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Hello.

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Welcome back.

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As you may know memory holds code and data for the CPI to process and the input output ports are used

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by the CPI to access input and output devices into microcontroller.

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We have two types of input output.

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They are the general purpose inputs outputs also known as TPA 0 and the special purpose input output.

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The GPI or the general purpose input output are used for interface and devices such as LCD switches

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LCD keypad DC motors etc..

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Special Purpose inputs outputs have designated functions functions such as analog to digital conversion

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digital to analog conversion time I use sage and universal asynchronous receiver transmitter order you

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out to.

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We're going to find on our microcontroller the same thing being configured as either a GPI or or a special

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purpose IO and would have to tell the microcontroller that we want to use this being for special purpose

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or we want to use it for its normal general purpose right in a microcontroller Ps are grouped into ports

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such that we have a port a port B port C etc. so each port has a number of pins.

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For instance pin a one stands for being one of port a in the same way.

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If you see a pin such as this one pin E3 stands for pin 3 of port E.

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So when we access in these pins we've got to tell the the development environment the ports and the

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PIN number as well.

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So all microcontrollers have this name convention.

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They've got the pins grouped in ports right.

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But when you're using when you're using platforms like that we know and and and that you wouldn't need

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to indicate the ports of order pin d Are we know Raphael the embed wrapper has taken care of all of

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that and if renamed these pins into simple names such as P1 through pin thirty P one through P 30 without

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indicating whether P 1 through p 5 fall under port E and then P 5 through P 10 for London port to be

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when you code in an embed or at when you need not worry about all of that.

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Now when you are doing bare metal coding you need to know the ports as well as that PIN number of the

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top of the particular pin you want to access.

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Now let's talk about buses so moored in the cortex microcontrollers have two types of buses.

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They've got the advanced peripheral bus and they've also got the advanced high performance bus the advise

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pay for bus is often written us APB and the advance high performance bus is often written as HP and

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we use in the advanced pair for bus you you will require a minimum of two clock cycles to access a peripheral

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but with the advance high performance bus you can use even one clock cycle to access peripherals and

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we're going to go into the datasheet of four different cortex microcontrollers four from three different

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vendors and we'll see that these buses exist in all the microcontrollers whether it's it's a microcontroller

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from an XP whereas from Texas Instruments or whether it's from SD they've all got this.

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So let's take a look at the data sheet and locate these buses because one of the purpose of this course

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is to enable you to be able to go through the data sheet and the use of manuals of any microcontroller

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you're dealing with in order to work with peripherals and deal with things on your own as you improve

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your embedded development skills.

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Right now let's see how to locate the data sheets of our particular microcontroller and take a look

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at the deposit structure in the microcontroller.

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So I'm just going to go to Google and just search the name of the microcontroller followed by the word

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data sheet.

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I'll come over here too.

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Let's start with the SDM that's to see SDM 32 for 1 1.

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R E the version of F for microcontroller on my discovery board is this 1 4 4 1 1 RB but you can search

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this or search the F for 0 version.

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The information should be the same really so I'll just select data sheet here and click here to go to

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the SD website and decide if called download data sheet or what.

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Yes so I can click here

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and this opens right so that there's the data sheet and that's the reference might know the data sheet.

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Use a summary of these particular MCU.

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It tells us the number of player floors the the power consumption limits and things like the in the

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block diagram you can think of the data sheet us the summary and the reference manual as indeed the

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reference manual.

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So the data sheet of A has one hundred and forty nine pages the reference manual often has over a thousand

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pages.

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Right.

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So I'm going to scroll down here.

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We should have the block diagram down here somewhere the block diagram of the system OK.

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Here we go.

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So I'm just going to click here to zoom and over here.

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So this the this the diagram of our microcontroller the block diagram and as you can see it's called

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HB bus here.

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This the HP bus and anything you see connected to this shows that we can connect to these peripheral

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use using the HP bus for instance we can connect to for instance PPR you put a can use a HP bus port

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b you can use HP as well but C put D port H can use HP right but it's not always the same for all peripherals

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this one here is an APB bus as you can see the name indicated here APB 1 we've got APB to here.

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So when coding we would keep in mind that we cannot initialize let's say the U UT or the U side too

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and try to initialize a using the HP bus because you say it hasn't got a HP bus we work with a user

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to use and the APD bus.

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Right.

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So this the bus structure of the SDM that's to F4 and we'll be revisiting the the MCU like I mentioned

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before one aim of this course is to give you the skills that would allow you to navigate the data sheet

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and the reference my law to solve your own problems as you improve your embedded development skills.

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So this the SDM board.

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Right next we're going to see other three boards or based on the architecture but from different manufacturers

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and you see that they've all got the HP an APB bus.

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OK.

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So I'm going to come over here and I'm going to go to Google and I'm going to search t end for C. 1

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2 3 g it's 6 p.m. and I'm going data sheet.

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This the TVC bought from Texas Instrument which opened this and it's open over here.

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Should I get a data sheet has over a thousand pages by.

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Fine.

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We still look at what we're looking for.

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Often the block diagram is somewhere below the table of contents and the list of figures.

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So you just need to scroll down sometimes in fact they didn't get on quality block diagram.

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They've got different names for this one way of search and quickly is to press control and F together

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and search the word.

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You look in force or just a block diagram over here.

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Shit over here.

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It says cortex M for F process or block background.

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So the f here means the cortex M4 has a floating point unit as well not all cortex and for floating

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point units.

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So this the CFMEU block diagram we have over here but we want.

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We don't want a block diagram of the process or we want to block diagram of the entire microcontroller.

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Remember the process or is just one part of the microcontroller right.

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We can come over here to see series overview.

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Right under the overview there should be a diagram.

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Here you go.

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OK so over here.

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This is the diagram for the Texas Instruments board.

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The team 4C 1 2 3.

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As you can see we've got the advanced high performance bus the HP bus here and we've got the advanced

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pair for bus here in the same way.

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Only those with the arrow connect into the HP bus can use the HP bus those without the arrow connecting

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to the HP bus.

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Can we use the HP bus.

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So let's see an example of what I mean.

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This the HP bus we've got over here.

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For instance this payphone on us.

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SS I cannot use HP as I can see its arrow is pointing to the APB right.

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And this ADC here this on comparator here is pointing to AP In the same way the twelve bit ADC is pointing

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to AP and we have the DME the DMA is able to use both the HP bus and the AP bus right and we've got

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a time here the watchdog time on using just the APB bus we'll talk about all of these air force later.

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So you need not worry this is just to show you the bus structure that exist in the various microcontrollers.

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Okay so let's see the third microcontroller.

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Let's try the one from an XP.

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I'm going to search and XP the popular LPC 1 7 6 8 microcontroller

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on this the embed board.

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Yeah but we won the data sheet.

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You can see use a manual as well.

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Okay.

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So open the user manual for LPC 176 exits slash 5 x so search they use a manual for LPC 176.

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Okay.

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And it's open over here.

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This is it right in the same way.

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We can just to control F and block that from here.

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So this what it means to be an embedded systems developer.

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You should be able to work with any microcontroller you provided with.

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Often people keep themselves in the comfort zone thinking OK because I work we just SD microelectronics

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it's going to be hard to switch to a different vendor.

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But that's not a case if you know how to use the data sheet and navigate to things like the data sheet

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and the user manual.

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You'll be equally comfortable working with microcontrollers from different Silicon manufacturers right.

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Sure.

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OK we've got this.

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It says simplified block diagram Nass can see we've got the buses here and this over here.

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This bus comes here and this difficult in the air system difficulty mortally at HP matrix.

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So this bus here is an APB matrix and as HB 2 APB bridge there's a bridge here.

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I can see all of these peripherals use the APB bus hence the are called the APB slave.

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Group 1 these peripheral issues the APB as well.

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And there is an HB to APB bridge over here.

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Right.

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So these hard core core text M standards they exist in all core text source.