MICROCONTROLLER AND INTERFACING Presented by: Shefali Jethva ( ) Shivali Panchal ( ) Komal Soni ( ) Roll no. :- 14EC308 14EC309 14EC310 Discipline: EC 5 th Sem. Guided by: Prof. Isha Gautam prof. Satish Bhati

CONTENTS I2C PROTOCOL SPI PROTOCOL AND DISPLAY INTERFACING PWM PROGRAMMING AND DC MOTOR CONTROL

What is I2C?  Shorthand for an “ Inter-Integrated Circuit” bus.  Developed by Philips Semiconductor for TV sets in the 1980’s.  I2c devices includes EPROMs, thermal Sensors & real time clock.  Used as a control interface to signal processing devices that have separate data interface.  Eg. Rf tuner, video decoder & encoder & audio processor.  Limited to about 10 feet for moderate speed.

I2C PROTOCOL:  Master sends start condition(s) & controls the clock signal.  Controls the clock signal.  Master sends a unique 7-bits slave devices address.  Master sends read/write bit (R/W)-0-slave receive,1-slave transmit.  Slave with matching 7-bit device address always sends acknowledge bit(ACK).  Transmitter (slave or master) transmit 1 byte of the data.

I2C FEATURE:  “ Clock Stretching”-When the receive needs more time to process a bit, it can pull SCl low to keep it from going high a bit longer. This technique is called Clock stretching. On SDL low, the transmitter can send its next data value, but this slave is ready to release SCL to go high.  “General Call” broadcast- address every device on the bus.  10-bit extended addressing for new designs 7-bit address a exhausted.

SPI Configuration: Primarily used for serial communication between a host processor and peripherals. Can also connect 2 processors via SPI SPI works in a master slave configuration with the master being the host microcontroller for example and the slave being the peripheral

SPI Operation: For SPI, there are Serial Clocks (SCLK), Chip Select lines (CS), Serial Data In (SDI) and Serial Data Out( SDO) There is only one master, there number of slaves depends on the number of chip select lines of the master. Synchronous operation, latch on rising or falling edge of clock, SDI on rising edge, SDO on falling edge Operates in 1 to 2 MHz range. Master sends out clocks and chip selects.

Advantages of SPI: It’s faster than asynchronous serial The receive hardware can be a simple shift register It supports multiple slaves Disadvantages of SPI: It requires more signal lines than other communications methods The communications must be well-defined in advance The master must control all communications It usually requires separate SS lines to each slave, which can be problematic if numerous slaves are needed.

PWM PROGRAMMING AND DC MOTOR CONTROL  WHAT IS PWM ? PWM is a way of digitally encoding analog signal levels. Through the use of high-resolution counters, the duty cycle of a square wave is modulated to encode a specific analog signal level. The PWM signal is digital because, at any given instant of time, the full DC supply is either fully on or fully off. The voltage or current source is supplied to the analog load by means of a repeating series of on and off pulses.

INTERFACING OF AVR AND DC MOTOR

PROGRAM: 1 A switch is connected to PA 7. perform following: (a) PA7=0, motor moves clock wise (b) PA7=1, motor moves anti-clock wise.INCLUDE "M32DEF.INC" SBI DDRC,0 // MAKE PC0 AS AN OUTPUT (SW-1) SBI DDRC,1 // MAKE PC1 AS AN OUTPUT (SW-2) SBI DDRC,2 // MAKE PC2 AS AN OUTPUT (SW-3) SBI DDRC,3 // MAKE PC3 AS AN OUTPUT (SW-4) CBI DDRA,7 // MAKE PA7 AS AN INPUT CLOCKWISE: SBIS PINA,7 // SKIP NEXT IF PA7 IS SET RJMP CLOCKWISE // IF PA7=0 GO TO CLOCKWISE CBI DDRC,1 // SW 2=0 CBI DDRC,2 // SW 3=0 SBI DDRC,0 // SW 1=1 SBI DDRC,3 // SW 4=1 JMP MONITOR

ANTI-CLOCKWISE: CBI DDRC,0 // SW 1=0 CBI DDRC,3 // SW 4=0 SBI DDRC,1 // SW 2=1 SBI DDRC,2 // SW 3=1 JMP MONITOR OUTPUT: