intro_mcu.pdf
- 2. Micro-Controller • A single chip Computer (to some extent) • Has CPU 1. RAM 2. EEPROM 3. I/O in form of pins 4. Peripherals (Timer , Communication modes , ADC etc)
- 3. Flash Back (Takneek) • Line Following Robots • Wireless keyboards • They were made using Microcontrollers
- 4. • Suppose we want to make a Line following Robot • What do we do ? • Use a computer with 2.4Ghz Intel core I7 with 4 Gb RAM , 500 Gb Hard disk , 1 Gb Graphics Card ??
- 5. Why not a Computer ? • PC is a general purpose computer. • Can run thousand of softwares • Microsoft ppt in which you are seeing this presentation • Games (NFS , AOE , Call of Duty) • Highly expensive
- 6. Why MCU • Small reflected by the word “MICRO” • Inexpensive • Ideal for doing repetitive tasks • Easy to use • Highly Efficient and fast
- 7. Selecting a MCU • Two family of MCU extremely popular a) AVR b) PIC • We use AVR series of MCU from Atmel • The instructions are fed once in the form of a Hex file
- 8. Tools Required -> CVAVR
- 9. Compiler -> CVAVR • The code is written in C language so we need to convert it into the format that Atmega understands
- 10. Transfer code to Atmega AVR Studio
- 11. Avr Programmer
- 12. • So we need two softwares overall a) CVAVR –> Editor and Compiler b) Avr Studio –> Transfer Code to Atmega
- 13. Atmega 16
- 14. Basics of C language • If else block • If(condition) { … … } else { … … }
- 15. While & For • While (conditon) { … ... } • for(initialisation; condition; increment) { … … }
- 17. •Lets Begin by blinking a simple LED
- 18. Circuit Diagram
- 19. Getting Started with CVAVR
- 21. Open CVAVR
- 22. Go to File
- 23. Click on New
- 24. Select Project- > Click OK
- 25. Click YES
- 26. Select Chip
- 28. • Atmega has total of 40 pins out of which 32 pins can be used as Input or Output • These 32 pins are divided into 4 groups of 8 pins PORTA, PORTB , PORTC , PORTD
- 29. Data Direction register (DDR) • This sets direction for all pins (32) • Direction for these pins can be Input or Output • To blink an LED we need to set pin as “OUTPUT” but “HOW“ ? • DDRA = 0b00000001 ; • DDRA = 0x01 ; • 1 Stands for Output & 0 stands for Input
- 31. What Next ? • We have set the Pin as Output • What else do we need to light the LED ?? • Supply of 5 Volts !!! This is given by PORT Register
- 32. PORT Register • Only after you have set the Pin to Output you can control them through this Register • It is a 8 bit register . It corresponds to the pin in same manner as that of DDR Register • Used to set output value ( 0 or 1 ) only if the corresponding Pin has been set as output by DDR Register • PORTA= 0b 00000001; or • PORTA= 0x01 ; • 1 stands for 5V • 0 stands for 0V L L L L L L L H MSB LSB
- 33. Simple Questions • DDRA= 0b 00101100 • DDRD = 0xf4 • DDRC = 0b 01111110 • DDRB = 0x3b Assume all 32 pins set as output • PORTA = 0b00001100; • PORTD = 0b11110000; • PORTB.4=1; • PORTC.2=1;
- 34. Setting I/O
- 35. Go to Ports
- 36. • Click on In to make that pin Output • Can do so for all four ports
- 37. Click on File
- 38. Generate Save and Exit
- 39. Enter name (3 times)
- 40. Where is the code stored ?
- 41. Then Click Save
- 42. Name of Project & Location
- 43. Writing the Code
- 44. • NOTE : We write our code in While block • While (1) { PORTA.1=1; // sets the Pin to 5 volts PORTA.1=0; // sets the Pin to 0 volts } • This makes the LED to blink but we cannot see blinking !!!
- 45. • This is because Atmega runs at a frequency of 8000000 Hz • We need to introduce delay so as to see blinking • Use header file delay.h • Function to be used delay_ms(time in millis); While (1) { delay_ms(1000); PORTA.1=1; delay_ms(1000); PORTA.1=0; }
- 46. How to compile • Code is written in C language but Atmega understands Hex file so we need to convert the C file to Hex file
- 47. Compiling
- 48. Make the Project
- 49. Check for errors
- 50. Hex File • You can find the Hex file in Bin folder or the EXE folder of the directory where You installed CVAVR
- 51. • So we Have our Code ready • Feed this code to Atmega using Programmer (we will see this in workshop ) • Lets see the code in action
- 53. Lets add an Input • Most Common Input Button • Since we have already made A0 as Input we connect a button to that pin • If button is pressed light the LED else turn it off • First draw the Circuit Diagram
- 54. Circuit Diagram
- 55. • Never leave any Input pin unconnected / floating at any point of time while your circuit is working • In Last Circuit A0 is floating when button is not pressed so our Circuit Diagram is wrong
- 56. • What is the Voltage at the Floating PIN ? • Not 5 V • Not 0V • Its UNDEFINED • So never leave an input pin unconnected • Use the Concept of Pull up / Pull down
- 57. • In Layman terms • PULL DOWN : Gives 0V when unconnected • PULL UP : Gives 5V when unconnected • Connect the PIN to Ground through a resistance for pulling down • Connect the PIN to 5V through a resistance for Pulling up
- 59. PIN Register • It is a 8 bit register . It corresponds to the pin in same manner as that of DDR Register • It is used to read voltage at a pin • To be used only after the pin has been set as input by DDR register
- 60. Using Pin Register int a; // Define the variable a to store the value of voltage a=PINA.0; // read value at pin A.0 (make sure it is input) If (a==1) // if voltage is 5V { PORTA.1=1; // Light the LED } else { PORTA.1=0; // Turn off the LED }
- 61. Code in Action
- 62. Thank You