Sunday, July 28, 2013 Mahdi Hassanpour
Microcontroller FamiliesMicrocontroller Families
 68H12: Motorola 68H11, 68HC12, …...
Sunday, July 28, 2013 Mahdi Hassanpour
8051 History8051 History
 Introduced 1980Introduced 1980
 12 MHz12 MHz
 128128 b...
Sunday, July 28, 2013 Mahdi Hassanpour
8051 Manufacturers8051 Manufacturers
 AMD: Enhanced 8051AMD: Enhanced 8051 partspa...
Why do we need to learnWhy do we need to learn
Microprocessors/controllers?Microprocessors/controllers?
 The microprocess...
Different aspects of a
microprocessor/controller
 Hardware :Interface to the real world
 Software :order how to deal wit...
The necessary tools for aThe necessary tools for a
microprocessor/controllermicroprocessor/controller
 CPU: Central Proce...
CPU
General-
Purpose
Micro-
processor
RAM ROM I/O
Port
Timer
Serial
COM
Port
Data Bus
Address Bus
General-Purpose Micropro...
RAM ROM
I/O
Port
Timer
Serial
COM
Port
Microcontroller
CPU
 A smaller computer
 On-chip RAM, ROM, I/O ports...
 Example...
Microprocessor
 CPU is stand-alone, RAM,
ROM, I/O, timer are separate
 designer can decide on the
amount of ROM, RAM and...
 Embedded system means the processor is embedded into that
application.
 An embedded product uses a microprocessor or mi...
1. meeting the computing needs of the task efficiently and cost
effectively
• speed, the amount of ROM and RAM, the number...
Block DiagramBlock Diagram
CPU
On-chip
RAM
On-chip
ROM for
program
code
4 I/O Ports
Timer 0
Serial
PortOSC
Interrupt
Contr...
Sunday, July 28, 2013 Mahdi Hassanpour
PackagingPackaging
 Plastic Dual In-Line package (PDIL)Plastic Dual In-Line packag...
Sunday, July 28, 2013 Mahdi Hassanpour
Packaging IPackaging I
 Very small Quad Flat Package (VQFP)Very small Quad Flat Pa...
Sunday, July 28, 2013 Mahdi Hassanpour
Packaging IIPackaging II
 Plastic Leaded Chip Carrier (PLCC)Plastic Leaded Chip Ca...
Pin Description of the 8051Pin Description of the 8051
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
40
39
38
37
36
3...
Pins of 8051Pins of 8051
 Vcc ( pin 40 ):
– Vcc provides supply voltage to the chip.
– The voltage source is +5V.
 GND (...
Figure (a). XTAL Connection to 8051Figure (a). XTAL Connection to 8051
C2
30pF
C1
30pF
XTAL2
XTAL1
GND
 Using a quartz cr...
Pins of 8051Pins of 8051 (( 2/42/4 ))
 RST ( pin 9 ): reset
– It is an input pin and is active high ( normally low ) .
 ...
Figure (b). Power-On RESET CircuitFigure (b). Power-On RESET Circuit
30 pF
30 pF
8.2 K
10 uF
+
Vcc
11.0592 MHz
EA/VPP
X1
X...
Pins of 8051Pins of 8051 (( 3/43/4 ))
 /EA ( pin 31 ): external access
– There is no on-chip ROM in 8031 and 8032 .
– The...
Pins of 8051Pins of 8051 (( 4/44/4 ))
 ALE ( pin 30 ): address latch enable
– It is an output pin and is active high.
– 8...
Pins of I/O PortPins of I/O Port
 The 8051 has four I/O ports
– Port 0 ( pins 32-39 ): P0 ( P0.0 ~ P0.7 )
– Port 1 ( pins...
Hardware Structure of I/O PinHardware Structure of I/O Pin
 Each pin of I/O ports
– Internal CPU bus : communicate with C...
D LatchD Latch::
A Pin of Port 1A Pin of Port 1
8051 IC
D Q
Clk Q
Vcc
Load(L1)
Read latch
Read pin
Write to latch
Internal CPU
bus
M1
P1.X
...
Writing “1” to Output Pin P1.XWriting “1” to Output Pin P1.X
D Q
Clk Q
Vcc
Load(L1)
Read latch
Read pin
Write to latch
Int...
Writing “0” to Output Pin P1.XWriting “0” to Output Pin P1.X
D Q
Clk Q
Vcc
Load(L1)
Read latch
Read pin
Write to latch
Int...
