autumn 2012c.-s. shieh, ec, kuas, taiwan1 the 8051 family microcontroller chin-shiuh shieh csshieh...

Autumn 2012 C.-S. Shieh, EC, KUAS, Taiwan 1

The 8051 Family Microcontroller

Chin-Shiuh Shiehhttp://bit.kuas.edu.tw/~csshieh

Department of Electronic EngineeringNational Kaohsiung University of Applied Sciences, Taiwan


Microcontrollers

• Microprocessors, such as 8086 family, have only CCU and ALU in them. External RAM, ROM, and I/O are required.

• Microcontrollers, such as 8051 family, encompass CCU, ALU, RAM, ROM, and I/O in a single chip, also called single-chip.

• Microcontrollers have limited computational power, but their low-cost make them prevalent in consumer products and small-scale control systems.


Microcontrollers (cont)

• We adopt 8051 family microcontroller in our class for its general structure and manageable system complexity.

• A large number of manufactures offer different variants of 8051 family microcontroller.


ATMEL AT89C51

• AT89C51 / AT89S51 is a popular member of the 8051 family microcontroller from ATMEL.


Features

• 8-bit CPU optimized for control applications

• 128 bytes of on-chip Data RAM, 4K bytes of on-chip Program Memory (Flash Memory/ROM)

• 64K Program Memory address space, 64K Data Memory address space


Features (cont)

• 32 bidirectional and individually addressable I/O lines

• Two 16-bit timer/counters

• Full duplex programmable UART

• 6-source/5-vector interrupt structure with two priority levels


Pin Configurations


Pin Configurations (cont)

• Vcc, GND: supply voltage (5V), ground

• XTAL1, XTAL2: crystal connections for system clock

• RST: reset input

• EA: External Access, EA=5V to enable internal ROM.


Pin Configurations (cont)• Basic hardware configuration



• P0.0~P0.7: Port 0, bidirectional bit-addressable with open drain

• P1.0~P1.7: Port 1, bidirectional bit-addressable with internal pull-ups





• MOV P2,#0Ah ;Copy 0A16 to P2

• MOV P2,#08 ;Copy 08 to P2

• MOV P2,#00110100b;Copy 3416 to P2

• SETB P2.0 ;Set P2.0 to “1”• CLR P2.1 ;Clear P2.1 to “0”• MOV A,P1 ;Copy P1 to A• JB P3.2,LOOP ;Jump to LOOP if P3.1 is “1”



• P0 is open-drain– SETBP0.0;P0.0 = high impedance – CLR P0.1;P0.1 = 0V

• P1, P2, and P3 have internal pull-ups– SETBP1.0;P1.0 = 5V– CLR P1.1;P1.1 = 0V


• "MOV P2,A" will turn on LEDs on P2 whose corresponding bits in A is "0". Notice that I/O port source current is limited.

• If an I/O port is used for input, it's output latch must set to "1". For example, "MOV P1,#0FFh", then "MOV A,P1" will read P1 status into A.

• MOV P1,#0FFh• MOV A,P1


• P0 is open-drain. Pull-up resistor is required. "SETB P0.0" will turn on the relay and "CLR P0.0" will turn it off.

• For button applications, de-bounce circuitry and code is required (5RC=10mS~20mS).


ORG 0000hLOOP:

SETB P2.0LCALL DELAYCLR P2.0LCALL DELAYLJMP LOOP

DELAY:MOV R0,#0FFh

L1: MOV R1,#0FFhL2: DJNZ R1,L2 ; Decrease and jump if not zero

DJNZ R0,L1RETEND


for(R0=255;R0>=0;R0--)

for(R1=255;R1>=0;R1--)

{

}


Pin Configurations



• Alternative Functions of Port 3



• PSEN: Program Store Enable, read strobe for external program memory

• ALE: Address Latch Enable, for multiplexing AD0~AD7

• A8~A15(P2.0~P2.7): high-byte address bus for external addressing

• AD0~AD7(P0.0~P0.7): multiplexed low-byte address bus and data bus for external addressing


Memory Organization

• Separation of program addressing space and data addressing space.


