introduction to microprocessors & microcontroller prepared by md. zakir hossain lecturer dept....
TRANSCRIPT
Introduction to Microprocessor’s & Microcontroller
Prepared byMd. Zakir Hossain
LecturerDept. of EEE, KUET
Contents
8085 Microprocessor Bus, CPU, Memory and I/O of 8085 μp The 8085 Bus Structure CPU Internal Structure Hardware Description of uPC-MICRO 8085 Keys and Key Functions 8086μp internal architecture Function of Keypad & Register ATmega8(L) microcontroller
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MICROPROCESSOR
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A microprocessor is a multipurpose, programmable, clock-driven, register based electronic device that reads binary instructions from a storage device called memory; accepts binary data as input and processes data according to those instructions, provides results as output.
Fig1. CPU internal structure of 8085 microprocessor
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The internal architecture of the 8085 CPU is capable of performing the following operations:
Store 8-bit data (Registers, Accumulator) Perform arithmetic and logic operations (ALU) Test for conditions (IF / THEN) Sequence the execution of instructions Store temporary data in RAM during execution the ALU includes a temporary register used for holding data temporarily during the
execution of the operation. This temporary register is not accessible by the programmer.
The 8-bit 8085 CPU (or MPU – Micro Processing Unit) communicates with the other units using a 16-bit address bus, an 8-bit data bus and a control bus.
Address Bus
The address bus has 8 signal lines A8 – A15 which are unidirectional. The other 8 address bits are multiplexed (time shared) with the 8 data bits. 16 address lines are capable of addressing a total of 216 = 65,536 (64k) memory
locations. Address locations: 0000 (hex) – FFFF (hex) Identify perifheral or memory locations
THE 8085 BUS STRUCTURE
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Fig2. The 8085 Bus structure
Data Bus Consists of 8 data lines: D0 – D7
Operates in bidirectional mode Data range: 00 (hex) – FF (hex) use for transferring data
Control Bus Consists of various lines carrying the control signals such as read / write enable, flag
bits.
THE 8085 BUS STRUCTURE
6Fig3. The 8085 programmable registers
The 8085 programmable registers
Registers Six general purpose 8-bit registers: B, C, D, E, H, L They can also be combined as register pairs to perform 16-bit operations: BC,
DE, HL Registers are programmable (data load, move, etc.)
Accumulator Single 8-bit register that is part of the ALU . Used for arithmetic / logic operations – the result is always stored in the
accumulator.
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Memory: Where instructions (programs) and data are stored
• Organized in arrays of locations (addresses), each storing one byte (8 bits) in general
• A read operation to a particular location always returns the last value stored in that location
I/O devices: Enable system to interact with the world
• Device interface• I/O registers are connected to external wires, device control logic, etc.• Reads may not return last value written• Writes may have side effects
The Program Counter (PC)I. is used to control the sequencing of the execution of instructions.II. always holds the address of the next instruction.III. since it holds an address, it must be 16 bits wide.
The Stack pointer is also a 16-bit register that is used to point into memory. this register points to in a special area called the stack. the stack is an area of memory used to hold data that will be retreived soon. the stack is usually accessed in a Last In First Out (LIFO) fashion.
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Flag Bits Indicate the result of condition tests. Carry, Zero, Sign, Parity, etc. Conditional operations (IF / THEN) are executed based on the condition of
these flag bits.
The Flags register
There is also the flags register whose bits are affected by the arithmetic & logic operations.S-sign flag
The sign flag is set if bit D7 of the accumulator is set after an arithmetic or logic operation.
Z-zero flagSet if the result of the ALU operation is 0. Otherwise is reset. This flag is affected by operations on the accumulator as well as other registers. (DCR B).
AC-Auxiliary CarryThis flag is set when a carry is generated from bit D3 and passed to D4 .
P-Parity flagAfter an ALU operation if the result has an even # of 1’s the p-flag is set. Otherwise it is cleared. So, the flag can be used to indicate even parity.
CY-carry flagAfter an operation, if the result in the accumulator is larger than 8 bits, the flip-flop that is used to indicate a carry, called the carry flag.
