INTRODUCTIONTO 8051MICROCONTROLLER
WHAT IS A MICROCONTROLLER?• All of the components needed for a controller  were built right onto one chip.• Thus A one chi...
Features :• The Intel 8051 is used in embedded  systems  – 8-bit CPU  – 4k bytes ROM for the program  – 128 BYTES of RAM f...
Block DiagramExternal Interrupts   Interrupt           4k          128 bytes           Timer 1    Control           ROM   ...
8051 – PIN DIAGRAM
8051 – 40 PIN IC
• 8051 contains four I/O ports (P0 - P3)                 • Each port can be used as input or output                   (bi-...
IMPORTANT PINS•   PSEN (out): Program Store Enable, the read signal    for external program memory (active low).•   ALE (o...
SIGNALS - OPERATION• Vcc(pin 40):   – Vcc provides supply voltage to the chip.   – The voltage source is +5V.• GND(pin 20)...
RST - RESET• RST(pin 9):reset   – input pin and active high       • The high pulse must be high at least 2 machine        ...
EA & PSEN• EA(pin 31):external access   – There is no on-chip ROM in 8031 and 8032 .   – The EA pin is connected to GND to...
ALE• ALE(pin 30):address latch enable  It is an output pin and is active high.  8051 port 0 provides both address and da...
8051 microcontroller
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8051 microcontroller

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8051 microcontroller

  1. 1. INTRODUCTIONTO 8051MICROCONTROLLER
  2. 2. WHAT IS A MICROCONTROLLER?• All of the components needed for a controller were built right onto one chip.• Thus A one chip computer, or microcontroller was born.• A microcontroller is a highly integrated chip which includes, on one chip, all or most of the parts needed for a controller.• The microcontroller could be called a "one- chip solution".
  3. 3. Features :• The Intel 8051 is used in embedded systems – 8-bit CPU – 4k bytes ROM for the program – 128 BYTES of RAM for variables – 32 I/O lines ( 4 PORTS WITH 8 EACH ) – 2 timers – 1 Serial port – 6 interrupt sources – Low cost (25-30 Rs per chip)
  4. 4. Block DiagramExternal Interrupts Interrupt 4k 128 bytes Timer 1 Control ROM RAM Timer 2 CPU OSC Bus 4 I/O Ports Serial Control P0 P2 P1 P3 TXD RXD Addr/Data
  5. 5. 8051 – PIN DIAGRAM
  6. 6. 8051 – 40 PIN IC
  7. 7. • 8051 contains four I/O ports (P0 - P3) • Each port can be used as input or output (bi-direction) Port 0 Port 1 Port 2 Port 3P0(P0.0~P0.7) P1(P1.0~P1.7) P2(P2.0~P2.7) P3(P3.0~P3.7) 8-bit R/W - 8-bit R/W - General General General Purpose I/O Purpose I/O Purpose I/O Only 8-bit R/W - General Or high if not using Or acts as a Purpose byte of the any of the multiplexed I/O address internal low byte bus for peripherals address and (timers) or data bus for external external memory external memory design interrupts. design
  8. 8. IMPORTANT PINS• PSEN (out): Program Store Enable, the read signal for external program memory (active low).• ALE (out): Address Latch Enable, to latch address outputs at Port0 and Port2• EA (in): External Access Enable, active low to access external program memory locations 0 to 4K• RXD,TXD: UART pins for serial I/O on Port 3• XTAL1 & XTAL2: Crystal inputs for internal oscillator.
  9. 9. SIGNALS - OPERATION• 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): – These 2 pins provide external clock. – Way 1:using a quartz crystal oscillator – Way 2:using a TTL oscillator
  10. 10. RST - RESET• RST(pin 9):reset – input pin and active high • The high pulse must be high at least 2 machine cycles. – power-on reset. • Upon applying a high pulse to RST, the microcontroller will reset and all values in registers will be lost.
  11. 11. EA & PSEN• 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. – active low.• PSEN(pin 29):program store enable – This is an output pin and is connected to the OE pin of the ROM.
  12. 12. ALE• 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.

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