ESSENTIALS OF MOTORSAND MOTOR DRIVER

INTERFACING PROXIMITY SENSOR WITH MOTOR

MOTOR : WHAT IS IT? 

Electrical Motors are continuous actuators that convert electrical energy into mechanical energy in the form of a continuous angular rotation that can be used to rotate pumps, fans, compressors, wheels, etc. 

MOTORS EVERYWHERE!

Refrigerator - Two or three in fact: one for the compressor, one for the fan inside the refrigeratorTape player in the answering machineVacuum cleaner Electric drillFanElectric toothbrushHair dryerPower seats (up to seven motors per seat)Windshield wipers

MOTOR : TYPES

If you plan to get involved in robotics, you will need to familiarize yourself with the many types of motors available. 

BRUSHED DC MOTOR

MOTOR : TYPES

 

GEARED DC MOTORDC motors are often coupled with gears which provide greater torque, but reducing speed.

MOTOR : TYPES

 

BRUSHLESS DC MOTOR

SERVO MOTOR

STEPPER MOTOR

LINEAR DC MOTOR

MOTOR : INPUTS 

INPUT AT A

INPUT AT B

OUTPUT

1 0 ROTATES CLOCKWISE

0 1 ROTATES ANTICLOCKWISE

1 1 STOPS

0 0 STOPS

MOTOR DRIVER

 A motor driver is an electronic device that acts as an intermediate device between a microcontroller, a power supply or batteries, and the motors.

Why do we not connect our motor directly to the mcu?The motor draws very high current much higher than the operating current of the mcu.

Thus, the microcontroller and the motor driver have to work together in order to make the motors move appropriately.

Integrated Circuits (IC)

An integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small plate or chip of semiconductor material, normally silicon.

MOTOR DRIVER :DC Motor Control: 

Nominal voltage.: DC motor controllers tend to offer a voltage range. For example, if your motor operates at 3V nominal, you should not select a motor controller that can only control a motor between 6V and 9V

Continuous current: You need to find a motor controller that will provide current equal to or above the motor’s continuous current consumption under load. Should you choose a 5A motor controller for a 3A motor, the motors will only take as much current as they require. On the other hand, a 5A motors is likely to burn a 3A motor controller.

Using H-bridge circuit, you can supply current in two directions.Thats it. Lets say you have a DC motor, as in the diagram below:If you Close both S1 and S2?Close S3 and S4. Close switches S1 and S4Close S3 and S2

Direction of rotation in last two cases?

This is exactly whats needed in most robotics projects using differential drive wheels. But having physical switches would be very inconvenient. So an electronically controlled switch: a transistor is used.

WORKING: L293D AN H-BRIDGE

Vcc1  : logical voltage supply for a 1

Vcc 2 is the actual voltage that needs to be output

GND represents grounds. These are needed for the multiple solid state switches that are burned into the IC.

ENABLE pins enable/disable the corresponding sides.

PIN DIAGRAM

HOW TO SET-UP CONNECTIONS

HOW TO MAKE IT WORK

IF you put a logical 1 into INPUT1 Then the chip will simply put Vs volts into OUTPUT1.

Similarly, if you put a logical 0 into INPUT1, the chip will ground OUTPUT1.That is Putting a logical 1 into INPUTx will put Vs volts in OUTPUTx. And putting a 0 grounds the corresponding pin.

One word of caution though. You can use a maximum of 0.5A of current over each OUTPUTx pin. Use a bit more and you risk fusing the chip.

INTRODUCTION TO MICROCONTROLLERS

ROBOTICS AND MACHINE INTELLIGENCE

NIT TRICHY

What is a Microcontroller?

Mcu is similar to your home computer.

At the same time, it is different from your home computer. how?

The computing power is much scaled down in your microcontroller compared to your laptop.

