Embedded Systems & Robotics Basics

Submitted to :

Mr. Ritesh Saraswat (guide)

Ms. Seema Sharma (co-guide)

Submitted by:

Sachin kr. Jain

Subhash choudhary

Vivek kr. gupta

Embedded Systems

A embedded system is a microprocessor or microcontroller based electronic device used for specific task.

It is designed to perform operations which minimize (or even completely avoid) need of human control.

Types of embedded systems

1. Real time embedded system (a) Soft real time embedded system

(b) Hard real time embedded system

2. Non real time embedded system

Applications of embedded system• Pen drives • Hard disk• Mouse • Calculators, electronics welding machine• Cell phones • Security system• Alarm system• Digital camera• Environment monitoring systems

Microcontroller A Microcontroller is a programmable digital processor with

necessary peripherals. Both microcontrollers and microprocessors are complex sequential digital circuits meant to carry out job according to the program / instructions. Sometimes analog input/output interface makes a part of microcontroller circuit of mixed mode (both analog and digital nature).

Types: (a) RISC microcontroller

(b) CISC microcontroller

we have used ATmega16 in training

Features of Modern Microcontrollers

• Built‐in Monitor Program • Built‐in Program Memory • Interrupts • Analog I/O • Serial I/O • Facility to Interface External Memory • Timers

Pin diagram of ATmega16

Features of ATMEGA16

• It is a 40 pin Ic• Advanced RISC Architecture • 16K Bytes of In‐System Self‐Programmable Flash • 512 Bytes EEPROM • 1K Byte Internal SRAM • 32 Programmable I/O Lines • In‐System Programming by On‐chip Boot Program

Programming

Programmer basically consists of two parts:

• Software (to open .hex file on your computer)

• Hardware (to connect microcontroller

Hardware depends on the communication port you are using on the computer (Serial, Parallel or USB).

There are 2 good software which support this hardware and can communicate with micro controller using this circuit. They are,

• Pony Prog

• At‐Prog

Serial Programmer's Circuit (Hardware)

At-Prog(software)

USB Programmer

Code Vision AVR (CVAVR)

Atmel Microcontrollers are very famous as they are very easy to use. First of all we need an easy IDE (Integrated Development Environment) for developing code. We used CVAVR (Code Vision AVR)

It has limitation of code size. It works on computers with Windows platform that is

Windows XP & Vista.

Code Vision AVR (CVAVR)

Code Vision AVR (CVAVR)

Code Vision AVR (CVAVR)

Code Vision AVR (CVAVR)

Code Vision AVR (CVAVR)

Code Vision AVR (CVAVR)

I/O functions Register

Input Output functions are set by Three Registers for each PORT.

DDRX ‐‐‐‐> Sets whether a pin is Input or Output of Port X.

PORTX ‐‐‐> Sets the Output Value of Port X.

PINX ‐‐‐‐‐> Reads the Value of Port X.

LCD & LED

LCD vs. LED

• Since Timer works independently of CPU it can be used to measure time accurately.

• As we know a timer is an 8 bit register that keeps on increasing its value, so one of the basic conditions is the situation when timer register OVERFLOWS i.e. it has counted up to its maximum value (255 for 8 BIT timers) and rolled back to 0. In this situation timer can issue an interrupt and we must write an Interrupt Service Routine (ISR) to handle the event.

Timer

Atmega 16 has following timers:-

Timer 0 - It is an 8-bit timer and for this pin no. 4 (PB3) is used.

Timer 1 - It is 16 –bit timer, It has two types OC1A(8-bit) at pin no 19 and OC1B(8-bit) at pin no 18.

Timer 2 - It is also an 8-bit timer and pin no 21 (OC2) is used for this.

Timers in Atmega16

There are four modes of timers, are as: Normal mode CTC mode Fast PWM mode Phase correct PWM mode

Modes of Timers

Normal Mode

CTC Mode

Fast PWM Mode

Phase Correct PWM Mode

SETTING UP TIMERS IN CVAVR

SETTING UP TIMERS IN CVAVR

SETTING UP TIMERS IN CVAVR

SETTING UP TIMERS IN CVAVR

• Serial Peripheral Interface Bus or SPI bus is a synchronous serial data link used to communicate between two or more microcontroller and devices supporting SPI mode data transfer.

• In this mode, devices communicate in master/slave mode where the master device initiates the dataframe. Multiple slave devices are allowed with individual slave select (chip select) lines.

SPI: Serial Peripheral Interface

• SPI communication protocol consists of following pins:-–MOSI : Master Out Slave In (Tx for Master and

Rx for Slave)–MISO : Master In Slave Out (Rx for Master Tx for

Slave)– SCK : Serial Clock (Clock line)– SS : Slave Select (To select Slave chip) (if

given 0 device acts as slave)

SPI: Serial Peripheral Interface

MOSI:-Channel where the master sends the data to the slave and the slave receives it.

MISO:-Channel where the slave sends the data and the master receives it.

SPI: Serial Peripheral Interface

SCK:-Clock is send by the master.

SS:-Slave select when the master wants to send data to a particular slave it makes its SS pin low, sends the data and then again makes it high.

SPI: Serial Peripheral Interface

In the UART protocol, the transmitter and the receiver do not share a clock signal. That is, a clock signal does not emanate from one UART transmitter to the other UART receiver. Due to this reason the protocol is said to be asynchronous

UART

• Serial Port is used for communication between the uC and the computer.

• A serial port has 9 pins.• For laptop, most probably there wont be a serial port.

In such case, we use a USB to serial Converter.• For transmitting one byte of data, the serial port will

transmit 8 bits as one bit at a time.

Serial Port of Computer

Serial Port of Computer

• Pin 3 is the Transmit (TX) pin, pin 2 is the Receive (RX) pin and pin 5 is Ground pin.

• Other pins are used for controlling data communication in case of a modem.

• For the purpose of data transmission, only the pins 3 and 5 are required.

Serial Port of Computer

MotorsDevice used to convert electrical energy into mechanical energy is called a motor.Some Motors used in embedded systems and robotics are described as below:

i. Stepper motors

ii. Servo motors

iii. Geared DC Motors

Motors

We used Gear motors during Training.

• Gear motors are motors with an integrated gearbox.

• Geared motors have a variety of applications. Some of its uses are as in wheelchairs, stair wheels etc.

H- Bridge

Motor Driver ICs: Pin Diagram

Sensors

A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument.

We can use different types of sensor like,

1. Temperature sensor: We use LM35 IC as temperature sensor.

Sensors 2. Light Dependent Resistor (LDR): LDR is basically a resistor whose resistance varies

with intensity of light. More intensity less its resistance (i.e, in black it offers high resistance and in white it offers less resistance).

Sensors

TSOP:TSOP 1738 Sensor is a digital IR Sensor; It is logic 1 (+5V) when IR below a threshold is falling on it and logic 0 (0V) when it receives IR above threshold.

It does not respond to any stray IR, it only responds to IR falling on it at a pulse rate of 38 KHz.

Sensors IR- Sensor:

Sensors

IR-Sensor:

In this we use three main components IR-LED, Photo diode & LM358 IC.

From any “non black body” obstacle IR reflects and falls on photo diode.

Hence Photo diode become forward bias, and it turn on the IC LM358 that gives the output.