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Embedded Systems Applications

Embedded systems development environment

Embedded software build process is a transformation performed by software running on a general purpose computer.

The compiler, assembler, linker and locator are all pieces of software that run on a host computer, rather than on the embedded system itself. Finally executable image run on a target embedded system.

Host (Development) machine communicate to the target various types of interfaces like UART, Ethernet and USB.

Types of computer architectures

1. Based on Program Memory and Data Memory (Harvard and Von Neumann computer architectures)
2. Based on Mechanism (RISC and CISC)
3. Based on Data transfer to the Memory (Little Endian and Big Endian)
4. Based on Types of Address (I/O mapped I/O and Memory Mapped I/O)
5. Based on Instruction Set

Harvard and Von Neumann computer architectures

• It is named after the mathematician and early computer scientist John Von Neumann. The computer has single storage system memory) for storing data as well as program to be executed.
• There is no real difference between data and instructions.
• Data and instructions share the same memory.
• Processor needs two clock cycles to complete an instruction. Pipelining the instructions is not possible with this architecture.
• In the first clock cycle the processor gets the instruction from memory and decodes it. In the next clock cycle the required data is taken from memory. For each instruction this cycle repeats and hence needs two cycles to complete an instruction

• The name is originated from “Harvard Mark I” a relay based old computer.
• The computer has two separate memories for storing data and program.
• Processor can complete an instruction in one cycle if appropriate pipelining strategies are implemented. In the first stage of pipeline the instruction to be executed can be taken from program memory. In the second stage of pipeline data is taken from the data memory using the decoded instruction or address.
• Most of the modern computing architectures are based on Harvard architecture. But the number of stages in the pipeline varies from system to system.

RISC and CISC:

CISC	RISC
Many complex instructions	Simple instructions, few in Number, Few addressing modes
Variable length instructions	Fixed length instructions
Many instructions can access memory	Only LOAD/STORE instructions access memory
mov ax, 10 mov bx, 5 mul bx, ax	mov ax, 0 mov bx, 10 mov cx, 5 Begin add ax, bx loop Begin
The total clock cycles for the CISC version might be: (2 movs × 1 cycle) + (1 mul × 30 cycles) = 32 cycles	While the clock cycles for the RISC version is: (3 movs × 1 cycle) + (5 adds × 1 cycle) + (5 loops × 1 cycle) = 13 cycles
Example: x86 ISA	Examples: ARM, MIPS, PowerPC (IBM), SPARC (Sun)

Little Endian and Big Endian

I/O mapped I/O and Memory Mapped I/O:

I/O Mapped I/O	Memory Mapped I/O
Separate address bus for I/O and memory.	Common address bus for I/O and Memory.
Support IN and OUT Assembly Instructions.	There are no separate IN & OUT instructions. What are the instructions are to communicate memory same instructions useful to communicate I/O.
Separate control lines for I/O. IOR and IOW	No separate control Lines for I/O. Memory control lines only MEMR, MEMW.

Register Plus Memory Architecture and Load Store Architecture

Register Plus Memory	Load Store Architecture
Allows operations to be performed on (or from) memory, as well as registers. If the architecture allows all operands to be in memory or in registers, or in combinations, it is called a “register plus memory” architecture.	load/store architecture divides instructions into 2 categories: • Memory access (load and store between memory and registers). • ALU operations (which only occur between registers).
Example: ADD M ; A <- A + [M	Example: ADD r3,r2,r1

Embedded Hardware

Hardware Required	Desktop Computer	Simple Embedded Computer Ex: remote Controller	Complex Embedded Computer Ex: Mobile Phone
Processor (Bus Width)	High end processor 32 bit/ 64 bit Ex: Intel Processor	Low End Processor 8 bit/16 bit Ex: 8051 (8 bit) ARM Cortex M4	High end processor 32 bit/ 64 bit Ex: ARM Cortex A9
CISC or RISC	CISC	RISC	RISC
Caches and MMU	Yes	No	Yes
Memory	2G to 64 GB	32KB to 128 MB	128 MB to 4GB
Multiprocessor	Supports Dual Core/ Quad Core/ Hexa Core	Doesn’t support Multicore	Supports Dual Core/ Quad Core/ Hexa Core
Sensors	Doesn’t Support Sensor interface	Support Sensors Interface	Support High end sensors interface
External Device Interface	Supports	Once Device manufactured, can’t interface new device to the target.	Once Device manufactured, can’t interface new device to the target.

