Download ECP2042 Microprocessor and Interfacing

Registers
Control & Status
Registers
User-Visible
Registers
Program Counter
General-Purpose Reg.
Instruction Register
Address Register
...
Data Register
...
Flag Register
ECP2036 Microprocessor and Interfacing
To hold the memory address of the
next instruction to be executed
Control & Status
Registers
User-Visible
Registers
Program Counter
General-Purpose Reg.
Instruction Register
Address Register
...
...
Data Register
Default value at power on/reset:
PC = 0000H or FFFFH (or other address
predetermined by the manufacturer)
ECP2036 Microprocessor and Interfacing
To hold the instruction
memory
Control & Status fetched from external
User-Visible
Registers
Registers
Program Counter
General-Purpose Reg.
Instruction Register
Address Register
...
Data Register
...
Flag Register
ECP2036 Microprocessor and Interfacing
Can be assigned to a variety
of functions
by programmer
Control
& Status
Registers
User-Visible
Registers
Program Counter
General-Purpose Reg.
Instruction Register
Address Register
...
Data Register
...
Flag Register
ECP2036 Microprocessor and Interfacing
To hold the address of next
Control
Status to be addressed User-Visible
memory&location
Registers
Registers
Program Counter
General-Purpose Reg.
Instruction Register
Address Register
...
Data Register
...
Flag Register
ECP2036 Microprocessor and Interfacing
To hold the data
fetched from memory
User-Visible
Registers
Program Counter
General-Purpose Reg.
Instruction Register
Address Register
...
Data Register
...
Flag Register
ECP2036 Microprocessor and Interfacing
Condition-code register that contains
a number of flag bits.
Control & Status
Registers
Each flag bit is either set (“1”) or reset (“0”)
by the result of an arithmetic or logical
General-Purpose Reg.
instruction that has just been executed
Instruction Register
Address Register
...
Data Register
...
Flag Register
ECP2036 Microprocessor and Interfacing
Memory
Memory Address-1  Memory Location-1
Memory Address-2  Memory Location-2
1 2 3 4 5 6 7 8
1 word = 8-bit data
(for 8051)
Memory Address-n  Memory Location-n
ECP2036 Microprocessor and Interfacing
Bus System (I)
Address Bus
These are the wires that carry the CPU generated address
signals out to memory and to I/O devices.
The address signals only travel outwards from the CPU
(unidirectional).
The number of address lines that a microprocessor has
determines the size of the memory space that it can
access.
ECP2036 Microprocessor and Interfacing
Memory Size
No of Add. lines
Size of memory space
8
28 = 256
16
216 = 65 536 = 64 K
20
220 = 1 048 576 = 1 M
24
224 = 16 777 216 = 16 M
32
232 = 4 294 967 296 = 4 G
ECP2036 Microprocessor and Interfacing
Bus System (II)
Data Bus
These are the data signals that travel out of and
into the P (bi-directional).
The number of wires in the data bus depends on
the word size that the P operates with.
An 8-bit P will have a data bus consisting of 8
wires and a 32-bit P will have a data bus with 32
wires.
ECP2036 Microprocessor and Interfacing
Bus System (III)
Control Bus
The control bus consists of wires, some of which
carry signals from the CPU to external devices,
while others carry signals from external devices to
the CPU.
The number of wires present in the control bus
varies from one P to another.
Examples of control bus signals are READ/,
WAIT, READY, and HOLD.
ECP2036 Microprocessor and Interfacing
von Neumann Architecture
ALU
Main
Memory
CU
ECP2036 Microprocessor and Interfacing
I/O
Basic Instruction Cycle
PC = 0000H
Start
Fetch
Instruction
Fetch Cycle
Execute
Instruction
Execute Cycle
PC = PC + n
End
ECP2036 Microprocessor and Interfacing
Memory Read Operation - Step 1
The CPU sends out the control signals Memory
Request and Read to indicate that it wants to
read from memory
CPU
Read
Memory
Memory request
Data bus
Address bus
CPU places address (XXXX) of the
memory location on the address bus
ECP2036 Microprocessor and Interfacing
Memory Read Operation - Step 2
Accessed location at XXXX
CPU
Read
Memory
Memory request
Data bus
Address bus
Memory places data from the
accessed location onto the data bus
ECP2036 Microprocessor and Interfacing
Memory Read Operation - Step 3
The CPU removes the Memory Request
and Read signals
CPU
Read
Memory
Memory request
Register
Data bus
Address bus
CPU latches the data into a register
ECP2036 Microprocessor and Interfacing
Memory Write Operation - Step 1
The CPU sends out a Memory Request control
signal to indicate that it wants to perform a
memory operation
CPU
Memory
Memory request
Data bus
Address bus
CPU places address (YYYY) of the
memory location on the address bus
ECP2036 Microprocessor and Interfacing
Memory Write Operation - Step 2
The CPU sends out a Write control signal to
indicate that valid data is available on the data
bus
CPU
Write
Memory
Memory request
Register
Data bus
Address bus
CPU places the data from a register
onto the data bus
ECP2036 Microprocessor and Interfacing
Memory Write Operation - Step 3
The CPU removes the Write signal to complete
the memory write operation
CPU
Write
Memory
Memory request
Register
Data bus
Address bus
Memory copies the data bus into the
accessed location
ECP2036 Microprocessor and Interfacing
Accessed location
at YYYY
Assembly Language Program
An assembly language program is a program written
using labels and mnemonics, in which each statement
corresponds to a machine instruction.
; A test program
LOOP:
ORG
MOV
RL
MOV
JMP
END
0000H
A, #01H
A
P1, A
LOOP
; output to port 1
ECP2036 Microprocessor and Interfacing
Assembling A Source Program
An assembler is a program that translate an assembly
language program into a machine language program.
program.obj
program.src
asm51
program.lst
ECP2036 Microprocessor and Interfacing
Linking Object Files
A linker/locator is a program that combines relocatable
object programs (modules) and produces an absolute
object program that is executable by a computer.
program
File3.obj
File2.obj
File1.obj
RL51
program.m51
ECP2036 Microprocessor and Interfacing
BIN to HEX conversion
program.bin
OH
program.hex
Download to 8051
ECP2036 Microprocessor and Interfacing