How to start learning embedded systems a complete roadmap

         How To Start Learning Embedded Systems: A  Complete Roadmap    Amit Rana  kitflix.com    1        Are you looking for how to learn embedded systems?  Are you looking for a clear roadmap to start learning embedded systems?  Are you a complete beginner and need no-fuss clear guidance on studying and  experimenting with embedded systems?  We’re going to cover all above questions in this tutorial And we’re going to see a clear  roadmap to start learning embedded systems We’re going to see what it takes for anyone  to get started with embedded systems and what is the flow that one can follow if he or she  wishes to excel in learning and developing embedded systems.  This tutorial is specially created for complete beginners to give the simplest guide to start  learning embedded systems quickly and understand all that is there to learn about it This  tutorial will help you map your learning objectives based on where you are at this stage.  Even if you’re in the middle of something like you understand little bit of Arduino  programming, this tutorial will help you shape your knowledge and is intended to provide  guidelines to excel So lets get started.    kitflix.com    2      What is an embedded system?  An embedded system is a dedicated computerized system which can perform one  dedicated task or similar associated tasks Let’s take an example of a temperature  controller This type of temperature controller is very commonly used in wide variety of  manufacturing industries The typical jobs of temperature controller are  ● ● ● ● ● ● Read the temperature value  Display the temperature value  Configure a set point for temperature value  If the temperature is below the set point, make the output device off  If the temperature is above the set point, make the output device on  Repeat the cycle  As you can see in above steps, its obvious that we not expect an embedded system to  stop functioning An embedded system is always running unless its power off or turned of  by the user So to create such simple system what are the options we have?  ● ● Analog + Digital Design  Embedded Design  kitflix.com    3    Analog Design  Now such a system like a temperature controller, can it be built using a simple analog  circuit? Yes off course it can be developed By using temperature sensor, analog to digital  converter, the seven-segment display drives and lot of conditioning circuits and digital  timer circuits We definitely can create such a system for temperature controller, but it  requires a lot of design efforts Moreover, if we want to change anything or any element of  this system, it’ll be very difficult to make changes as we’ll need to reconfigure lot of  component values itself Even if you want to add some time delay or some timed  operations, you’ll need to make lot of changes to the system So what is the option here?  The option is instead of creating a simple circuit design, make it using embedded system  principles.  Embedded Design    kitflix.com      4    An embedded design if very simple to build All it will consist of is the microcontroller unit  which will the job of sensor reading, display driving and output device (relay) switching.  How it does all of this, how it prints value and how it reads the temperature sensor and all  is controlled by a software written inside the controller An embedded controller can not  function directly as compared to normal analog or digital circuits Instead an embedded  microcontroller needs a program written in its memory which will the job of controlling  the devices The microcontroller is a reconfigurable IC The pins of microcontroller can do  the job of input or output or analog input and so on Depending on the software written,  the pins of the microcontroller can behave differently In order to get excelled in  microcontrollers coding, we need to understand the microcontroller architecture After  studying the microcontroller architecture well, we can start writing the programs for it But  because of this big limitation, many people can not dive into embedded systems directly.  And here the Arduino board comes into the picture In order to program an Arduino board  we not need any knowledge of the underlying hardware which is called the  microcontroller Board We’ll discuss about the Arduino board in details soon.    How an embedded system is built?  So, a system which is built using this type of microcontroller as the heart of the  system is called as an embedded system An embedded system has all the related  input and output devices interfaced directly to the microcontroller or connected to it  via some driver circuit Depending upon the application at hand, an embedded  system may have few or all of the components shown in the below diagram.    kitflix.com      5      What are the different components of Embedded  Systems?        Just take a look at the above block diagram It’s a very simple block diagram of an  embedded system Mind well, when I say simple, it really is The block diagram hides  almost everything that is complex and gives a bird eye view of an embedded system The  embedded systems block diagram shows mainly components of embedded system.  Inputs can be usually coming from switches, or sensors In the example of temperature  controller, the inputs will be switches to accept the setpoint and the temperature sensor  itself Just like, a plant watering system will have input as moisture level sensor.  