Embedded Software

Software Layers in the Computer

Software Required	Desktop Computer	Simple Embedded Computer Ex: remote Controller	Complex Embedded Computer Ex: Mobile Phone
Software layers in the Computer
Operating System	Windows/Linux	Doesn’t Support OS.	Supports Windows/Linux/Android
Firmware	BIOS	Whole system develops using firmware	Bootstrap program
Programming Languages	C/C++/Java/html/ php	Assembly/C	Assembly/C/C++/Java/ html/php

At the lowest level are programs that are run by the processor when the computer first powers up. These programs initialize the other hardware subsystems to a known state and configure the computer for correct operation. The software, because it is permanently stored in the computer’s memory, is known as firmware.

Above the firmware, the operating system controls the operation of the computer.

Firmware:

Firmware is software that is programmed into chips permanent/temporary and usually performs basic instructions, like BIOS, for various components, Network cards, and computer BIOS, etc…

Embedded C Programming is also called Firmware.

Embedded C vs General C:

• C is a widely used general purpose high level programming language mainly intended for system programming.
• Embedded C is an extension to C programming language that provides support for developing efficient programs for embedded devices.
• Embedded C has to use with the limited resources, such as RAM, ROM, I/Os on an embedded processor.

Operating System

An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs.

Kernel

Kernel is core part of the operating system. Kernel provides core service like Process management, Memory management, File management, Device and network services.

ARM cores are designed specifically for embedded systems. The needs of embedded systems can be satisfied only if features of RISC and CISC are considered together for processor design. So ARM architecture is not a pure RISC architecture. It has a blend of both RISC and CISC features.

ARM Architecture Features and Benefits:

Features	Benefits to embedded system
High Performance	Ensures the system has a fast response
Low power consumption	Makes the system more energy efficient
Low silicon area	Reduces the size and also consumes less power
High Code density	Helps embedded system to have less memory footprint
Load/store architecture	Used to load data from the memory to the ARM CPU register or store data from the CPU register to the memory; enables the memory access when required
Register bank with large number of working registers	Required to perform most of the operations within the CPU and provides faster context switch in a multitasking applications

In the path of architectural evolution, ARM has contributed many versions of IP cores to the embedded computing world. ARM pioneered embedded products are excelling in every visible spectrum. Since its inception, ARM has migrated over a long meaningful road map starting from v4T ARM7TDMI to v7 Cortex series of architectures achieving many strong milestones in between. It is currently the new era of feature rich ARM Cortex series architectures truly empowering the embedded computing world.

ARM architecture evolution:

ARM architecture v7 profile:

In order to provide a wide coverage of different application domains, addressing their specific requirements, ARM core is evolved into architecture version7 which has three different profiles: the application profile, real time profile and microcontroller profile. Architecture v7 should not be confused with ARM7 which has been explained before under architecture v4.

Application profile (Cortex -A)

Cortex A series of architectures are multicores with power efficiency and high performance. Every Cortex – A implementation is intended for highest performance at ultralow power design. It supports with, in-built memory management unit. Being influenced by multitasking OS system requirements, it has virtualization extensions and provides a trust zone for a safe and extensible system. It has enhanced Java support and provides a secure program execution environment. These architectures are typically designed for high end real time safety critical applications like automotive powertrain system. Some Cortex- A application products are smart phones, tablets, televisions and even high end computing servers.

Real-time profile (Cortex -R)

Cortex R series of architectures are designed for deeply embedded real time multitasking applications. They have low interrupt latency and predictability features for real time needs. It provides memory protection for supervisory OS tasks being in privileged mode. It also provides tightly coupled memories for fast deterministic access. Typical application examples are: hard disk drive controller and base band controller for mobile applications and engine management unit where high performance and reliability at very low interrupt latency and determinism are critical requirements.

Microcontroller profile (Cortex -M)

Cortex M series of architectures have v6-M as cortex M0, M0+ and M1 and v7-M with Cortex M3, M4 and other successors. This series of architectures developed for deeply embedded microcontroller profile, offer lowest gate count so smallest silicon area. These are flexible and powerful designs with completely predictable and deterministic interrupt handling capabilities by introducing the nested vector interrupt controller (NVIC). The small instruction sets support for high code density and simplified software development. Developers are able to achieve 32-bit performance at 8-bit price. The very low gate count of Cortex M0 facilitates its deployment in analog and mixed mode devices. Due to further demanding applications requiring even better energy efficiency, Cortex M0+ was designed with two stage pipeline and achieved high performance with very low dynamic power consumption, reduced branch shadow and reduced number of flash memory access. Cortex M1 was designed for implementation in FPGA. It is functionally a subset of Cortex M3 and runs ARM v6 instruction set with OS extension options. It has 32-bit AHB lite bus interface, separate tightly coupled memory interface and JTAG interface to facilitate debug options. It has three stage pipeline implementation and configurable NVIC for reducing interrupt latency.

