Essentials of motors and motor driver

1. Essentials of motorsand motor driver INTERFACING PROXIMITY SENSOR WITH MOTOR

2. 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. 

3. Refrigerator - Two or three in fact: one for the compressor, one for the fan inside the refrigerator Tape player in the answering machine Vacuum cleaner Electric drill Fan Electric toothbrush Hair dryer Power seats (up to seven motors per seat) Windshield wipers MotoRS EVERYWHERE!

4. 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

5. GEARED DC MOTOR DC motors are often coupled with gears which provide greater torque, but reducing speed. Motor : types

6. SERVO MOTOR BRUSHLESS DC MOTOR LINEAR DC MOTOR Motor : types STEPPER MOTOR

7. Motor : INPUTS

8. 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. Motor driver

9. 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.

10. 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. Motor driver :

11. Using H-bridge circuit, you can supply current in two directions.Thatsit. 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 S4 Close 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

12. Vcc1 :logical voltage supply for a 1 Vcc 2is the actual voltage that needs to be output GNDrepresents grounds. These are needed for the multiple solid state switches that are burned into the IC. ENABLEpins enable/disable the corresponding sides. Pin diagram

13. howto set-up connections

14. 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. howto make it work

15. INTRODUCTION TO MICROCONTROLLERS ROBOTICS AND MACHINE INTELLIGENCE NIT TRICHY

16. 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.

17. Microcontroller vs. Microprocessor Microprocessor(Laptops, Desktops etc.) Microcontroller(Atmega8) • 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)

18. 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

19. 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

20. ATMEGA 8 Pin Diagram

21. 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.

22. Description of each pin Pin 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.

23. 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.

24. 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

25. 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 PORTDto output and the higher nibble to input.

26. 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’.

27. 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.

28. THANK YOU THE END