1 the 8051 microcontroller architecture a microcontroller (μc) is a single integrated circuit that...
TRANSCRIPT
1
The 8051 Microcontroller Architecture
• A microcontroller (μC) is a single integrated circuit that executes a user program for controlling some device.
• A microcontroller has a CPU in addition to a fixed amount of RAM, ROM, I/O ports, serial port, and a timer all on a single chip.
• An embedded system uses a microcontroller to do one task and one task only.
• Microcontrollers are found in devices such as microwave ovens, automobiles, keyboards, CD players, cell phones, security systems, electronic toys, garage door openers, answering machines, … etc.
2
Differences between Microprocessors and Microcontrollers
1. Microprocessors contain no ROM, no RAM, no I/O ports, while microcontrollers contain ROM, RAM, I/O ports, timers and other peripherals.
2. Microcontroller systems are cheaper and more cost effective.
3. The computing power of microprocessors is higher.
3
Factors Influencing the Selection of Microcontroller Chips
• Speed
• Packaging
• Power consumption
• Amount of RAM and ROM on-chip
• Number of I/O pins
• How easy to upgrade to higher performance versions
• Cost per unit
4
Commercial 8-bit Microcontrollers
1. Intel’s 8051 Family
2. Microchip’s PIC Family
3. Motorola’s 6811 Family
4. Zilog’s Z8 Family
8051 Family Manufacturers
• Intel (Original)
• Atmel
• Philips/Signetics
• AMD
• Infenion (Formally Siemens)
• Dallas Semiconductors
5
The 8051 Microcontroller
• 8-bit CPU
• 128B on-chip RAM
• 4KB on-chip ROM
• 2 Timers
• Four I/O Ports (Each 8-bits wide)
• One Serial Port
DIP PackageSMD
Package
6
8051 Pin Configuration
7
8051 Family Members
MicrocontrollerOn-chip ROMOn-chip RAMTimers
80514K ROM128 bytes2
80310128 bytes2
87514K EPROM128 bytes2
89514K Flash ROM128 bytes2
80528K ROM256 bytes3
80320256 bytes3
87528K EPROM256 bytes3
89528K Flash ROM256 bytes3
8
8051 IC Minimum Connections
1 Machine Cycle = 12 Clock Periods = 12/ fck
fck = Clock frequency (4MHz – 30MHz)
9
8051 Memory Architecture
• The 8051 microcontroller uses the Harvard Architecture
• In Harvard Model the program memory is separated from data memory
10
Memory Organization
Internal RAM Memory Map
Internal and External Memories
On-chip ROM Address Space
11
Code Memory
12
Memory Expansion
13
Special Function Registers (SFRs)
14
The 8051 Basic Registers
15
PSW Register (Flag Register)
16
8051 I/O Ports
• The 8051 contains 4 I/O Ports
• Each port has 8-lines
• Each port can be programmed for input or output of data
• Port 0 and Port 2 can be used data and address lines for external memory interfacing
• Port 3 has alternate functions for external connections
• Port 0 should be connected to pull-up resistors before using it for data input or output
• Port 1 is solely designed for I/O data exchange