S Z AC P CY
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8085 Instruction Set
Data transfer operations
Between registers Between memory location and a register Direct write to a register / memory Between I/O device and accumulator
Arithmetic operations (ADD, SUB, INR, DCR) Logic operations Branching operations (JMP, CALL, RET)
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Hardware Description
uPC-MICRO 8085 system consists
1) crystal controlled oscillator2) buffers for address 3) data control signals4) two 8255 (Programmable Peripheral Interface)5) one 8279 (Programmable keyboard & display controller)6) one 8253 (Programmable interval timer)7) one 8259A (Programmable Interrupt Controller)8) One 8251A (Programmable Communication Interface) with
RS232C drivers & receivers.9) 8 digit seven segment display10) 32 keys with one RESET key in keyboard
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Memory decoding & addresses
System EPROM : 0000 to 0FFF (32K) RAM (CMOS) : 8000 to 9FFF (8K) (8000 to 97FF user RAM) (9800 to 9FFF system RAM)Expansion RAM : A000 to BFFF (8K) C000 to DFFF (8K)
I/O DECODING AND ADDRESSES
SL. No. Peripheral LSI Base port address in Hex
01. A8255 00
02. B8255 20
03. 8251A 10
04. 8253 30
05. 8257 08
06. 8259A 28
Software description
At power on or at manual RESET, the CPU starts execution. Before executing the main routine, the various peripherals, flags and parameters in RAM are initialized.
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Display interface
Once a data is written to 8279 display RAM, 8279 automatically refreshes the data on 8 digit 7 segment LED display. One can optionally connect a LCD module to the port lines of the connector provided and writing the necessary software.
Keyboard interface 16 keys are assigned for 16 hexadecimals
16 keys for executing different functions 1 key mounted on the motherboard
Serial interface
duplex serial communication interface use 8251A serial communication controller with RS232C drivers at its output & RS232C receivers at its input
Keys and Key Functions
1. RESET2. INC 3. STEP 4. BREAK 5. EXEC/GO 6. REG 7. HELP 8. MOVE 9. Single Star (*) 10. Double Star (**) 11. FILL 12. INS 13. DEL 14. OUTPUT 15. INPUT 16. DOWNLOAD 17. DEC
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Executing a program in uPC-MICRO 8085
Label MnemonicsOp-code Operand
Hex Code Memory address
START MVI A, ECH 3E, EC 8000-01
MVI B, F1H 06, F1 8002-03
MVI C, 00H 0E, 00 8004-05
ADD B 80 8006
JNC LOOP1 D2, 0B, 80 8007-09
INR C 0C 800A
LOOP1 STA 8090 32, 90, 80 800B-0D
MOV A, CSTA 8091
7932, 91, 80
800E800F-11
END HLT 76 8012
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Fig4. Pin layout of the 8085 and 8086 microprocessor
The 8085 and 8086 Microprocessors
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Features of 8086 μp
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tells the BIU where to fetch instructions or data from, decodes instructions and executes instructions
Has a 16 bit arithmetic logic unit Decode instructions and done internal operations
CPU is divided into BIU & EU
Execution Unit (EU)
FLAG Register
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
/ / / / O D I T S Z / A / P / C
Control Flags Trap flag (TF) >> used for single stepping through a program Interrupt flag (IF) >> used to allow or prohibit the interruption of a program Direction flag (DF) >> used with string instructions
Conditional Flags Carry Flag (CF), Parity Flag (PF), Auxiliary Carry Flag (AF), Sign Flag (SF) ,Zero Flag (ZF) & Overflow Flag (OF) >> will be set if the result of a signed operation is too large
8086ΜPU INTERNAL ARCHITECTURE
Fig5. General purpose registers18
General register a. Data register (AX (AL & AH), BX (BL & BH), CX (CL & CH), DX (DL & DH))
used to store data b. Pointer & Index register (16 bit)
Stack Pointer (SP) >> holds the 16 bit offset from the start of segment Base Pointer (BP) >> holds the 16 bit offset and used for temporary store of
data Source Index (SI) >> holds the 16 bit offset of data word in the data segment
Destination Index (DI) >> used to indirect addressing & operation and temporary store of data
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Bus Interface Unit (BIU)
handles all transfers of data & addresses on the buses for the execution unit
The Queue stores prefetched bytes in first-in-first out fashion for EU Fetching the next instructions when the current instruction executes is called pipelining
Extra Segment (ES)
Code Segment (CS)
Stack Segment (SS)
Data Segment (DS)
Instruction Pointer (IP)
