

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what.

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Which bits are we looking for.

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We just checked out again.

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OK we're looking for the first four bits.

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Right

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so the first full bit the first bit is use to enable it rights.

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The second bit is used to set a stall in this one.

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It's two and three I use for the event.

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So let's see it's two and three it's 2 3 2 3.

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Here is it and distant description assess says when you set to see you X you you want to detect positive

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edge which is res image.

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We said to two X one you wanted to take the negative x mean and the fallen edge where you said to zero

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x to me you want to detect both edges.

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So when you compare this to x 3 where you converted and it's position you end up with a code 0 x 0 c

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we convert to x 3 and I put this code cause this 2 x 3 is not at the beginning right.

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Because this you X to me is the fourth.

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Let's see it's the third and second bits of this register.

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So if you're serious you in fact when you do the calculation you see it like it did.

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I explained it to her form is what it looks like right.

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This is why we have zero XY.

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And if you combat this binary code to hexadecimal you will get this.

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Finally what we have to do is to enable the timer by access in the quantum register then looks.

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So this is all the risk for the time I see your initialization function with initialize it with these

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parameters.

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The next thing would be to write a delay function to provide us with a microsecond delay.

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So that's what we are going to do next.

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So the lesson is getting a bit long.

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So let's continue the next lesson.

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See you.