Microcontroller vs. Microprocessor

Used to execute big and generic applications

Very high processor speeds of the order of GHz (many times faster)

It is a stand alone device. RAM, ROM, I/O peripherals and Timers have to be interfaced separately

Suited for applications where time and accuracy are critical (Personal Computers)

Used to execute a single task with one application

Much lower processing speeds ranging from as low as 4kHz to a few MHz

The CPU, RAM, ROM, I/O Peripherals and Timers are all on the same chip

Suited for applications where cost, power and space are critical (Embedded Systems)

Microprocessor(Laptops, Desktops etc.)

Microcontroller(Atmega8)

Features of a Microcontroller Architecture : Harvard or Von

Neumann; RISC or CISC Speeds of up to 16 MIPS ISP Flash Memory, EEPROM,

SRAM General Purpose I/O Registers

(GPIO) Internal Calibrated Oscillator

and external clocking options 8 bit and 16 bit Timer/Counters ADC and PWM Features External and Internal Interrupt

sources Programmable Watchdog Timers USART, SPI and I2C Interfaces PDIP, TQFP or QFN Packaging

Block Diagram

Microcontroller Families

Examples of the different series of microcontrollers are: 8051(At89s52) AVR (Atmega8/16) PIC (PIC10F) ARM (LPC2148) MSP (MSP430)

WHY AVR? Advanced RISC Architecture In System Programmability (ISP) Mode Inbuilt 10 bit ADC Very low cost microcontrollers are available Supported by the GNU Compiler Collection (GCC) Three sub families : TinyAVR, MegaAVR, XMegaAVR

ATMEGA 8 Pin Diagram

Features of an ATMEGA 8

Up to 16MIPS Throughput at 16MHz 8Kbytes of In-System Self-programmable

Flash program memory Data retention: 20 years at 85°C/100 years

at 25°C In-System Programming by On-chip Boot

Program True Read-While-Write Operation 3 I/O Ports Comes in a 28 pin package.

Description of each pinPin 1 (Reset): When this pin is pulled low microcontroller get reset. Reset means code start executing from the beginning. In normal mode of execution it should have at least 2.7V. Thus

it is connected to +5 volts through 10k ohm resistance to make sure voltage on reset pin should be above 2.7 for proper execution of code.

Pin 7 and 20 (Vcc): Pin 7 and 20 are connected to Power supply. (2.7 to 5.5 volt)

Pin 8 and 22 (Ground): Pin 8 and 22 are connected to Ground. Ground must be

common to for the entire circuit.

Input and Output Ports In ATmega8 we have three I/O (input/output) ports, Port B,

Port C, Port D. Any pin can be configured as input or output pin by software.

I/O in AVR

Input/output happens through the specified pins in AVR. A group (generally consisting of 8 pins) is called a PORT. Each port has associated registers with it that help in acquiring/transmitting the data from/to the pins and also configuring them.

Headers and registers for I/O The header “avr/io.h” is the library in

which all the I/O commands are defined. Syntax: #include<avr/io.h> Every port in AVR (which 8 bit and hence

has 8 pins) will have three I/O registers associated with it:

DDRx – Data Direction Register PORTx – Output Operation PINx – Input Operation

Configuring I/O pins

The value of DDR that is set by the programmer is what decides whether the particular pin in the MCU will behave as an input or as an output pin.

If a specific bit of the DDRx is set to 1 then it behaves as an output pin while the value 0 makes it behave as an input pin. For example:

DDRD = 0b00001111;The above line configures the lower nibble of PORTD to output and the higher nibble to input.

Taking inputs – The PINx Register

PINx (Port IN) is used to read data from port pins. In order to read the data from port pin, first you have to

change port’s data direction to input. If port is made output, then reading PINx register will give

you data that has been output on port pins. This register cannot be used to output data on to the pins To read data from port A. DDRA = 0x00; //Set port a as input x = PINA; //Read contents of port a

The above code will store the input value into the variable ‘x’.

The PORTx register

It is mainly used to output data. To output 0xFF data on port B:DDRB = 0b11111111; //set as output

PORTB = 0b11111111; //write data on port It is also used to activate/deactivate the

pull up resistors when port is configured as input.

The value 1 actiavtes the pull up resistors while 0 will deactivate them.

THANK YOU

THE END