Cortex M4 Features:

• Thumb2 instruction set delivers the significant benefits of high code density of Thumb with
• 32-bit performance of ARM.
• Optional IEEE754-compliant single-precision Floating Point Unit.
• Code-patch ability for memory system updates.
• Power control optimization by integrating sleep and deep sleep modes.
• Hardware division and fast multiply and accumulate for SIMD DSP instructions.
• Saturating arithmetic for noise cancellation in signal processing.
• Deterministic, low latency interrupt handling for real time-critical applications.
• Optional Memory Protection Unit(MPU) for safety-critical applications
• Extensive implementation of debug, trace and code profiling capabilities.

ARM Cortex M Programming Model:

The programming model of the Cortex-M4 processors has 18 working registers shown in below Figure. Thirteen of them are general purpose 32-bit registers, three have special uses and two stack pointers.

Which course should be opted in Engineering?

To all the students who are looking forward to take Engineering admission, and to their parents, we would like to give some suggestions about branch selection.

There is no doubt that every student’s first choice is Computer Science only.But, to bring awareness in students, about the enormous opportunities provided by electronics field and about its importance and to encourage them to choose Electronics field, is the main agenda of this blog post.

Why is there so much demand for Computer Science Engineering?

Due to the salaries and lifestyle provided by software industry, not only the students, their parents are also attracted to this field.

Nowadays situation has become such that, job means only software engineer job, engineering means only computer engineering, nothing else is considered good.

As lot of people compete for Software Engineering jobs, only few of them get proper development opportunities.Remaining candidates just end up doing maintenance & support kind of jobs with no proper career growth.

What is the importance of Electronics branch in Engineering?

Nowadays mobile phone has become the basic necessity of human life along with food, clothes and shelter.

We cant imagine life without smart phone.

We cant find a house without atleast one electronic device. There will be atleast a TV and a Set top box to say minimum.

How are these electronic devices made?

Electronic core fields like Embedded Systems & VLSI design and manufacturing fields are the ,main reason that we have all these devices.

Electronics field is no way inferior to Software field in terms of Job opportunities.

Most of the Electronics students are not aware of the opportunities provided by Electronics field, so they are either choosing Software field or moving on to higher studies etc.

As long as the situation is like this, we will have to import every electronics device that we need, from other countries like China or Japan.Make In India can never become reality.

What are the new courses added to Computer science branch, and what are the consequences of adding them?

In this academic year (2020-2021), 6 new engineering courses were added to the computer science department.

Those are

• Computer Science Engineering – Software Engineering
• Computer Science Engineering – Artificial Intelligence & Machine Learning
• Computer Science Engineering – Data Science
• Computer Science Engineering – Cyber Security
• Computer Science Engineering – Internet of Things
• Computer Science Engineering – Networks

Most of the subjects in these courses are taken from the Computer Science Standard Curriculum.They should have been added as Specialisations in M.Tech instead of adding as new branches in B.Tech.

Because of adding these new branches in B.Tech, approximately 19000 new seats got added to Computer Science department alone.Because of the increased seats, most of the students will opt for Computers branches, which will effect core fields like Electronics Civil, Mechanical etc.

As these core fields get effected as no one is opting for them, the technology advancements in these fields will be hindered.If you see countries like China or Japan, they are technologically very advanced.

Why are these countries so developed? Because they give equal importance to all core fields, not just one field. That is why now they are in a stage to manufacture anything on their own and export it to other countries.

Because of the newly added seats in computer science department, all students will tend to choose Computer science branch only.

But we need to understand that increase of seats in a particular field does not mean increase in job opportunities. It means competition is increasing in that field.

One more thing is, technologies like Artificial Intelligence & Machine Learning are no doubt in demand, but these technologies have to be used in electronic devices only.So inorder to use these advanced technologies, we will require electronics basic knowledge.

Which means, Electronics field will continue to provide job opportunities and there will be demand for skilled resources.

So is it right that everyone chooses software field, leaving such an evergreen field like Electronics?

