System & Program Developments of 8051

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Code Syntax Assembly Language Programming Tools & Techniques for Program Development The

1 System & Program Developments of 8051 Program Structure and Design Introduction Advantages and Disadvantages of Structured Programming The Three Structures: statements, loops, choice Pseudo Code Syntax Assembly Language Programming Tools & Techniques for Program Development The Development Cycle Integration and Verification Command and Environments 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 1

2 Introduction Structured Programming: Organizing and coding programs that reduces complexity, improves clarity, and facilitates debugging and modifying All programs may be written using only three structures: statements, loops, and choice too good to be true. Introduce Structure programming to assembly language programming Flowcharts Pseudo code Assembly language 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 2

3 Flowcharts Decision block Off-page connector Process box Input/Output block Predefined process (subroutine) Program flow arrow Program terminator 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 3

4 Pseudo Code Strict adherence to structure in combination with informal language [get a character from the keyboard] IF [condition is true] THEN [do statement 1] ELSE BEGIN [do statement 2] [do statement 3] END 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 4

5 Advantages & Disadvantages of Structured Programming Advantages: Simple to trace, debug Finite number of structures Structures as building block The set of structure is complete Structures are self-documenting, easy to read Structures are easy to describe in flowcharts, syntax diagrams, pseudo code,.. Increased program productivity 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 5

6 Advantages & Disadvantages of Structured Programming Disadvantages: Only a few high-level languages (Pascal, C, PL/M) accept the structures directly; others require extra translation stage Structured program may execute slower and require more memory Some problems (a minority) are more difficult to solve using only the three structures Nested structures can be difficult to follow 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 6

7 The Three Structures Statements [count = 0] PRINT_STRING( Select Option: ) Loops (iteration) WHILE/DO REPEAT/UNTIL Choice IF/THEN/ELSE CASE 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 7

8 The WHILE/DO Statement WHILE [condition] DO [statement] (statement might not be performed at all!) Enter WHILE [c == 1] DO [statement] Condition True? Yes Statement No Exit ENTER: JNC EXIT STATEMENT: (statement) JMP ENTER EXIT: (continue) 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 8

9 WHILE/DO: SUM Subroutine [sum (A) = 0] WHILE [length (R7) > 0] DO BEGIN [sum = sum (R0)] [increment pointer] [decrement length] END 8051 code (closely structured; 13 bytes) SUM: CLR A LOOP: CJNZ R7,#0,STAM JMP EXIT STAM: ADD A,@R0 INC R0 DEC R7 JMP LOOP: EXIT: RET (loosely structured; 9 bytes) SUM: CLR A INC R7 MORE: DJNZ R7,SKIP RET SKIP: ADD A,@R0 INC R0 SJMP MORE 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 9

10 WHILE/DO Pseudo code: WHILE [ACC!= CR AND R7!= 0] DO [statement] Enter ACC!= <CR>? Yes R7!= 0? Yes Statement No No Exit 8051 code: ENTER: CJNE A,#0DH,SKIP JMP EXIT SKIP: CJNE R7,#0,STAM JMP EXIT STAM: (one or more statements).. JMP ENTER EXIT: (continue) 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 10

11 The REPEAT/UNTIL Statement REPEAT [statement] UNTIL [condition] (statement performed at least once) Enter REPEAT [statement] UNTIL [c == 1] Statement No Condition True? Yes Exit ENTER: (statement) JNC ENTER EXIT: (continue) 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 11

12 The REPEAT/UNTIL Statement REPEAT [ACC [increment pointer] UNTIL [ACC == Z or ACC == 0] Enter 8051 code: Get a char Inc pointer Yes Char = Z? Exit No Char = 0? No Yes STAM: MOV A,@R0 INC R0 JZ EXIT CJNE A,# Z,STAM EXIT: RET 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 12

13 The IF/THEN/ELSE Statement IF [condition] THEN [statement 1] ELSE [statement 2] Enter No condition true? Yes Statement 2 Statement 1 Exit 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 13

14 The IF/THEN/ELSE Statement [input character] IF [input character == graphic] THEN [echo character] ELSE [echo. ] No Echo. Enter Input character Graphic char? Exit Yes Echo char 8051 code: (closely structured; 14 bytes) ENTER: ACALL INCH ACALL ISGRPH JNC STMENT2 STMENT1: ACALL OUTCH JMP EXIT STMENT2: MOV A,#. ACALL OUTCH EXIT: (continue) (loosely structured; 10 bytes) ACALL INCH ACALL ISGRPH JC SKIP MOV A,#. SKIP: ACALL OUTCH (continue) 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 14