Program Memory


Data Memory


Internal Data Memory

• MOV 12h,#05h• MOV A,3Ch• MOV 0E0h,3Ch

• MOV A,R0

• MOV 20h,#05h• SETB 03h• MOV A,20h; A==0D


Special Function Register Map


• MOV SBUF,#’H’ ;== MOV SBUF,#48h

• MOV SBUF,#’e’


Special Function Register Map (cont)



• MOV P2,#55h == MOV 0A0h,#55h• SETB P1.0• CLR P1.0



• MOV SBUF,A = MOV 99h,0E0h • MOV 99h,A


Special Function Registers

• A, (ACC): Accumulator – MOV A,#02h– ADD A,#03h

• B: B Register – MUL AB

• MOV A,#03h• MOV R0,#02h• MUL AR0

– DIV AB• SP: Stack Pointer • DPTR(DPH,DPL): Data Pointer

– MOV DPTR,#4000h– MOVX A,@DPTR


Special Function Registers (cont)

• P0: Port 0

• P1: Port 1

• P2: Port 2

• P3: Port 3



• TH0: Timer/Counter 0 High Byte

• TL0: Timer/Counter 0 Low Byte

• TH1: Timer/Counter 1 High Byte

• TL1: Timer/Counter 1 Low Byte

• SBUF: Serial Data Buffer – MOV SBUF,A



• PSW: Program Status Word • PCON: Power Control Register • IE: Interrupt Enable Register • IP: Interrupt Priority Register • TCON: Timer/Counter Control Register • TMOD: Timer/Counter Mode Control

Register • SCON: Serial Port Control Register


PSW: Program Status Word


PSW: Program Status Word (cont)

• SETB RS1• CLR RS0


PCON: Power Control Register


• SET SMOD


PCON: Power Control Register (cont)

• SETB SMOD ; Incorrect• MOV A,PCON• ORL A,#10000000b• MOV PCON,A

• CLR GF0 ; Incorrect• MOV A,PCON• ANL A,#11111011b• MOV PCON,A


IE: Interrupt Enable Register

; Enable External Interrupt 0 with high prioritySETB EX0SETB EASETB PX0


IP: Interrupt Priority Register


TCON: Timer/Counter Control Register


TMOD: Timer/Counter Mode Control Register


• 2B• 0B• F8

• 2B• B2• 02• A4


TMOD: Timer/Counter Mode Control Register (cont)

TH1 TL1

FD FD

FF• 8-bit Auto-reload mode


SCON: Serial Port Control Register


• MOV SBUF,A

• MOV A,SBUF


PC: Program Counter

• PC: Program Counter – 16-bit register– Instruction fetching– Auto increase


Interrupt Mechanism


Pin Configurations


Interrupt Mechanism (cont)


Addressing Mode

• Immediate: MOV A,#20h

• Register: MOV A,R0

• Direct: MOV A,30h

• Indirect: MOV A,@R0

• External Data Indirect: MOVX A,@DPTR

• Code Indirect: MOVC A,@A+DPTR


• MOV A,#00h

• ADD A,00h

• ADD A,01h

• ADD A,02h

• …

• ADD A,09h


• int x[10];• int sum;

• sum=0;• sum=sum+x[0];• sum=sum+x[1];• sum=sum+x[2];• …• sum=sum+x[9];


• int x[10];

• int sum;

• for(i=0;i<10;i++)– sum=sum+x[i];


• MOV A,#00h

• MOV R0,#09h

• LOOP:– ADD A,@R0– DJNZR0,LOOP


• int x[10],sum;

• sum=sum+x[0];

• sum=sum+x[1];

• sum=sum+x[2];

• …

• sum=sum+x[9];


• int x[10],sum,i;

• for(i=0i<10;i++)– sum=sum+x[i];


Instruction Set

• ASEM51 v1.3– Assembler Directives

• ORG• EQU

• Emulator 8051 V1.0 or JSIM-51


• JB bit, rel

• JNB bit, rel

• JC rel

• JNC rel

• JZ rel ; Jump if A==0

• JNZ rel


• ADD B,R0

• ANL A,#00001111b

• MOV A,PCON

• ANL A,#01111111b

• MOV PCON,A


• MOV A,00h

• ADD A,04h

• MOV 08h,A

• MOV A,01h

• ADDC A,05h

• MOV 09h,A


• MOV R0,#10

• LOOP:

• …

• …

• …

• DEC R0

• CJNE R0,#00, LOOP

autumn 2012c.-s. shieh, ec, kuas, taiwan1 the 8051 family microcontroller chin-shiuh shieh csshieh...

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