07-06-2013, 12:54 PM
INTRODUCTION TO MICROCONTROLLERS
[attachment=54934]
Microprocessors Vs Microcontrollers:
The Microprocessors (Intel’s X86 family—8086, 80286, 80386, 80486, and Pentium OR Motorola’s
68000, 68010, 68020 etc) contains no RAM, no ROM, and no I/O ports on the chip itself.
When using these types of General purpose Microprocessors one must add RAM, ROM, I/O ports
And timers externally to make them functional. If the tasks demand the greater amount of RAM, ROM, and
I/O ports we need to go to these Microprocessors. It also leads to the systems bulkier and more expensive.
The case of Microcontrollers is entirely different. Microcontrollers has a CPU (microprocessor) in
Addition to a fixed amount of RAM, ROM, I/O ports, and a timer all are embedded together on a single chip.
Therefore the designer need not add any external memory, RAM, I/O ports and timer to it.
That is the main advantage of microcontrollers than microprocessors, which makes them ideal for
Many applications in where cost and space are critical. For this reason the microcontrollers are widely used
in many applications like TV remote control, Intercom, Telephones, security systems, Fax machines,
Cellular phones, Electronic Toys, Cameras, laser printers, Paging, Instrumentation, Keyless entry etc.
MICROCONTROLLER AT89S52:
The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in
system Programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile
Memory technology and is compatible with the indus-try-standard 80C51 instruction set and pin out.
The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional
Nonvolatile memory pro-grammar. By combining a versatile 8-bit CPU with in-system programmable Flash
on a monolithic chip, the Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible and
Cost-effective solution to many embedded control applications.
The AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O
lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level interrupt
Architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is
designed with static logic for operation down to zero frequency and supports two software selectable power
Saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and
Interrupt system to continue functioning. The Power-down mode saves the RAM con-tents but freezes the
Oscillator, disabling all other chip functions until the next interrupt or hardware reset.
MCS-51 devices have a separate address space for Program and Data Memory. Up to 64K bytes
Each of external Program and Data Memory can be addressed.
The WDT is intended as a recovery method in situations where the CPU may be subjected to
Software upsets. The WDT consists of a 14-bit counter and the Watchdog Timer Reset (WDTRST) SFR.
The WDT is defaulted to disable from exiting reset. To enable the WDT, a user must write 01EH and 0E1H
in sequence to the WDTRST register (SFR location 0A6H). When the WDT is enabled, it will increment
Every machine cycle while the oscillator is running. The WDT timeout period is dependent on the external
Clock frequency. There is no way to disable the WDT except through reset (either hardware reset or WDT
Overflow reset). When WDT over-flows, it will drive an output RESET HIGH pulse at the RST pin.
[attachment=54934]
Microprocessors Vs Microcontrollers:
The Microprocessors (Intel’s X86 family—8086, 80286, 80386, 80486, and Pentium OR Motorola’s
68000, 68010, 68020 etc) contains no RAM, no ROM, and no I/O ports on the chip itself.
When using these types of General purpose Microprocessors one must add RAM, ROM, I/O ports
And timers externally to make them functional. If the tasks demand the greater amount of RAM, ROM, and
I/O ports we need to go to these Microprocessors. It also leads to the systems bulkier and more expensive.
The case of Microcontrollers is entirely different. Microcontrollers has a CPU (microprocessor) in
Addition to a fixed amount of RAM, ROM, I/O ports, and a timer all are embedded together on a single chip.
Therefore the designer need not add any external memory, RAM, I/O ports and timer to it.
That is the main advantage of microcontrollers than microprocessors, which makes them ideal for
Many applications in where cost and space are critical. For this reason the microcontrollers are widely used
in many applications like TV remote control, Intercom, Telephones, security systems, Fax machines,
Cellular phones, Electronic Toys, Cameras, laser printers, Paging, Instrumentation, Keyless entry etc.
MICROCONTROLLER AT89S52:
The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in
system Programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile
Memory technology and is compatible with the indus-try-standard 80C51 instruction set and pin out.
The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional
Nonvolatile memory pro-grammar. By combining a versatile 8-bit CPU with in-system programmable Flash
on a monolithic chip, the Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible and
Cost-effective solution to many embedded control applications.
The AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O
lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level interrupt
Architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is
designed with static logic for operation down to zero frequency and supports two software selectable power
Saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and
Interrupt system to continue functioning. The Power-down mode saves the RAM con-tents but freezes the
Oscillator, disabling all other chip functions until the next interrupt or hardware reset.
MCS-51 devices have a separate address space for Program and Data Memory. Up to 64K bytes
Each of external Program and Data Memory can be addressed.
The WDT is intended as a recovery method in situations where the CPU may be subjected to
Software upsets. The WDT consists of a 14-bit counter and the Watchdog Timer Reset (WDTRST) SFR.
The WDT is defaulted to disable from exiting reset. To enable the WDT, a user must write 01EH and 0E1H
in sequence to the WDTRST register (SFR location 0A6H). When the WDT is enabled, it will increment
Every machine cycle while the oscillator is running. The WDT timeout period is dependent on the external
Clock frequency. There is no way to disable the WDT except through reset (either hardware reset or WDT
Overflow reset). When WDT over-flows, it will drive an output RESET HIGH pulse at the RST pin.