The 8051 Microcontroller and Embedded Systems Using Assembly and C Second Edition Muhammad Ali Mazidi Janice Gillispie Mazidi Rolin D. McKinlay CONTENTS (cid:136) Introduction to Computing (cid:136) The 8051 Microcontrollers (cid:136) 8051 Assembly Language Programming (cid:136) Branch Instructions (cid:136) I/O Port Programming (cid:136) 8051 Addressing Modes (cid:136) Arithmetic & Logic Instructions And Programs (cid:136) 8051 Programming in C (cid:136) 8051 Hardware Connection and Hex File (cid:136) 8051 Timer/Counter Programming in Assembly and C (cid:136) 8051 Serial Port Programming in Assembly and C (cid:136) Interrupts Programming in Assembly and C (cid:136) 8051 Interfacing to External Memory (cid:136) 8051 Real World Interfacing I: LCD,ADC AND SENSORS (cid:136) LCD and Keyboard Interfacing (cid:136) 8051 Interfacing with 8255 INTRODUCTION TO COMPUTING The 8051 Microcontroller and Embedded Systems: Using Assembly and C Mazidi, Mazidi and McKinlay Chung-Ping Young 楊中平 Home Automation, Networking, and Entertainment Lab Dept. of Computer Science and Information Engineering National Cheng Kung University, TAIWAN Numbering and coding systems (cid:137) OUTLINES Digital primer (cid:137) Inside the computer (cid:137) Department of Computer Science and Information Engineering HANEL National Cheng Kung University, TAIWAN 2 Human beings use base 10 (decimal) (cid:137) NUMBERING arithmetic AND CODING There are 10 distinct symbols, 0, 1, 2, …, SYSTEMS (cid:190) 9 Decimal and Computers use base 2 (binary) system (cid:137) Binary Number There are only 0 and 1 (cid:190) Systems These two binary digits are commonly (cid:190) referred to as bits Department of Computer Science and Information Engineering HANEL National Cheng Kung University, TAIWAN 3 Divide the decimal number by 2 (cid:137) NUMBERING repeatedly AND CODING Keep track of the remainders SYSTEMS (cid:137) Continue this process until the quotient (cid:137) Converting becomes zero from Decimal Write the remainders in reverse order (cid:137) to Binary to obtain the binary number Ex. Convert 25 to binary 10 Quotient Remainder 25/2 = 12 1 LSB (least significant bit) 12/2 = 6 0 6/2 = 3 0 3/2 = 1 1 1/2 = 0 1 MSB (most significant bit) Therefore 25 = 11001 10 2 Department of Computer Science and Information Engineering HANEL National Cheng Kung University, TAIWAN 4 Know the weight of each bit in a binary (cid:137) NUMBERING number AND CODING Add them together to get its decimal (cid:137) SYSTEMS equivalent Converting Ex. Convert 11001 to decimal 2 from Binary to Weight: 24 23 22 21 20 Decimal Digits: 1 1 0 0 1 Sum: 16 + 8 + 0 + 0 + 1 = 25 10 Use the concept of weight to convert a (cid:137) decimal number to a binary directly Ex. Convert 39 to binary 10 32 + 0 + 0 + 4 + 2 + 1 = 39 Therefore, 39 = 100111 10 2 Department of Computer Science and Information Engineering HANEL National Cheng Kung University, TAIWAN 5 Base 16, the (cid:137) NUMBERING hexadecimalsystem, AND CODING Decimal Binary Hex is used as a 0 0000 0 SYSTEMS 1 0001 1 convenient 2 0010 2 Hexadecimal representation of 3 0011 3 4 0100 4 System binary numbers 5 0101 5 ex. 6 0110 6 (cid:190) 7 0111 7 It is much easier to 8 1000 8 represent a string of 0s 9 1001 9 and 1s such as 10 1010 A 100010010110 as its 11 1011 B hexadecimal equivalent of 12 1100 C 896H 13 1101 D 14 1110 E 15 1111 F Department of Computer Science and Information Engineering HANEL National Cheng Kung University, TAIWAN 6 To represent a binary number as its (cid:137) NUMBERING equivalent hexadecimal number AND CODING Start from the right and group 4 bits at a (cid:190) SYSTEMS time, replacing each 4-bit binary number with its hex equivalent Converting Ex. Represent binary 100111110101 in hex between Binary and Hex 1001 1111 0101 = 9 F 5 To convert from hex to binary (cid:137) Each hex digit is replaced with its 4-bit (cid:190) binary equivalent Ex. Convert hex 29B to binary 2 9 B = 0010 1001 1011 Department of Computer Science and Information Engineering HANEL National Cheng Kung University, TAIWAN 7 Convert to binary first and then (cid:137) NUMBERING convert to hex AND CODING Convert directly from decimal to hex SYSTEMS (cid:137) by repeated division, keeping track of Converting the remainders from Decimal to Hex Ex. Convert 45 to hex 10 32 16 8 4 2 1 1 0 1 1 0 1 32 + 8 + 4 + 1 = 45 45 = 0010 1101 = 2D 10 2 16 Ex. Convert 629 to hex 10 512 256 128 64 32 16 8 4 2 1 1 0 0 1 1 1 0 1 0 1 629 = 512+64+32+16+4+1 = 0010 0111 0101 = 275 10 2 16 Department of Computer Science and Information Engineering HANEL National Cheng Kung University, TAIWAN 8