15 The CASE Statement Enter CASE [expression] OF 0: [statement 0] 1: [statement 1] 2: [statement 2].. N: [statement 0] [default] END_CASE expression 0? No expression 1? No expression 2? No expression n? No Yes Yes Yes Yes Statement 0 Statement 1 Statement 2 Statement n default Exit 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 15

16 The CASE Statement [input a character] Enter Input character CASE [character] OF 0 : [statement 0] 1 : [statement 1] 2 : [statement 2] 3 : [statement 3] END_CASE char == 0? No char == 1? No char == 2? No char == 3? No Yes Yes Yes Yes Action 0 Action 1 Action 2 Action 3 Exit 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 16

17 The CASE Statement 8051 code: (closely structured) ACALL INCH CJNE A,# 0,SKIP1 ACT0:.. JMP EXIT SKIP1: CJNE A,# 1,SKIP2 ACT1:.. JMP EXIT SKIP2: CJNE A,# 2,SKIP3 ACT2:.. JMP EXIT SKIP3: CJNE A,# 3,EXIT ACT3:.. EXIT: (continue) (loosely structured) ACALL INCH ANL A,#3 ;reduce to 3 bits RL A MOV DPTR,#TABLE TABLE: AJMP ACT0 AJMP ACT1 AJMP ACT2 ACT3:.. JMP EXIT ACT0:.. JMP EXIT ACT1:.. JMP EXIT ACT2:.. EXIT: (continue) 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 17

18 The GOTO Statement GOTO statement can always be avoided by using the structures. Sometimes GOTO statement provides an easy method of terminating a structure when errors occur. GOTO statements usually becomes unconditional jump in assembly implementation. Extreme caution is needed. Never exit a subroutine using GOTO instead of normal return for the return address will be left on the stack and eventually stack overflow will occur. 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 18

19 Pseudo Code Syntax Tips of using pseudo code: Use descriptive language for statements Avoid machine dependency in statements Enclose conditions & statements in brackets: [] Begin all subroutines with their names followed by a set of parameters: () End all subroutine with RETURN () Use lower text except reserved words & subroutine names Indent all statements from the structure entry points and exit points Use the commercial at sign (@) for indirect addressing 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 19

20 Suggested Pseudo Code Syntax Reserved words: BEGIN END REPEAT UNTIL WHILE DO IF THEN ELSE CASE OF RETURN Arithmetic operators: + addition - subtraction * multiplication / division % modulus (remainder after division) 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 20

21 Suggested Pseudo Code Syntax Relational operators: == true if values equal to each other!= true if values not equal to each other < true if first value less than second <= true if first value <= second > true if first value > second >= true if first value >= second && true if both values are true true if either value is true Bitwise Logical operators: & logical AND logical OR ^ logical XOR ~ logical NOT (one s complement) >> logical shift right << logical shift left 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 21

22 Suggested Pseudo Code Syntax Assignment operators: = set equal to op = assign operator shorthand where op is one of + - * / % << >> & ^ Precedence operators: ( ) Indirect 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 22

23 Suggested Pseudo Code Syntax Operator Precedence: ( ) * / % + - << >> < <= > >= ==!= & ^ && = += -= *= /= etc 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 23

24 Suggested Pseudo Code Syntax Structures: Statement: [do something] Statement block: BEGIN [statement] [statement] END WHILE/DO: WHILE [condition] DO [statement] 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 24

25 Suggested Pseudo Code Syntax REPEAT/UNTIL: REPEAT [statement] UNTIL [condition] IF/THEN/ELSE: IF [condition] THEN [statement 1] (ELSE [statement 2]) CASE/OF: CASE [expression] OF 1: [statement 1] 2: [statement 2] 3: [statement 3].. n: [statement n] [default] END 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 25

26 Assembly Language Programming Labels Use labels that are descriptive of the destination they represent Comments Use comments wherever possible Comment conditional jump instructions using a question similar to the flowchart Comment Blocks At the beginning of each subroutine: name of the sub, operations, entry conditions, exit conditions, name of other subroutines used, name of registers affected, etc. 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 26

27 INLINE SUBROUTINE EXAMPLE ;*************************************************************************************** ; ;INLINE INPUT LINE OF CHARACTERS ; LINE MUST END WITH <CR> ; MAXIMUM LENGTH 31 CHARACTERS INCLUDE <CR> ; ;ENTER: NO CONDITIONS ;EXIT: ASCII CODES IN INTERNAL DATA RAM ; 0 STORED AT END OF LINE ;USES INCHAR, OUTCHR ; ;**************************************************************************************** INLINE: PUSH 00H ;SAVE R0 ON STACK PUSH 07H ;SAVE R7 ON STACK PUSH ACC ;SAVE ACCUMULATOR MOV R0,#60H ;SET UP BUFFER AT 60H MOV R7,#31 ;MAX LENGTH OF LINE STMENT: ACALL INCHAR ;INPUT A CHARACTER ACALL OUTCHR ;ECHO TO CONSOLE ;STORE IN BUFFER 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 27

