2. **** A MICROCONTROLLER IS A SINGLE CHIP
MICROPROCESSOR SYSTEM WHICH CONSISTS OF
CPU, DATA AND PROGRAM MEMORY, SERIAL
AND PARALLEL I/O PORTS, TIMERS AND
EXTERNAL AS WELL AS INTERNAL INTERRUPTS.
** IT CAN ALSO BE CALLED AS A ENTIRE
COMPUTER MANUFACTURED ON A SINGLE
CHIP.
3. Microcontroller 8051 was first developed by
INTEL, for use in embedded systems.
it consisted of standard on chip peripherals i.e.
timers, counters, 4k bytes of on chip program
memory and 128 bytes of data memory.
It has separate spaces for program memory and
data memory.
It has 128 byte of data memory that are
accessible directly by its instructions.
4. 8051 CENTRAL PROCESSING UNITS
4k *8 ROM
128*8 RAM
Three 16 bit counters/timers.
Full duplex serial channels
Boolean processor full static operation
MEMORY ADDRESSING CAPABILITY
64k ROM and 64k RAM
5. POWER CONTROL MODES:-
- idle mode
- power-down mode
CMOS and TTL compatible
Frequency range of 0 to 33 MHz
4 level priority interrupts
6 interrupt services
Four 8 bit i/o ports.
6.
7. ACCUMULATOR(ACC):- it is used for data
transfer and arithmetic operations. After any
operation result is stored in ACC and can be
accessed through its SFR address of 0E0H.
B REGISTER:- it is used to store the upper 8 bit
result of multiplication and divisions. It is used
as temporary register and can be accessed
through its SFR address of 0F0H.
8. CY AC FO RS1 RS0 OV P
PROGRAM STATUS WORD(PSW):- This
special function register and consists of
different status bits that reflect the current state
of microcontroller. It contains carry (CY), the
auxiliary carry(AC), the two registors bank
select bits(RS1 and RS0), the overflow flag(OV),
a parity bit(P), and two user defined status
flags.
9. STACK POINTER(SP):- This is an 8 bit register. SP
is incremented before the data is stored onto the
stack using PUSH/CALL instructions execution.
During PUSH, first SP is incremented and then
copy the data. In the POP operation, initially copy
the data and then decrement the SP.
DATA POINTER(DTPR):- DTPR is a 16 bit
register. It consists of higher byte (DPH) and a
lower byte (DPL). DPTR is very useful for string
operations and look up table operations. With a 16
bit DPTR, a maximum of 64K of off chip data
memory and 64k of off chip memory can be
addressed.
10. PORT0, PORT1, PORT2, PORT3 LATCHES AND
DRIVERS:- Each latch and corresponding
drivers of port 0-3 is allotted to the
corresponding on chip I/O port.