Reading “High” at Input PinReading “High” at Input Pin
D Q
Clk Q
Vcc
Load(L1)
Read latch
Read pin
Write to latch
Internal ...
Reading “Low” at Input PinReading “Low” at Input Pin
D Q
Clk Q
Vcc
Load(L1)
Read latch
Read pin
Write to latch
Internal CP...
Other PinsOther Pins
 P1, P2, and P3 have internal pull-up resisters.
– P1, P2, and P3 are not open drain.
 P0 has no in...
A Pin of Port 0A Pin of Port 0
8051 IC
D Q
Clk Q
Read latch
Read pin
Write to latch
Internal CPU
bus
M1
P0.X
pinP1.X
TB1
T...
Port 0 with Pull-Up ResistorsPort 0 with Pull-Up Resistors
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
DS5000
8751
8951
Vcc
10...
Port 3 Alternate FunctionsPort 3 Alternate Functions
1717RDRDP3.7P3.7
1616WRWRP3.6P3.6
1515T1T1P3.5P3.5
1414T0T0P3.4P3.4
1...
RESET Value of Some 8051 Registers:RESET Value of Some 8051 Registers:
0000DPTR
0007SP
0000PSW
0000B
0000ACC
0000PC
Reset ...
Registers
A
B
R0
R1
R3
R4
R2
R5
R7
R6
DPH DPL
PC
DPTR
PC
Some 8051 16-bit Register
Some 8-bitt Registers of
the 8051
Memory mapping in 8051Memory mapping in 8051
 ROM memory map in 8051 family
0000H
0FFFH
0000H
1FFFH
0000H
7FFFH
8751
AT89...
Sunday, July 28, 2013 Mahdi Hassanpour
8051 Internal RAM8051 Internal RAM
Sunday, July 28, 2013 Mahdi Hassanpour
Special Function Registers (SFRs)Special Function Registers (SFRs)
 RAM memory space allocation in the 8051
7FH
30H
2FH
20H
1FH
17H
10H
0FH
07H
08H
18H
00H
Register Bank 0
)Stack) Register...
Stack in the 8051Stack in the 8051
 The register used to access
the stack is called SP (stack
pointer) register.
 The st...
Timer :Timer :
TMOD RegisterTMOD Register::
 Gate : When set, timer only runs while INT(0,1) is
high.
 C/T : Counter/Timer select bit.
...
TCON Register:TCON Register:
 TF1: Timer 1 overflow flag.
 TR1: Timer 1 run control bit.
 TF0: Timer 0 overflag.
 TR0:...
Interrupt :Interrupt :
Interrupt Enable Register :Interrupt Enable Register :
 EA : Global enable/disable.
 --- : Undefined.
 ET2 :Enable Time...
Sunday, July 28, 2013 Mahdi Hassanpour
PortsPorts
 Driving low-power peripherals i.e.. LEDs, relaysDriving low-power peri...
Sunday, July 28, 2013 Mahdi Hassanpour
Accessing Ports in CAccessing Ports in C
void main (void)void main (void)
{{
unsign...
Sunday, July 28, 2013 Mahdi Hassanpour
A simple project using AT89C51A simple project using AT89C51
 Here we’ve designed,...
Sunday, July 28, 2013 Mahdi Hassanpour
A simple project using AT89C51A simple project using AT89C51
Microcontroller 8051 gs
Microcontroller 8051 gs
Microcontroller 8051 gs
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  • Intel’s x86: 8086,8088,80386,80486, Pentium Motorola’s 680x0: 68000, 68010, 68020,68030,6040
  • versatility 多用途的 : any number of applications for PC
  • processor 整合到整個系統中 , 你只看到此系統的外觀 , 應用 , 感覺不到有 processor 在其中 . Embedded system 通常只有一項應用 , 而 PC 有許多 applications (game, accounting, fax, mail...) A printer is an example of embedded system since the processor inside it performs one task only.