Controller is the heart of an embedded system A controller’s job is to process the given  inputs and generate outputs For a temperature controller, the job of the controller inside  is to read the temperature value, read the switches Now compare the temperature value  with set point, and control output devices Controller cannot any of these things out of  the Box and every controller needs a software sitting inside it to these things This  creates a demand for software programming in embedded systems.  The most popular controllers used in embedded systems are  kitflix.com    6    ● ● ● ● ● Microcontroller  Microprocessor  PLDs (FPGA / CPLD)  System on Chip (SoC)  Outputs  This is the sole purpose of designing any system We need to generate outputs Usually  outputs are generated using a variety of driver circuits that can create output action.  Microcontroller (if used) can only generate small signals as their output +3.3v/0v or +5v/0v  as output voltages These voltages are very small and cannot drive any output device  directly and hence we need something called as output driver for turning things on or off.  Outputs of embedded systems are in form of below examples with their respective drivers  ● ● ● ● ● ● ● ● ● LED On / Off (No Driver)  Devices turning on / off (transistor + relay driver)  Motors rotating with varying speed (motor driver)  Buzzer On off and sound generation (no driver)  Fan on / off (transistor / relay / thyristor driver)  Sending SMS (GSM Module)  Sending data over internet to for remote monitoring (wifi interface)  Displaying data on a screen (LCD / LED screen interfacing)  And many more such things  kitflix.com    7      Where Arduino fits in embedded Systems?      You’re reading this tutorial means one thing is sure, you’ve heard about Arduino 😊.  In an embedded system, generally, the most emphasis on study is given for understanding  the controller The developer of embedded systems has to be very good at understanding  the microcontrollers used in the system with all of their instructions and way of writing  programs for them Every microcontroller is equipped with some or all of below-mentioned  features which are used for properly programming an embedded systems  ● ● ● ● ● ● ● ● ● Input / output ports  Timers / counter  Serial Ports  Memory (RAM / Flash / EEPROM)  Analog to Digital Converter  Digital to analog Converter  Protocols interfacing (I2C / SPI)  Interrupts ( To make processing faster and solve programming challenges easily)  And many such user interfaces are on-chip  kitflix.com    8    A single-chip microcontroller has all such features on the chip In order to use any of these  features, the microcontroller developer creates some unique way of configuring the  microcontroller.  ● ● ● First, there are unique instructions for every microcontroller, which can execute  some job like reading / writing data from memory / Input-output ports / all the  registers inside the controller.  Secondly, there are many special function registers inside the microcontroller And  each feature may have one or many Special Function registers inside the  microcontroller.  The study of the Instruction set and all the internal register organization combinedly  is called a study of Architecture of microcontrollers  So every embedded systems developer has to be very good at an understanding of the  microcontroller architecture as well as the knowledge of inputs and outputs to be used.  Every electronics/computer engineering student usually learns this as part of their studies  and anyone else who is interested to excel in microcontroller studies has to study this on  their own One thing is sure that the proper understanding of microcontroller architecture  is a must.  But  What about those hobbyists/artists who don’t know about microcontroller and still want to  make embedded systems?  For exact people like these, who don’t want to study architecture and get started  developing systems faster and smoother, in 2005 Arduino boards were launched in Italy.  There is a long history behind Arduino boards which can be read​ ​here​ The sole purpose of  Arduino is to enable non-techie people to get started with designing hobby projects using  embedded systems.  But over the years, due to the open-source nature of the entire Arduino system, millions of  people started using it including seasoned developers for very simple reasons  ● ● ● ● Lots of clean libraries available for almost every single interface out there  Free and open source  Quick prototyping is possible  It’s cheap  As of writing this tutorial, Arduino is undoubtedly the number hardware prototyping  platform And there is no need to take any survey on that Everyone will agree with this.  This is how Arduino slowly got adjusted in the crowded market of microcontrollers.  kitflix.com      9    But what is Arduino anyway?  Arduino is a microcontroller-based board that is ready for usage You don’t need to study  the microcontroller architecture in order to use Arduino You just should be able to read  the board; understand basic English and you can get started with programming Arduino.  