28 INLINE SUBROUTINE EXAMPLE INLINE: PUSH 00H ;SAVE R0 ON STACK PUSH 07H ;SAVE R7 PUSH ACC ;SAVE ACCUMULATOR MOV R0,#60H ;SET UP BUFFER AT 60H MOV R7,#31 ;MAX LENGTH OF LINE STMENT: ACALL INCHAR ;INPUT A CHARACTER ACALL OUTCHR ;ECHO TO CONSOLE ;STORE IN BUFFER INC R0 ;INC BUFFER POINTER DEC R7 ;DEC LENGTH COUNTER CJNE A,#0DH, SKIP ;IS CHAR = <CR>? SJMP EXIT ;YES, EXIT SKIP: CJNE R7,#0,STMENT ;NO, GET ANOTHER CHAR EXIT: ;END WITH NULL CHAR POP ACC ;RESTORE REGISTERS FROM POP 07H ;STACK POP 00H RET 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 28

29 INLINE SUBROUTINE EXAMPLE ;******************************************************************************************** ; INCHR - INput CHaRacter from serial port ; enter: no condition ; exit: ASCII code in ACC.0 to ACC.6; ACC.7 cleared; ctrl-c aborts ; to prompt ;******************************************************************************************** INCHR: JB X13_BIT,IN1 ;if x13 installed, use interrupt flag RI JNB r_flag,$ ;wait for receive_flag to be set CLR ET1 ;begin critical section CLR r_flag ;>>> clear receive_flag and MOV A,r_buff ;>>> read receive_buffer SETB ET1 ;end critical section SJMP IN2 ; ;if x13 is not installed, test RI flag IN1: JNB RI,$ ;wait for receive interrupt RI CLR RI ;clear RI flag MOV A,SBUF ;done! IN2: CLR ACC.7 ;clear parity bit (o error checking) CJNE A,#ETX, IN3 ;if ctrl-c, JMP GETCMD ;warm start IN3: RET 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 29

30 INLINE SUBROUTINE EXAMPLE ;******************************************************************************************* * ; OUTCHR - OUTput CHaRacter to serial port with odd parity added in ; ACC.7 ; enter: ASCII code in ACC ; exit:. Character written to SBUF; <CR> sent as <CR><LF>; all ; registers intact ;******************************************************************************************* * RSEG EPROM OUTCHR: PUSH A NL: MOV C,P ;if x13 installed, use interrupt flag RI CPL C ;add odd parity MOV ACC.7,C JB X13_BIT,OUT1 ;if x13 installed, use interrupt JNB t_flag,$ ;wait for transmitter ready CLR ET1 ;begin critical section CLR t_flag ;>>> clear flag and MOV t_buff,a ;>>> load data to transmit SETB ET1 ;end critical section SJMP OUT2 ; 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 30

31 INLINE SUBROUTINE EXAMPLE RSEG EPROM OUTCHR: PUSH A NL: MOV C,P CPL C ;add odd parity MOV ACC.7,C JB X13_BIT,OUT1 ;if x13 installed, use interrupt JNB t_flag,$ ;wait for transmitter ready CLR ET1 ;begin critical section CLR t_flag ;>>> clear flag and MOV t_buff,a ;>>> load data to transmit SETB ET1 ;end critical section SJMP OUT2 ; ;if x13 is not installed, test TI flag OUT1: JNB TI,$ ;wait for transmitter ready CLR TI ;clear TI flag MOV SBUF,A ;done! OUT2: CLR ACC.7 ;remove parity bit CJNE A,#CR, OUT3 ;if <CR>? MOV A,#LF ;yes, add <LF> and send it JMP NL ;warm start OUT3: POP A ;no restore A and JNB p_bit,out4 ;check if send to print CALL PCHAR ;yes, send to printer OUT4: RET ;no, done and return 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 31

32 Assembly Language Programming Saving Registers on the Stack Especially for nested subroutine calls, and building complex programs using subroutine building blocks. Avoid changing the working registers when returns. The Use of Equates Defining constants with equates makes programs easier o read and maintain. The Use of Subroutines Divide and Conquer subdivide large and complex operations into small and simple operations. These small and simple operations are programmed as subroutines and used as building blocks of the large complex program. 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 32