  • Program is to read data from P0 and then send data to P1
  • Microcontroller 8051 gs

    1. 1. Sunday, July 28, 2013 Mahdi Hassanpour Microcontroller FamiliesMicrocontroller Families  68H12: Motorola 68H11, 68HC12, …68H12: Motorola 68H11, 68HC12, …  8051: Intel 8051, 8052, 80251,…8051: Intel 8051, 8052, 80251,…  PIC: Microchip PIC16F628, 18F452, 16F877, …PIC: Microchip PIC16F628, 18F452, 16F877, …  AVR: Atmel ATmega128, ATtiny28L, AT90S8515,…AVR: Atmel ATmega128, ATtiny28L, AT90S8515,…  We are going to look at 8051s
    2. 2. Sunday, July 28, 2013 Mahdi Hassanpour 8051 History8051 History  Introduced 1980Introduced 1980  12 MHz12 MHz  128128 bytesbytes Internal RAMInternal RAM  4 Kbytes ROM4 Kbytes ROM  1 Serial port support1 Serial port support
    3. 3. Sunday, July 28, 2013 Mahdi Hassanpour 8051 Manufacturers8051 Manufacturers  AMD: Enhanced 8051AMD: Enhanced 8051 partsparts (no longer producing 80x51 parts)(no longer producing 80x51 parts)  Atmel: FLASH and semi-custom partsAtmel: FLASH and semi-custom parts  Dallas: Battery backed, program download, and fastestDallas: Battery backed, program download, and fastest variantsvariants  Intel: 8051 through 80c51gb / 80c51slIntel: 8051 through 80c51gb / 80c51sl  ISSI: IS80C51/31 runs up to 40MHzISSI: IS80C51/31 runs up to 40MHz  Matra: 80c154, low voltage static variantsMatra: 80c154, low voltage static variants  OKI: 80c154, mask partsOKI: 80c154, mask parts  Philips87c748 thru 89c588 - more variants than anyone elsePhilips87c748 thru 89c588 - more variants than anyone else – now NXPnow NXP  Siemens: 80c501 through 80c517a, and SIECO coresSiemens: 80c501 through 80c517a, and SIECO cores  SMC: COM20051 with ARCNET token bus network engineSMC: COM20051 with ARCNET token bus network engine  SSI: 80x52, 2 x HDLC variant for MODEM useSSI: 80x52, 2 x HDLC variant for MODEM use
    4. 4. Why do we need to learnWhy do we need to learn Microprocessors/controllers?Microprocessors/controllers?  The microprocessor is the core of computer systems.  Nowadays many communication, digital entertainment, portable devices, are controlled by them.  A designer should know what types of components he needs, ways to reduce production costs and product reliable..
    5. 5. Different aspects of a microprocessor/controller  Hardware :Interface to the real world  Software :order how to deal with inputs
    6. 6. The necessary tools for aThe necessary tools for a microprocessor/controllermicroprocessor/controller  CPU: Central Processing Unit  I/O: Input /Output  Bus: Address bus & Data bus  Memory: RAM & ROM  Timer  Interrupt  Serial Port  Parallel Port
    7. 7. CPU General- Purpose Micro- processor RAM ROM I/O Port Timer Serial COM Port Data Bus Address Bus General-Purpose Microprocessor System Microprocessors:Microprocessors:  CPU for Computers  No RAM, ROM, I/O on CPU chip itself  Example : Intel’s x86, Motorola’s 680x0 Many chips on mother’s board General-purpose microprocessor
    8. 8. RAM ROM I/O Port Timer Serial COM Port Microcontroller CPU  A smaller computer  On-chip RAM, ROM, I/O ports...  Example : Motorola’s 6811, Intel’s 8051, Zilog’s Z8 and PIC 16X A single chip Microcontroller :
    9. 9. Microprocessor  CPU is stand-alone, RAM, ROM, I/O, timer are separate  designer can decide on the amount of ROM, RAM and I/O ports.  expansive  versatility  general-purpose Microcontroller • CPU, RAM, ROM, I/O and timer are all on a single chip • fix amount of on-chip ROM, RAM, I/O ports • for applications in which cost, power and space are critical • single-purpose Microprocessor vs. Microcontroller
    10. 10.  Embedded system means the processor is embedded into that application.  An embedded product uses a microprocessor or microcontroller to do one task only.  In an embedded system, there is only one application software that is typically burned into ROM.  Example : printer, keyboard, video game player Embedded System