I’ve written a separate tutorial about it which can be found h ​ ere              Steps to Learn About Embedded Systems    kitflix.com    14    LEDs      LED’s are perhaps the most interesting electronic component that we use in circuit LED’s  are (Light Emitting Diode) components which can emit a specific light It can be RED, Green,  Blue or Yellow LED’s require very less voltage to turn ON (typically 3v) and they have a very  long life We see LED’s in power indicators in almost any electronic appliance The power  light we see on TV, DVD, microwave, in TV remote control are all LED’s We have LED TV’s  now a day’s which uses LED’s to give the backlighting to the LCD Panel in it More about  LEDs is here  Switching devices: relays  kitflix.com    15      Switching devices and circuits are needed to turn on / off devices using microcontroller  output Usually, the output of microcontroller board like Arduino or any other  microcontroller is only a digital signal This digital signal can have a value of either or 0.  Electrically, means the operating voltage of microcontroller and means the ground  voltage Usually, stands for +5v or +3.3v and stands for GND of DC supply or negative of  the power supply circuit This small voltage cannot turn on / off a physical device like a light  bulb So, this voltage is given to a transistor which turns on something called Relay This  relay then can switch the major AC appliances.  Understanding of basic C Programming  kitflix.com    16      Microcontroller is programmed using instructions This is called assembly language  programming In order to write effective programs faster, C programming is used A  separate software called cross compiler is used which can convert the C program to  microcontroller understandable code This microcontroller understandable code is then  created in a special file format called a hex file This hex file is then burned or written in the  permanent memory of a microcontroller called flash memory Microcontroller reads a  program from flash memory and executes the program accordingly This whole process is  called embedded C programming There are various Integrated Development  Environments for writing embedded C programming These IDE combine the cross  compiler of microcontroller and text editor to give a smooth coding experience to the  programmer The choice of IDE depends on the microcontroller being used For example,  Arduino uses the Arduino IDE Various other microcontroller uses different IDE tools Some  of them are free, some are commercial versions Here’s a shortlist of IDE’s used for various  microcontrollers  AVR series microcontrollers by atmel (Now Microchip)  ● ● ● ● Atmel Studio  AVRGCC Programmer notepad  codevisionAVR  mikroC Pro for AVR  kitflix.com    17    Microchip PIC  ● ● ● MPLAB  mikroC Pro for PIC  CCS C Compiler  8051 and ARM architecture  ● ● ● Keil Microvision  Tasking  IAR Embedded Workbench  Your first microcontroller: Arduino    Now you got the idea of what all to study in embedded systems It's best to choose with  Arduino if you’re a beginner Arduino provides easy access to microcontroller features with  the help of ready-made libraries and software tools Using Arduino will be the first step to  enter into the embedded systems world In order to study about Arduino, simply grab an  Arduino board and start using it You can download your first C program to Arduino very  fast, mostly within minutes In order to use Arduino, you first need to install the Arduino  IDE on your computer Arduino IDE can be found at​ ​arduino.cc​ Depending upon your  operating system you can download the appropriate and latest version of Arduino IDE.  Once you have the board and IDE installed, you’re ready to get started with coding in  kitflix.com    18    Arduino You can follow the below video to see how you can get started with Arduino and  download your first program.  https://youtu.be/cKYMasBGj1g    Understanding controller IO      Once you download the first program on Arduino for blinking LEDs, the next step is to  understand the nature of digital Input and output Digital input and output of Arduino  works with simple functions You can generate +5v or 0v output on any Arduino pin You  can also read the input pin on any Arduino pin, but for reading voltage on any Arduino pin,  it must be either 0v or +5v Arduino reads the input as LOW or HIGH LOW means volt  and HIGH means +5v We can read input using a  ● Push-button  ● Sound sensor  ● Moisture sensor  ● Infrared proximity sensor  ● Many different modules  kitflix.com    19    Reading inputs is made really simple with the digitalRead() function of Arduino.  Understanding IO interfaces, like a buzzer, Relay,  digital sensors, LCD, etc      After understanding the basic digital input and output, next step is to understand what all  you can with these functions Now that you can read and write digital signal values,  there are lots of possibilities open for you to create a number of different embedded  systems Even this much knowledge will get started with your hobby projects which can use  a number of different interfaces like  ● LEDs  ● Switches  ● Sensors  ● Relays  ● Buzzer  ● Speakers  kitflix.com    20    ● LCD  You don’t need to understand everything with respect to Arduino or embedded systems to  create a hobby project For example, how to create a distance meter using the ultrasonic  sensor? You need just enough knowledge of Digital IO of Arduino and you can connect an  ultrasonic sensor to Arduino with LCD and measure distance and print it on the screen.  Interfaces using GPIO, stepper motor, DC Motor, etc    With simple input and output, you can control many different devices except simple relays.  