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So now let's start to write out our code.

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I'm going to delete this line here.

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It's not needed.

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It was for your reference only.

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And we're going to stop by right now.

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Our directives remember the directives they help the Compiler Compiler the code in a particular way.

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We're going to start by hitting four tops.

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One two three four.

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And I will start with a first directive shall be written in Cobb's area and then tab vertical line dot.

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And this directive here makes our code callable from a C code a code written in C and we add the other

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directive C or D is tells the compiler to place the following line in the code space which is usually

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the wrong comma.

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Let's just make it read only safe this way unless our line line it of to.

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Now we could tell the compiler that our code is written in thumb to empty thumb.

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And then we export our program and export our program

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and we're going to call Let's call our program made.

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So we export main you know what the export directive does.

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It makes this program of this program callable from other other programs.

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So this file the content of this file can be caught from other files.

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You know the dot text makes it callable to see files by export makes it callable to assembly files and

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see files and it takes would not work without the export main.

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So now our program is made.

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So we export in Maine.

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So now let's write out our program.

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We start by in Maine the first and we're going to do is initialize our pot and pen and we're going to

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do this by writing a subroutine to do that for us.

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And remember there to be L is branch 2 subroutine I'm going to use the P L up code to do this and we're

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going to call this first subroutine G P i o f in it as the name implies it's going to initialize the

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general purpose input output to put s KPI in it.

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And remember we want to turn on the red LCD and we realized when we checked into data sheets that it

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read LCD is connected to put f pin 1.

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So that's the one we have to initialize for our initialization.

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We are going to use something known as index an immediate addressing index addressing uses two or requires

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two registers one register points to a value and the value pointed to by this first register is then

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put into the second register and we do these two steps by using the L T R to load up code image ID address

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in uses the move up code to move the value into a register.

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So first as we said we have to activate the clock of the pot s here.

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Does the first and we have to do it and it said set number three we have to set it direction registers

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and then enable.

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Remember we're not doing this one here cos we're not using PD 7.

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So what we are going to do now is write out the content of our subroutine our subcutaneous code.

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Keep you f in it.

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So what we're going to do is load load the address of the clock into register 1 and we do this call

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in the r r one because system control our CDC keeping who on a school r remember addresses 32 bit large

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numbers here.

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Load R1 ecosystem control RC TCE TPA or R is pointing to the address I should tell you the name here

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system control RC KC TPA or R is a name you could think of it as a name was given to the numeric value

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of the address.

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Later on we would see how we assign this name to the 32 bits number before now now keep this name and

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now explain to you why we use in this long name which underscores rather than getting a simple name

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that we can remember.

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So let's move on now.

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We have our one pointing to the address of the system control register which is the clock register.

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Now we have to take the content at this address and put it into our cereal and we do that by invoking

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l the r r zero comma square brackets are 1.

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So now the content at this address pointed to by R1 is put into our zero.

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If you go back to the data sheet you would realize that they reset value of their system control our

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C GC GPI register as 0 0 0 0 0 with a series after the X currently.

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I'll tell you this value is put into our cereal so our cereal currently has this value in order to enable

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put F..

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We will have to enable bit 5 in the system control our CTC keep register and we can accomplish this

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by using something known as the or operator like this all power are our zero equals zero and number

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two zero.

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Here we say in our zero course Iris rule or zero x to zero.

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To further elaborate this let's take a break from your vision and see how this all operation changes

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the bit.