    11. 11. 1. meeting the computing needs of the task efficiently and cost effectively • speed, the amount of ROM and RAM, the number of I/O ports and timers, size, packaging, power consumption • easy to upgrade • cost per unit 2. availability of software development tools • assemblers, debuggers, C compilers, emulator, simulator, technical support 3. wide availability and reliable sources of the microcontrollers. Three criteria in Choosing a Microcontroller
    12. 12. Block DiagramBlock Diagram CPU On-chip RAM On-chip ROM for program code 4 I/O Ports Timer 0 Serial PortOSC Interrupt Control External interrupts Timer 1 Timer/Counter Bus Control TxD RxDP0 P1 P2 P3 Address/Data Counter Inputs
    13. 13. Sunday, July 28, 2013 Mahdi Hassanpour PackagingPackaging  Plastic Dual In-Line package (PDIL)Plastic Dual In-Line package (PDIL)
    14. 14. Sunday, July 28, 2013 Mahdi Hassanpour Packaging IPackaging I  Very small Quad Flat Package (VQFP)Very small Quad Flat Package (VQFP)
    15. 15. Sunday, July 28, 2013 Mahdi Hassanpour Packaging IIPackaging II  Plastic Leaded Chip Carrier (PLCC)Plastic Leaded Chip Carrier (PLCC)
    16. 16. Pin Description of the 8051Pin Description of the 8051 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 RST (RXD)P3.0 (TXD)P3.1 (T0)P3.4 (T1)P3.5 XTAL2 XTAL1 GND (INT0)P3.2 (INT1)P3.3 (RD)P3.7 (WR)P3.6 Vcc P0.0(AD0 )P0.1(AD1) P0.2(AD2 )P0.3(AD3) P0.4(AD4) P0.5(AD5) P0.6(AD6) P0.7(AD7) EA/VPP ALE/PROG PSEN P2.7(A15) P2.6(A14 )P2.5(A13 )P2.4(A12 )P2.3(A11 )P2.2(A10) P2.1(A9) P2.0(A8) 8051 (8031) 
    17. 17. Pins of 8051Pins of 8051  Vcc ( pin 40 ): – Vcc provides supply voltage to the chip. – The voltage source is +5V.  GND ( pin 20 ): ground  XTAL1 and XTAL2 ( pins 19,18 )
    18. 18. Figure (a). XTAL Connection to 8051Figure (a). XTAL Connection to 8051 C2 30pF C1 30pF XTAL2 XTAL1 GND  Using a quartz crystal oscillator  We can observe the frequency on the XTAL2 pin. 
    19. 19. Pins of 8051Pins of 8051 (( 2/42/4 ))  RST ( pin 9 ): reset – It is an input pin and is active high ( normally low ) .  The high pulse must be high at least 2 machine cycles. – It is a power-on reset.  Upon applying a high pulse to RST, the microcontroller will reset and all values in registers will be lost.  Reset values of some 8051 registers 
    20. 20. Figure (b). Power-On RESET CircuitFigure (b). Power-On RESET Circuit 30 pF 30 pF 8.2 K 10 uF + Vcc 11.0592 MHz EA/VPP X1 X2 RST 31 19 18 9 
    21. 21. Pins of 8051Pins of 8051 (( 3/43/4 ))  /EA ( pin 31 ): external access – There is no on-chip ROM in 8031 and 8032 . – The /EA pin is connected to GND to indicate the code is stored externally. – /PSEN & ALE are used for external ROM. – For 8051, /EA pin is connected to Vcc. – “/” means active low.  /PSEN ( pin 29 ): program store enable – This is an output pin and is connected to the OE pin of the ROM.
    22. 22. Pins of 8051Pins of 8051 (( 4/44/4 ))  ALE ( pin 30 ): address latch enable – It is an output pin and is active high. – 8051 port 0 provides both address and data. – The ALE pin is used for de-multiplexing the address and data by connecting to the G pin of the 74LS373 latch.  I/O port pins – The four ports P0, P1, P2, and P3. – Each port uses 8 pins. – All I/O pins are bi-directional..
    23. 23. Pins of I/O PortPins of I/O Port  The 8051 has four I/O ports – Port 0 ( pins 32-39 ): P0 ( P0.0 ~ P0.7 ) – Port 1 ( pins 1-8 ) : P1 ( P1.0 ~ P1.7 ) – Port 2 ( pins 21-28 ): P2 ( P2.0 ~ P2.7 ) – Port 3 ( pins 10-17 ): P3 ( P3.0 ~ P3.7 ) – Each port has 8 pins.  Named P0.X ( X=0,1,...,7 ) , P1.X, P2.X, P3.X  Ex : P0.0 is the bit 0 ( LSB ) of P0  Ex : P0.7 is the bit 7 ( MSB ) of P0  These 8 bits form a byte.  Each port can be used as input or output (bi-direction). 