used to hold the upper 16 bits of the starting addresses of four memory segments Segment address (3000H) --------------- 30000H Offset address (1234H) -------------- + 1234H Real address --------------------- 31234H
Fig6. Segment registers
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Introduction to the MTS-86C microprocessor
CPU or “brain” ROM has addresses F0000H through FFFFFH and non-volatile RAM has addresses 00000H through 10000H and volatile Keyboard/display interface ( an 8279 device) 24 Key Keyboard Display: LCD Expansion area (upper left-hand side) Prototyping area (left-hand side) Reset Volatile memory 16 of data line and 20 of address line
Function of Keypad
RESET, NMI, +, -, ., REG, :, “,”, EB/AX, ER/BX, GO/CX, ST/DX, IB/SP, OB/BP, MV/SI, EW/DI, IW/CS, OW/DS, SS, ES, IP, FL,
Memory
F8000H
FFFFFH
E0000H
F0000H
400H
10000H
0H
MONITOR PROGRAM ROM
Exercise Program ROM
USER MEMORY ROM, RAM
OPEN
User program RAM
INTERRUPT VECTOR TABLE RAM
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I/O PORT ADDRESS ASSIGNMENTS
Port address
Port function
FFFFHFFFDHFFFBHFFF9H
PPI-1 control word resisterPPI-1 C portPPI-1 B portPPI-1 A port
Parallel I/O No. 1
FFFEHFFFCHFFFAHFFF8H
PPI-1 control word resisterPPI-1 C portPPI-1 B portPPI-1 A port
Parallel I/O No. 2
FFF2HFFF0H
8251-1 command8251-1 data
RS232C PORT 1
FFFAHFFE8H
8279 Status or Command8279 Data
Keypad control
FFDEHFFDCHFFDAHFFD8H
8253 Command8253 Count 28253 Count 18253 Count 0
Counter & Timer
FFD2HFFD0H
8251-2 Command8251-2 data
RS232C PORT 2
Port address
Port function
FFCAHFFC8H
8259 Command8259 Data
Interrupt control
3FF0H FND Display
3FD8H D/A Converter 8 bit D/A converter
3FD6H
3FD4H3FD2H3FD0H
PPI-1 control word resisterPPI-1 C portPPI-1 B portPPI-1 A port
Experiment for 8 bit output and input
3FCEH3FCCH3FCAH3FC8H
A/D Converter IN3/IN7A/D Converter IN2/IN6A/D Converter IN1/IN5A/D Converter IN0/IN4
8 bit A/D Converter
Example :
*Knowing that, DS=2042H.SI=500H,AX=214E,MOV [SI],AX ;
DS=2042H DS=20420H
SI=500
20920H
20921H
21 4E
AH AL
4E
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Executing a program in MTS-86C
Label Mnemonic Hex code Memory address
Remarks
CODE SEGMENT 0040:
ASSUME CS: CODE & DS: CODE Result will be
MOV AX, 1234H B8, 34, 12 00, 01, 02 stored in AX
MOV CX, 0034H B9, 34, 00 03, 04, 05
ADD CX 03, C1 06, 07
HLT F4 08
CODE ENDS
END
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History of microprocessor
8008 8080 8085 8086
Number of instructions
66 111 113 133
Number of flags 4 5 5 9
Maximum memory size
16K bytes 64K bytes 64K bytes 1 M bytes
I/O ports 8 input24 output
256 input 256 output
256 input 256 output
64K input64K output
Number of pins 18 40 40 40
Address bus width
8 16 16 20
Data bus width 8 8 8 16
Introduction date 1972 1974 1976Q-6,500 at 3 µm
1978Q-29,000 at 3 µm
What Are Microcontrollers?• Microprocessor – Microcontroller what's the diff?• Microprocessors can not stand alone
– instruction decoder, ALU, address/data. busses, timing logic, (CPU)– Has no capability to interact with the outside world
• memory, I/O ports, UARTS, etc. must be added to make it useful • Microcontrollers are small computing systems on a single chip
– Central Processing Unit (CPU)– Program memory – Random Access Memory (RAM) – EEPROM - Electrically Erasable Programmable Read Only Memory– A variety of peripheral devices
• USARTs, Timer/Counters, ADC, DAC, I/O Ports, CANs, SPIs etc.
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Why not a Computer ?
• PC is a general purpose computer. • Can run thousand of software's • Games (NFS , AOE , Call of Duty) • Highly expensive
Why MCU
• Small reflected by the word “MICRO” • Inexpensive • Ideal for doing repetitive tasks • Easy to use • Highly Efficient and fast
• Suppose we want to make a Line following Robot • What do we do ? • Use a computer with 2.4Ghz Intel core I7 with 4 Gb RAM , 500 Gb Hard disk , 1 Gb Graphics Card ??
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ATmega8(L) microcontroller
The Atmel ®AVR® ATmega8 is a low-power CMOS 8-bit microcontroller based on the AVR RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega8 achieves throughputs approaching 1MIPS per MHz, allowing the system designer to optimize power consumption versus processing speed.
Fig7. Pin configuration of ATmega8(L) 28
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CONCLUSION
Finally, you should write a report with clear conception for different contents described above.
References
1) Microprocessor Architecture, Programming and Applications with the 8085/8080Aby Ramesh S. Gaonkar
2) Microprocessors and Interfacing by Douglas V Hall
and3) Internet
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