What I want to tell to students and their parents is,choose the field which provides good job opportunities, growth in career along with good salaries and job satisfaction. Choose Electronics Core field.

Let us together pledge to save the electronics core field branches like ECE & EEE. And make “Make In India” possible.

Embedded Software

• C Programming Skills (Function, Pointers, Arrays, and Structures, Bit-wise operations should be your best friends). Master C programming skill. This is the most essential skill for the ECE students today. Without this skill you will find it difficult to enter into electronics core companies.
• Embedded C Programming (Microcontroller Programming)
• Operating Systems Concepts (Process Management, File Management, Memory Management, Inter Process Communication)
• Linux Basics/Commands
• Work on Community development boards.

Resources

• C in Depth by Srivastava and The C Programming Language by K & R
• Operating System Concepts (book) by Galvin

Embedded Hardware

• Computer Organization (Microprocessor,  Microcontroller)
  • I/O Organization (Polling, Interrupt, DMA)
  • Memory Organization (Memory Hierarchy, cache Memory, MMU, Virtual Memory)
• Understand the Digital Circuit thoroughly from AND, OR, NOT gates to Microprocessors.

Resources:

• Computer organization by Morris Mano
• Digital Systems by Morris Mano
• 8086 microprocessor interfacing

Project Work:

Buy a Community development board and apply the C programming skill to do good electronic projects by yourself without copying a single line of code from net/book/friends.

For Freshers, the resume should be mainly about their skill-set and academic details. Here are some tips about how to build your resume, section wise.

• Career Objective Section:
  • It is absolutely unnecessary. The Career objectives are just like heritage carried from your senior’s CV’s to your CV, then to your junior’s. You can safely remove it as it is nothing but copy paste.
  • If you have something of your original, that reflects your real career motto or attitude, you may add it, just to bring some interest.
• Technical Summary:
  • Add a line in technical summary about training attended at Kernel Masters. Course name is Certified Industrial Embedded Systems Developer training.
  • Or add any other relevant course that you have attended at any institute.
  • Update the skillset or technical summary section with whatever topics you learnt at Kernel Masters, or implemented, like socket programming, inter process communication etc.
  • You may also add the major subjects studied in technical summary/skillset, like C Programming, Embedded C with STM32, Operating System concepts, Git, GDB , KGDB etc.
  • Protocol names must be mentioned.
  • Sometimes it may be required that you have to update your technical skillset based on the company’s requirement and Job Description. So keep visiting this section from time to time and update.
• Projects:
  • Add the embedded C project done at Kernel Masters, to your profile above your academic projects.
  • Add Project Title first.
  • Add project abstract / description. Add this in your own words, to reflect how you understood the project in general words. Include some key technical words that help describe the project.
  • Do not copy paste project description from anybody else.
  • Quality is more important than quantity when it comes to projects. You will be validated based on how much practical implementation you have done on one project with perfect understanding, than how many projects you have done.
  • Add the responsibilities handled by you and the technologies & protocols used.
  • Under responsibilities you will have to add details like ,data sheet study, any kind of analysis done, sensors studied etc in bullet points.
  • Academic project should be added only if you are able to explain about it in interviews.
• Experience Summary:
  • Add your experience or internship details if any only if it is related to Embedded field.
  • Add companyname, designation and duration for which you have served at the company.
  • Do not add teaching experience or experience from any other field that is not relevant to Embedded Industry.
• Education Details:
  • Academic percentages, branch or specialization and passedout years are mandatory in education details.
  • Also add the university and college names for graduation and post graduation.
• Personal Details:
  • Personal details section is not usually required if you are providing your residential address at the top.
  • If you want to provide, put your date of birth & Residential address. Family details are not required.
• Contact Information:
  • Add a valid mobile number and a mail id that you regularly use and check. The mobile number that you provide in resume, must always be available.
  • Make sure your email id that you provide has a professioal looking user name that shows your full name as part of it.
  • Do not use any unprofessional & funky mail ids like mylifemywish@gmail.com.
  • Better to add your residential address to give the employer an idea of your current location, there by decide the mode of interview.
  • Add your SkypeId.
• Other Key points to Note:
  • Name your resume file in this format “FullName_Fresher/x+exp” Full name is mandatory. Never name it like “my_resume”, “resume”,”resumeupdated” etc. Resumes wrongly named will be discarded.
  • Send only word documents to me, if you are under my placement assistance program (only for Kernel Masters students).
  • Wish you All the Best.