    24. 24. Hardware Structure of I/O PinHardware Structure of I/O Pin  Each pin of I/O ports – Internal CPU bus : communicate with CPU – A D latch store the value of this pin  D latch is controlled by “Write to latch” – Write to latch = 1 : write data into the D latch – 2 Tri-state buffer :  TB1: controlled by “Read pin” – Read pin = 1 : really read the data present at the pin  TB2: controlled by “Read latch” – Read latch = 1 : read value from internal latch – A transistor M1 gate  Gate=0: open  Gate=1: close
    25. 25. D LatchD Latch::
    26. 26. A Pin of Port 1A Pin of Port 1 8051 IC D Q Clk Q Vcc Load(L1) Read latch Read pin Write to latch Internal CPU bus M1 P1.X pinP1.X TB1 TB2 P0.x
    27. 27. Writing “1” to Output Pin P1.XWriting “1” to Output Pin P1.X D Q Clk Q Vcc Load(L1) Read latch Read pin Write to latch Internal CPU bus M1 P1.X pinP1.X 8051 IC 2. output pin is Vcc1. write a 1 to the pin 1 0 output 1 TB1 TB2
    28. 28. Writing “0” to Output Pin P1.XWriting “0” to Output Pin P1.X D Q Clk Q Vcc Load(L1) Read latch Read pin Write to latch Internal CPU bus M1 P1.X pinP1.X 8051 IC 2. output pin is ground1. write a 0 to the pin 0 1 output 0 TB1 TB2
    29. 29. Reading “High” at Input PinReading “High” at Input Pin D Q Clk Q Vcc Load(L1) Read latch Read pin Write to latch Internal CPU bus M1 P1.X pin P1.X 8051 IC 2. MOV A,P1 external pin=High 1. write a 1 to the pin MOV P1,#0FFH 1 0 3. Read pin=1 Read latch=0 Write to latch=1 1 TB1 TB2
    30. 30. Reading “Low” at Input PinReading “Low” at Input Pin D Q Clk Q Vcc Load(L1) Read latch Read pin Write to latch Internal CPU bus M1 P1.X pin P1.X 8051 IC 2. MOV A,P1 external pin=Low1. write a 1 to the pin MOV P1,#0FFH 1 0 3. Read pin=1 Read latch=0 Write to latch=1 0 TB1 TB2
    31. 31. Other PinsOther Pins  P1, P2, and P3 have internal pull-up resisters. – P1, P2, and P3 are not open drain.  P0 has no internal pull-up resistors and does not connects to Vcc inside the 8051. – P0 is open drain. – Compare the figures of P1.X and P0.X.   However, for a programmer, it is the same to program P0, P1, P2 and P3.  All the ports upon RESET are configured as output.
    32. 32. A Pin of Port 0A Pin of Port 0 8051 IC D Q Clk Q Read latch Read pin Write to latch Internal CPU bus M1 P0.X pinP1.X TB1 TB2 P1.x
    33. 33. Port 0 with Pull-Up ResistorsPort 0 with Pull-Up Resistors P0.0 P0.1 P0.2 P0.3 P0.4 P0.5 P0.6 P0.7 DS5000 8751 8951 Vcc 10 K Port0
    34. 34. Port 3 Alternate FunctionsPort 3 Alternate Functions 1717RDRDP3.7P3.7 1616WRWRP3.6P3.6 1515T1T1P3.5P3.5 1414T0T0P3.4P3.4 1313INT1INT1P3.3P3.3 1212INT0INT0P3.2P3.2 1111TxDTxDP3.1P3.1 1010RxDRxDP3.0P3.0 PinPinFunctionFunctionP3 BitP3 Bit 
    35. 35. RESET Value of Some 8051 Registers:RESET Value of Some 8051 Registers: 0000DPTR 0007SP 0000PSW 0000B 0000ACC 0000PC Reset ValueRegister RAM are all zero.. 
