Lecture SOHIL LUHAR
- 2. CONTACT: PROF.SHAHID SIR 8000181198 MR.SOHIL LUHAR 9974638068 MR.RAJVEER SIR 8401130726
- 3. Contents: Introduction Block Diagram and Pin Description of the 8051 Registers Some Simple Instructions Structure of Assembly language and Running an 8051 program Memory mapping in 8051 8051 Flag bits and the PSW register Addressing Modes 16-bit, BCD and Signed Arithmetic in 8051 Stack in the 8051 LOOP and JUMP Instructions CALL Instructions I/O Port Programming
- 4. 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
- 5. The 8051 microcontroller a Harvard architecture (separate instruction/data memories) single chip microcontroller (µC) developed by Intel in 1980 for use in embedded systems. today largely superseded by a vast range of faster and/or functionally enhanced 8051-compatible devices manufactured by more than 20 independent manufacturers
- 6. Block 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
- 7. FeatureFeature 8051 8052 80318051 8052 8031 ROM (program space in bytes)ROM (program space in bytes) 4K4K 8K 0K8K 0K RAM (bytes)RAM (bytes) 128128 256 128256 128 TimersTimers 2 3 22 3 2 I/O pinsI/O pins 32 32 3232 32 32 Serial portSerial port 1 1 11 1 1 Interrupt sourcesInterrupt sources 6 8 66 8 6 Comparison of the 8051 Family Members
- 9. Pin 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)
- 10. Pins of 8051（1/4） 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 Example 4-1 shows the relationship between XTAL and the machine cycle.
- 11. Pins of 8051（2/4） 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 Way 1：Power-on reset circuit Way 2：Power-on reset with debounce
- 12. Pins of 8051（3/4） /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. See Chapter 14.
- 13. Pins of 8051（4/4） 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.
- 14. Figure 4-2 (a). XTAL Connection to 8051 Using a quartz crystal oscillator We can observe the frequency on the XTAL2 pin. XTAL2 XTAL1 G N D
- 15. Figure 4-2 (b). XTAL Connection to an External Clock Source Using a TTL oscillator XTAL2 is unconnected. N C EXTERNAL OSCILLATOR SIGNAL XTAL2 XTAL1 GND
- 16. RESET Value of Some 8051 Registers: 00000000DPTRDPTR 00070007SPSP 00000000PSWPSW 00000000BB 00000000ACCACC 00000000PCPC Reset ValueReset ValueRegisterRegister RAM are all zero.RAM are all zero.
- 17. Figure 4-3 (a). 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
- 18. Figure 4-3 (b). Power-On RESET with Debounce EA/VPP X1 X2 RST Vcc 10 uF 8.2 K 30 pF 9 31
- 19. Pins 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).
- 20. 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
- 21. Memory Map (RAM)
- 22. CPU timing Most 8051 instructions are executed in one cycle. MUL (multiply) and DIV (divide) are the only instructions that take more than two cycles to complete (four cycles) Normally two code bytes are fetched from the program memory during every machine cycle. The only exception to this is when a MOVX instruction is executed. MOVX is a one-byte, 2-cycle instruction that accesses external data memory. During a MOVX, the two fetches in the second cycle are skipped while the external data memory is being addressed and strobed.
- 24. Example : Find the machine cycle forFind the machine cycle for (a) XTAL = 11.0592 MHz(a) XTAL = 11.0592 MHz (b) XTAL = 16 MHz.(b) XTAL = 16 MHz. Solution:Solution: (a) 11.0592 MHz / 12 = 921.6 kHz;(a) 11.0592 MHz / 12 = 921.6 kHz; machine cycle = 1 / 921.6 kHz = 1.085machine cycle = 1 / 921.6 kHz = 1.085 ss (b) 16 MHz / 12 = 1.333 MHz;(b) 16 MHz / 12 = 1.333 MHz; machine cycle = 1 / 1.333 MHz = 0.75machine cycle = 1 / 1.333 MHz = 0.75 ss
- 27. Timers 4 marks 8051 has two 16-bit on-chip timers that can be used for timing durations or for counting external events The high byte for timer 1 (TH1) is at address 8DH while the low byte (TL1) is at 8BH The high byte for timer 0 (TH0) is at 8CH while the low byte (TL0) is at 8AH. Timer Mode Register (TMOD) is at address 88H
- 28. Timer Mode Register Bit 7: Gate bit; when set, timer only runs while INT high. (T0) Bit 6: Counter/timer select bit; when set timer is an event counter when cleared timer is an interval timer (T0) Bit 5: Mode bit 1 (T0) Bit 4: Mode bit 0 (T0) Bit 3: Gate bit; when set, timer only runs while INT high. (T1) Bit 2: Counter/timer select bit; when set timer is an event counter when cleared timer is an interval timer (T1) Bit 1: Mode bit 1 (T1) Bit 0: Mode bit 0 (T1)
- 29. Timer Modes M1-M0: 00 (Mode 0) – 13-bit mode (not commonly used) M1-M0: 01 (Mode 1) - 16-bit timer mode M1-M0: 10 (Mode 2) - 8-bit auto-reload mode M1-M0: 11 (Mode 3) – Split timer mode
- 30. 8051 Interrupt Vector Table
- 31. The Stack and Stack Pointer The Stack Pointer, like all registers except DPTR and PC, may hold an 8-bit (1- byte) value. The Stack Pointer is used to indicate where the next value to be removed from the stack should be taken from. When you push a value onto the stack, the 8051 first increments the value of SP and then stores the value at the resulting memory location. When you pop a value off the stack, the 8051 returns the value from the memory location indicated by SP, and then decrements the value of SP. This order of operation is important. When the 8051 is initialized SP will be initialized to 07h. If you immediately push a value onto the stack, the value will be stored in Internal RAM address 08h. This makes sense taking into account what was mentioned two paragraphs above: First the 8051 will increment the value of SP (from 07h to 08h) and then will store the pushed value at that memory address (08h). SP is modified directly by the 8051 by six instructions: PUSH, POP, ACALL, LCALL, RET, and RETI. It is also used intrinsically whenever an interrupt is triggered
- 32. Any Query?