Transcript MICROCONTROLLER AND INTERFACING

MICROCONTROLLER AND INTERFACING
Presented by: Shefali Jethva (140803111008)
Shivali Panchal (140803111009)
Komal Soni
(140803111010)
Roll no. :- 14EC308
14EC309
14EC310
Discipline: EC 5th 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
SBI DDRC,1
SBI DDRC,2
SBI DDRC,3
CBI DDRA,7
CLOCKWISE: SBIS PINA,7
RJMP CLOCKWISE
CBI DDRC,1
CBI DDRC,2
SBI DDRC,0
SBI DDRC,3
JMP MONITOR
// MAKE PC0 AS AN OUTPUT (SW-1)
// MAKE PC1 AS AN OUTPUT (SW-2)
// MAKE PC2 AS AN OUTPUT (SW-3)
// MAKE PC3 AS AN OUTPUT (SW-4)
//
//
//
//
// MAKE PA7 AS AN INPUT
// SKIP NEXT IF PA7 IS SET
// IF PA7=0 GO TO CLOCKWISE
SW 2=0
SW 3=0
SW 1=1
SW 4=1
ANTI-CLOCKWISE: CBI DDRC,0
CBI DDRC,3
SBI DDRC,1
SBI DDRC,2
JMP MONITOR
• OUTPUT:
//
//
//
//
SW 1=0
SW 4=0
SW 2=1
SW 3=1