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Microcontroller is designed from transistors, millions and millions and even billions of transistors are miniaturized into small size, to form building blocks of MCU, and these building blocks give them ability to control anything. The building blocks of MCU are: CPU, Memory and Peripherals. We will dive into these blocks after couple of minutes. The designing of these transistors is an art and science behind the chip designing. This art of technology is called as VLSI( Very Large Scale Integration). And Once the designing is done then these Chips are fabricated/manufactured to give us a final by product that is physical MCU chip. And This part is done by fabrication companies like TSMC. And after that fabrication, the packaging/assemble of integrated chip happens so that these millions and millions of transistors which are minitiasuered are enabled for practical usage in electronic devices.

And after that programming on these MCU and extra circuitry around these MCU’s is developed to make the MCU do any specific task till eternity. These part are referred as Embedded Systems, in which software and hardware around the microcontroller is developed to make it use in final end product.

Part of Software development for Microcontroller is called Embedded Software Development and part of Hardware development for MCU is called Embedded Hardware Development.

In this video and chapter we will just get ourselves stick to microcontroller technology, and focus on what things are involved for learning and using microcontroller. Though their are many topics and technologies which can be deep dive, which we will do in separate videos.

Pins in Microcontroller:

Pins of microcontroller are physical end points through which MCU interacts with the outside world. Microcontrollers have pins through which it transfers and receives the data to the outside world.

Now you take any microcontroller, every microcontroller will have 2 types of Pins:

Power Pins: Power pins are pins of MCU through which MCU gets electric Power. All of the Microcontroller operates at 5 Volats. In Every Microcontroller, we will find their are pins by name of VCC/GND. Vcc is one on which +5/+3.3 volts is given and GND is grounded. Apart from these their are other Miscellaneous Power pins for analog circuitery and all.

Input/Output pins: Input output pins are the pins which act as an mediator to transfer data to the peripheral’s of MCU, which need data from the otside world. T Peripherals like that of Communication, Digital and Analog, Programming and Debugging, Reset and Clock pins need some MCU pins for exchange of data to outside world. So these pins are categorised in terms of these peripherals of MCU.

• Like UART peripheral which implements the UART protocol, need RX and TX pins for doing UART communication. So MCU has pins of this nature termed as UART pins: UART_Rx and UART_Tx.
• SPI peripheral which implements the SPI protocol, need MOSI/MISO/SCK/CE pins for doing SPI communication. So MCU has pins of this nature termed as SPI pins.: SPI_MOSI, SPI_MISO, SPI_SCK, SPI_CE
• Timer peripheral which is used to generate digital pulses or sample digital pulses, need

So we can divide input/output pins of mcu in terms of these peripherals present in mcu.

1. So their are Communication peripherals like: CAN, LIN, UART, SPI and etc. For each peripheral their are corresponding Communication pins
2. Digital and Analog peripherals like: TIMERS, GPIO, ADC, DAC and etc. In these peripherals their are concepts of channels. The Pins which are their for these peripherals are referred as channels.
3. Programming and Debugging pins: JTAG, SWD, ISP and etc. These are factory default pins, which we dont change in most of the cases.
4. Reset and Clock Pins: XTAL1 and XTAL2, system reset and bootloader pins. These are also factory default pins, which we dont change in most of the cases.

Now for referring to these pins of MCU, their are concepts of Ports in Microcontroller. Dont worry its not adani ports!!!!!

Basically grouping is done of MCU pins and each group is called as PORT. And these groups are named according to alphabetical order. PORTA, PORTB, PORTC, PORTD and etc. And in each port max to max 32 pins can be fit in. So Pins are named as PTA1, PTA2…. PTA31, PTB1, PTB2, PTB3 …. PTB31, PTC1, PTC2, PTC3 ….. PTC31 and etc. Now how many ports and pins in each port are their can varry greatly from microcontroller to microcontroller. Some Microcontroller have only 2 ports and some have more then 8 ports. Some microcontroller have 2 pins per port and some MCU have 32 pins per port.

In detailing for each peripherals categories and their pins we will dwell into video ” What are peripherals in microcontrollers”.

Clock in MCU

Now microcontroller technology has a concept of clocks. These are not watches that we have or in walls!!!!!

One can see that their are many components in a microcontroller: CPU, memory and then number of peripherals. All these units should worked in a synchronized way. By synchronized way we mean that when peripheral receives or transmits the data at that time, memory of MCU should also be updated and then simultaneously CPU should process the data. If this synchronization is not mainatned, means new data on peripheral comes in or out before that data gets processed properly will cause errors and mishaving.

For this synchronization, in microcontrollers their is concept of clocks. Clocks provide a Frequency of digital pulses at which these systems should operate. Faster the frequency faster the MCU can execute and process the data.

So clock is needed to generate frequencies for synchornization of various components of MCU. Take it in a way the human body works, if brain is not synchronized with our hands and legs then we will not be able to move in a desired way. Sameway if clock is not their then MCU units will not be synchronzed with each other and work in undired way.

So now this frequency is generated by electrical circuits called: oscillators. Oscillators are eternal part microcontroller. Oscillators are electrical circuits that can convert the current from DC source into a continous alternating digital waveform. As MCU are powered with DC source, so oscillators convert this DC source into digital waveforms. And then this digitak wavewforms are fed to number of units.

So, these oscillators are clock sources for microcontroller’s to generate the clock frequencies. And their can be 2 types of Clock sources:

Either internal oscillator or External Oscillator.

In the case of Internal Oscillator, MCU chip in it has built in oscillator minitiasered into it. And in the case of External Oscillator, we attach the crystal oscillator to the clock pins of the microcontroller.

Now thier are 2 concepts used in clock configuration of MCU:

First is concept of PLL. That is abrievted as Phase Locked Loop, which are used to increase the MCU system clock frequency. PLL are another types of electrical circuits which can enhance the output signals frequency on feeding them with input signal. So normally first Clock source is finalised and if we need more clock frequency value to run the systems then PLL is used to get the final Clock frequency. If clock frequency is sufficent from internal/external clock then no PLL is used.

Another concept is of Divider/Prescaler in clock configuration, just like their is PLL for increasing the Clock frequency, their is a clock divider circuit, that reduces the frequnecy of an input clock signal to create a lower frequency clock signal.

Now after generating the frequency from clock sources, comes the concept of clock destination. That is in which all systems this generated clock has to be fed into. These are termed as clock destination’s or clock consumers:

And mainly their are 2 clock consumers:

• Peripheral clock control: This module basically configures, controls, and generates the clock for each of the peripherals of the MCU via system clock frequency
• Internal bus clocks: These are buses which are connecting peripherals to CPU systems. So we have to configure clock for these buses to.

Microcontroller to Microcontroller, their can be different naming convections and process to configure the clock. We will dive deep into how to confugure clock of microcontrollers in a spearate video: . In this video we will return to our topic of microcontroller technology introduction.