Microcontroller 8051

Chia sẻ: anhkong

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. CPU is stand-alone, RAM, ROM, I/O, timer are separate.

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Nội dung Text: Microcontroller 8051

 

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  2. Why do we need to learn 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. 2
  3. Different aspects of a microprocessor/controller • Hardware :Interface to the real world • Software :order how to deal with inputs 3
  4. The necessary tools for a microprocessor/controller • CPU: Central Processing Unit • I/O: Input /Output • Bus: Address bus & Data bus • Memory: RAM & ROM • Timer • Interrupt • Serial Port • Parallel Port 4
  5. Microprocessors: General-purpose microprocessor • 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 Data Bus CPU General- Serial Purpose RAM ROM I/O Timer COM Micro- Port Port processor Address Bus General-Purpose Microprocessor System 5
  6. Microcontroller : • A smaller computer • On-chip RAM, ROM, I/O ports... • Example Motorola’s 6811, Intel’s 8051, Zilog’s Z8 and PIC 16X CPU RAM ROM A single chip Serial I/O Timer COM Port Port Microcontroller 6
  7. Microprocessor vs. Microcontroller Microprocessor Microcontroller • CPU is stand-alone, RAM, • CPU, RAM, ROM, I/O and ROM, I/O, timer are separate timer are all on a single chip • designer can decide on the amount of ROM, RAM and I/O • fix amount of on-chip ROM, ports. RAM, I/O ports • expansive • for applications in which cost, • versatility power and space are critical • general-purpose • single-purpose 7
  8. Embedded System • 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 E printer, keyboard, video game player 8
  9. Three criteria in Choosing a Microcontroller 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. 9
  10. Block Diagram External interrupts On-chip Timer/Counter Interrupt ROM for On-chip Timer 1 Counter Control program code RAM Timer 0 Inputs CPU Bus Serial 4 I/O Ports OSC Control Port P0 P1 P2 P3 TxD RxD Address/Data 10
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  12. Pin Description of the 8051 P1.0 1 40 Vcc P1.1 2 39 P0.0(AD0 P1.2 3 38 P0.1(AD1) ) P1.3 4 8051 37 P0.2(AD2 P0.3(AD3) P1.4 5 36 ) P1.5 6 (8031) 35 P0.4(AD4) P1.6 7 34 P0.5(AD5) P1.7 8 33 P0.6(AD6) RST 9 32 P0.7(AD7) (RXD)P3.0 10 31 EA/VPP (TXD)P3.1 11 30 ALE/PROG (INT0)P3.2 12 29 PSEN (INT1)P3.3 13 28 P2.7(A15) (T0)P3.4 14 27 P2.6(A14) (T1)P3.5 15 26 P2.5(A13) (WR)P3.6 16 25 P2.4(A12) (RD)P3.7 17 24 P2.3(A11) XTAL2 18 23 P2.2(A10) XTAL1 19 22 P2.1(A9) GND 20 21 P2.0(A8)  12
  13. Packing Types of 8051 • The 8051 family members come in different packages, such as DIP dual in-line package p ,QFP , quad flat package q and LLC L leadless chip carrier l . – See Appendix H Pages 427-429 P • They all have 40 pins. • Figure 4-1. 8051 Pin Diagram 13
  14. 8051 Pin Diagram PDIP/Cerdip P1.0 1 40 Vcc P1.1 2 39 P0.0(AD0 P1.2 3 38 ) 0.1(AD1) P P1.3 4 8051 37 P0.2(AD2 ) 0.3(AD3) P1.4 5 36 P P1.5 6 (8031) 35 P0.4(AD4) P1.6 7 34 P0.5(AD5) P1.7 8 33 P0.6(AD6) RST 9 32 P0.7(AD7) (RXD)P3.0 10 31 EA/VPP (TXD)P3.1 11 30 ALE/PROG (INT0)P3.2 12 29 PSEN (INT1)P3.3 13 28 P2.7(A15) (T0)P3.4 14 27 P2.6(A14) (T1)P3.5 15 26 P2.5(A13) (WR)P3.6 16 25 P2.4(A12) (RD)P3.7 17 24 P2.3(A11) XTAL2 18 23 P2.2(A10) XTAL1 19 22 P2.1(A9) GND 20 21 P2.0(A8) 14
  15. Pins of 8051 1/4 1 • Vcc V pin 40 p i – Vcc provides supply voltage to the chip. – The voltage source is +5V. • GND G pin 20 p i ground • XTAL1 and XTAL2 X pins 19,18 p i – These 2 pins provide external clock. – Way 1 W using a quartz crystal oscillator  – Way 2 W using a TTL oscillator  – Example 4-1 shows the relationship between XTAL and the machine cycle.  15
  16. Pins of 8051 P 2/4 2 • RST R pin 9 p i reset – It is an input pin and is active high I normally low n . • 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  – Way 1 W Power-on reset circuit  – Way 2 W Power-on reset with debounce  16
  17. Pins of 8051 P 3/4 3 • /EA / pin 31 p i 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 p i program store enable – This is an output pin and is connected to the OE pin of the ROM. – See Chapter 14. 17
  18. Pins of 8051 P 4/4 4 • ALE A pin 30 p i 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. 18
  19. Figure 4-2 (a). XTAL Connection to 8051 • Using a quartz crystal oscillator • We can observe the frequency on the XTAL2 pin. C2 XTAL2 30pF C1 XTAL1 30pF GND  19
  20. Figure 4-2 (b). XTAL Connection to an External Clock Source • Using a TTL oscillator • XTAL2 is unconnected. NC XTAL2 EXTERNAL OSCILLATOR XTAL1 SIGNAL GND  20
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