Relays are good to turn on/off any appliance but there are many other actuators who need  controlling These actuators include stepper motors, dc / ac motors, servo motors The  primary job of a motor is to provide a rotational force A motor converts electricity into a  rotational force for performing some action It may include a robot movement, or a 3d  printer or a robotic arm And each type of motor requires a controlled supply given to it DC  motors need an H-bridge driver circuit AC motors need thyristorised control circuit and  servo motor needs a PWM pulse.Most of the motor’s speed can be controlled by a  time-varying digital signal given to them This signal is called PWM PWM is pulse width  modulation PWM signal means the digital output from an output pin which is not HIGH all  the time; instead it’s continuously made HIGH / LOW with varying duration of High pulse.  This high-frequency pulse is responsible for the control action of motors Most of the  kitflix.com    21    microcontrollers like atmega328 (heart of Arduino board) have on-chip PWM capability.  A clear understanding of PWM helps us design better control circuits.  Serial Port or UART  Every microcontroller like atmega328 (heart of Arduino Uno Board) has at least one serial  port on it Serial port, technically called as UART is a module on the controller chip which  allows the microcontroller to perform asynchronous serial communication This  asynchronous communication is made possible with wires which are TXD and RXD Apart  from connecting these wires, we also need to connect the GND wire from microcontroller  to the device with which we’re communicating   TXD of microcontroller goes to RXD of the device with which we’re communicating  RXD of microcontroller goes to TXD of the device with which we’re communicating.  The speed of communication needs to be set before initializing communication Since its  asynchronous communication, there is no clock shared Hence for synchronization, baud  rates or bits per second of communication have to be pre-decided and set into the  controller as well as the device with which we’re performing microcontrollers serial  communication Learning about Serial port of microcontroller opens up options to  interface with many interesting peripherals like  ● ● ● ● ● Bluetooth module (helps a mobile communicate with controller)  RFID Reader  GPS Receiver  GSM Module (send/receive SMS and calls)  Wifi interface     kitflix.com    22    Understanding communication protocols, Serial, i2c,  SPI    While studying about the devices which can be interfaced with a microcontroller, it's very  clear that only a few devices can be connected to the IO pins of any microcontroller.  Because the number of input-output pins is limited, we cannot connect as many devices as  we want to a microcontroller at the same time Of course this limitation can be removed by  using a higher microcontroller like atmega2560 which has more IO pin But this can not be  always done due to cost and size constraints.  In order to tackle such issues, some simple communication protocols are developed by  industries to communicate a microcontroller with a number of different devices at the  same time using the same common wire connection And the most popular such  communication protocol is called I2C which was developed by Philips (now NXP) Many  other manufacturers call I2C as TWI Because Philips invented I2C, only they use the name  Inter IC Communication or I2C and others use a generic name like Two Wire Interface (TWI).  I2C allows a microcontroller to communicate with up to 127 different devices using just 2  Wires These wires are SCL and SDA Not to mention, the microcontroller can only  communicate with one device on this bus at a time Hence I2C is slower and usually used  while interfacing with peripherals where speed is not a major concern like sensors.  Most common peripherals that support I2C protocol  ● Real-Time Clock  ● Accelerometer sensor  ● Digital Compass Sensor  ● Gyroscope sensor  kitflix.com    23    ● Analog to Digital Converters  ● EEPROM Chips  Similar to I2C, there is another protocol called SPI, which was developed by Motorola Since  communication is happening on only lines, I2C is slower So when high-speed  communications are needed, SPI or serial peripheral interface is required SPI utilizes a  full-duplex synchronous communication with Serial Data In, Serial Data Out, Clock, Reset  and Chip select signals SPI allows for much faster communication and usually used when  high-speed data transfer is needed like memory card storage.  Popular SPI chips  ● Memory Storage, SD Card  ● EEPROM  ● Function generators  ● ADC and DAC’s  Interfaces based on communication protocols,  ethernet, wifi.    kitflix.com    24      With the same I2C and (or) SPI Protocols some advanced network interfaces can also be  interfaced with the microcontroller which allows the device to get connected to a LAN A  connection may be to a Lan or full internet connectivity is also possible This internet  connectivity then leads to a much larger application area we call as Internet of Things With  a microcontroller, we can interface below-mentioned network interfaces to get connected  to internet  ● Ethernet Interface Controller (SPI Protocol)  ● Wifi Interface (SPI / Serial)  Understanding microcontroller (Atmega328)      With Arduino, we can use many features of microcontroller but still not all of them In order  to make the Arduino functional, some things are disabled by the Arduino firmware and  hence you don’t have access to the entire feature set of the controller And although as  powerful it may be, most professionals and product development firms still consider  Arduino only for amateurs So, if you want to get a job in Industry, then you need to know  the bits and pieces of embedded development from scratch; and it begins with an  understanding microcontroller With Arduino, we got the bigger picture of what things can  be done using a microcontroller, the next obvious step is to understand how all that can be  done using Raw microcontroller coding And in order to that, you need to first choose a  controller If you’ve used Arduino Uno before, then you have already used atmega328p  kitflix.com    25    which is the microcontroller on Arduino So next best thing is to open the datasheet of this  controller and start reading it.  