    36. 36. Registers A B R0 R1 R3 R4 R2 R5 R7 R6 DPH DPL PC DPTR PC Some 8051 16-bit Register Some 8-bitt Registers of the 8051
    37. 37. Memory mapping in 8051Memory mapping in 8051  ROM memory map in 8051 family 0000H 0FFFH 0000H 1FFFH 0000H 7FFFH 8751 AT89C51 8752 AT89C52 4k DS5000-32 8k 32k from Atmel Corporation from Dallas Semiconductor
    38. 38. Sunday, July 28, 2013 Mahdi Hassanpour 8051 Internal RAM8051 Internal RAM
    39. 39. Sunday, July 28, 2013 Mahdi Hassanpour Special Function Registers (SFRs)Special Function Registers (SFRs)
    40. 40.  RAM memory space allocation in the 8051 7FH 30H 2FH 20H 1FH 17H 10H 0FH 07H 08H 18H 00H Register Bank 0 )Stack) Register Bank 1 Register Bank 2 Register Bank 3 Bit-Addressable RAM Scratch pad RAM
    41. 41. Stack in the 8051Stack in the 8051  The register used to access the stack is called SP (stack pointer) register.  The stack pointer in the 8051 is only 8 bits wide, which means that it can take value 00 to FFH. When 8051 powered up, the SP register contains value 07. 7FH 30H 2FH 20H 1FH 17H 10H 0FH 07H 08H 18H 00H Register Bank 0 )Stack) Register Bank 1 Register Bank 2 Register Bank 3 Bit-Addressable RAM Scratch pad RAM
    42. 42. Timer :Timer :
    43. 43. TMOD RegisterTMOD Register::  Gate : When set, timer only runs while INT(0,1) is high.  C/T : Counter/Timer select bit.  M1 : Mode bit 1.  M0 : Mode bit 0.
    44. 44. TCON Register:TCON Register:  TF1: Timer 1 overflow flag.  TR1: Timer 1 run control bit.  TF0: Timer 0 overflag.  TR0: Timer 0 run control bit.  IE1: External interrupt 1 edge flag.  IT1: External interrupt 1 type flag.  IE0: External interrupt 0 edge flag.  IT0: External interrupt 0 type flag.
    45. 45. Interrupt :Interrupt :
    46. 46. Interrupt Enable Register :Interrupt Enable Register :  EA : Global enable/disable.  --- : Undefined.  ET2 :Enable Timer 2 interrupt.  ES :Enable Serial port interrupt.  ET1 :Enable Timer 1 interrupt.  EX1 :Enable External 1 interrupt.  ET0 : Enable Timer 0 interrupt.  EX0 : Enable External 0 interrupt..
    47. 47. Sunday, July 28, 2013 Mahdi Hassanpour PortsPorts  Driving low-power peripherals i.e.. LEDs, relaysDriving low-power peripherals i.e.. LEDs, relays
    48. 48. Sunday, July 28, 2013 Mahdi Hassanpour Accessing Ports in CAccessing Ports in C void main (void)void main (void) {{ unsigned int i;unsigned int i; /* Delay var *//* Delay var */ unsigned char j;unsigned char j; /* LED var *//* LED var */ while (1)while (1) /* Loop forever *//* Loop forever */ {{ for (j=0x01; j< 0x80; j<<=1) /* Blink LED 0, 1, 2, 3, 4, 5, 6 */for (j=0x01; j< 0x80; j<<=1) /* Blink LED 0, 1, 2, 3, 4, 5, 6 */ {{ P1 = j;P1 = j; /* Output to LED Port *//* Output to LED Port */ msdelay(2000);msdelay(2000); }} for (j=0x80; j> 0x01; j>>=1) /* Blink LED 6, 5, 4, 3, 2, 1 */for (j=0x80; j> 0x01; j>>=1) /* Blink LED 6, 5, 4, 3, 2, 1 */ {{ P1 = j;P1 = j; /* Output to LED Port *//* Output to LED Port */ msdelay(2000);msdelay(2000); }} }} }}
    49. 49. Sunday, July 28, 2013 Mahdi Hassanpour A simple project using AT89C51A simple project using AT89C51  Here we’ve designed, built and programmed a digitalHere we’ve designed, built and programmed a digital BCD counter that counts from 0 to 9 on a 7SegmentBCD counter that counts from 0 to 9 on a 7Segment display.display.  We use register A as Accumulator, in each delayed cycleWe use register A as Accumulator, in each delayed cycle the accumulator increments by one and result is showedthe accumulator increments by one and result is showed on the 7segment display.on the 7segment display.
    50. 50. Sunday, July 28, 2013 Mahdi Hassanpour A simple project using AT89C51A simple project using AT89C51

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