How to read microcontroller datasheet        A device datasheet is the user manual of an IC provided by the manufacturer Just like we  get a user manual when we buy a new microwave oven Consider if the microwave oven  manufacturer doesn’t give a user manual with their product, what will happen? We won’t  be able to use it properly Hence probably, we won’t buy it While the microwave is still a  very simple device, an Integrated Circuit is a very, very complex one Hence the  manufacturer provides something called a datasheet for every device they produce The  purpose of datasheet is to enable the user to understand the IC and start using it easily In  a similar context, a microcontroller is also an IC, albeit a much more complex one So, the  kitflix.com    26    microcontroller also gets a datasheet We can download the device datasheet if we know  who manufactured it from their respective websites Otherwise, you can just web search  with the name of the IC and you’ll find the datasheet.  Here’s a sneak peek of Atmega328 microcontroller datasheet’s first page      kitflix.com    27    The datasheet provides with every single detail about the device we’re studying But  reading datasheets directly is not very simple for a beginner It’s very confusing because  every manufacturer organizes and shows data differently But usually, there are some  common grounds whenever you view the device datasheet of any IC Be it microcontroller  or a simple Op-Amp, there are some common things that are there in the datasheet and  understanding them will make things simpler They are as follows    ● Features  This section contains a birds-eye view of the entire controller It lists all the features of that  microcontroller in a single list view Just by reading this page, you can understand most of  the features of a microcontroller.  ● Pinout Diagrams  This section usually contains the pinout diagrams of the various packages of a  microcontroller The pinout in PDIP package as well as all the other SMT versions of  packages This section gives the user the pin number and names If you want to create a  package of this device in your favorite PCB design software, then you’ll need this section.  Also, it’ll help a programmer understand which pins are GPIO and which pins are for timers  and serial ports and I2C and so on  ● Pin functions  In this section, the job of each pin is described in detail We’ll understand which are power  pins, which are oscillator pins and which are gpio pins Most microcontrollers have more  than one function associated with every single pin, and all of them will be described in  detail over here.  ● Internal Block Diagram  This section gives an internal block diagram of the microcontroller In theoretical studies, its  called the “Architecture of Microcontroller” The name justifies because this block diagram  shows everything that is there inside the microcontroller IC But now every circuit is laid out  in detail Instead, it gives a complete overview of all that is inside the controller It helps to  know things better about the controller.  kitflix.com    28    ● Electric Specifications  This section details the different electrical specifications of a microcontroller IC All the  electrical specifications including  ● ● Maximum and maximum operating voltages, IO voltages  ○ Operating temperature ranges  ○ Minimum and Maximum Current and power consumption ratings  ○ DC Characteristics  Features Explanation  This is perhaps the biggest section of them all This section shows all the workings, the  internal registers descriptions, how to configure each one to be used And how to use every  single feature of the microcontroller This section has it all Whatever that you're trying to  use, be it an interrupt or timer, or ADC / DAC, you can use it by following this section here.  Concluding Remarks  Now that you've got a fair idea of what are the embedded systems, it'll be good idea to get  started with your own experimentation There are plenty many tutorials available on the  particular microcontroller which you want to start learning embedded systems If you want  to learn embedded systems on arduino, we've a detailed course on it​ ​here​ Thanks for  reading.  kitflix.com    ...       Are you looking for how to learn embedded systems?   Are you looking for a clear roadmap to start learning embedded systems?   Are you a complete beginner and need no-fuss clear guidance on... get  started with your own experimentation There are plenty many tutorials available on the  particular microcontroller which you want to start learning embedded systems If you want  to learn embedded. .. studying and  experimenting with embedded systems?   We’re going to cover all above questions in this tutorial And we’re going to see a clear  roadmap to start learning embedded systems We’re going to