33 OUTSTR SUBROUTINE EXAMPLE OUTSTR OUTCHR Enter Enter Get a char From string Char!= 0? Yes OUTCHR Exit No Add odd parity To character TX buffer empty? Yes Clear flag Write character To transmitter No Inc pointer Clear parity bit Exit 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 33

34 OUTSTR SUBROUTINE EXAMPLE Pseudo code for OUTCHR OUTCHR (char) [put odd parity in bit 7] REPEAT [test transmit buffer] UNTIL [buffer empty] [clear transmit buffer empty flag] [move char to transmit buffer] [clear parity bit] RETURN () Pseudo code for OUTSTR OUTSTR (pointer) WHILE [(char 0] BEGIN OUTCHR(char) [increment pointer] END RETURN() 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 34

35 OUTSTR SUBROUTINE EXAMPLE ;**************************************************************************************** ;OUTCHR: OUTPUT A CHAR IN ACC W. ODD PARITY VIA ; SERIAL PORT ;ENTER: NO CONDITION, ASCII CHAR IN ACC ;EXIT: ASCII CODE W. ODD PARITY SENT OUT & ACC.7=0 ;*************************************************************************************** OUTCHR: MOV C,P ;PUT PARITY BIT IN C FLAG CPL C ;CHANGE TO ODD PARITY MOV ACC.7,C ;ADD TO CHAR AGAIN: JNB TI,AGAIN ;TX EMPTY? CLR TI ;YES, CLEAR FLAG AND MOV SBUF,A ;SEND OUT CHARACTER CLR ACC.7 ;STRIP OFF PARITY BIT AND RET ;RETURN ;**************************************************************************************** ;USES OUTCHR ; OUTSTR: MOV A,@DPTR ;GET CHARACTER JZ EXIT ;IF 0, DONE AND EXIT CALL OUTCHR ;OTHERWISE SEND IT INC DPTR ;INC POINTER SJMP OUTSTR 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 35 EXIT: RET

36 Assembly Language Programming Program Organization Equates Initialization instructions Main body of program Subroutines Data constant definitions (DB and DW) RAM data locations defined using the DS directive 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 36

37 Tools & Techniques for Program Development The Development Cycle 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 37

38 Specifying Software User interface: how the user will interact with and control the system Detail system operations below the user level independent of user interface Modularized system function with inter-module communication Interrupt driven, ISR, time-critical subroutine 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 38

39 Designing Software Flowcharts Pseudo code Editing and Translation Assemble time errors checking: syntax errors only 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 39

40 Preliminary Testing Run time errors will not appear until the program is executed by a simulator or in the target system. Debugger a system program that executes a user program for the purpose of finding run-time errors. Debugger can set breakpoints, singlestepping, examine and modify registers, memories, etc. during program execution 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 40

41 Hardware Development Specifying hardware: assign quantitative data to system functions, physical size/weight, CPU speed, memory, I/O ports, optional features, etc. Designing Hardware: breadboarding, wire-wrapping, PCB layout practice makes perfect 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 41

42 Hardware Development Preliminary Testing: Visual checks before power applied Continuity checks ohmmeter check each connecting wire, IC pin to IC pin DC measurements no ICs, DC voltages varied AC measurements IC installed, verify clock signals, and so on Functionality Testing drive RESET w a low f (1 khz) square wave, write test software or monitor program to debug each function of the hardware board 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 42

43 Detailed Steps in the Development Cycle 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 43

44 Integration and Verification Hardware Software Integration test Software Simulation simulator Hardware Emulation hardware emulator or in-circuit emulator (ICE) Execution from RAM effective & simple testing for software in the target system 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 44

45 Intel Hexadecimal Format Field Bytes Description Record mark 1 : indicates start-of-record Record length 2 Number of data bytes in record Load address 4 Start address for data bytes Record type 2 00 = data record; 01 = end record Data bytes 0-16 data Checksum 2 Sum of all bytes in record + checksum = /12/7 T. L. Jong, Dept. of E.E., NTHU 45

46 Intel Hexadecimal Format 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 46

47 Integration and Verification Executing from EPROM firmware burnt in EPROM using EPROM writer Executing from on-chip flash (8952), EPROM (8752), EEPROM, (OTP, MTP) using Universal Programmer/Writer The Factory Mask ROM for mass production Executing from SRAM downloaded from host into the SBC /12/7 T. L. Jong, Dept. of E.E., NTHU 47

48 The Development Environment 2011/12/7 T. L. Jong, Dept. of E.E., NTHU 48

Microcontroller Intel [Instruction Set]

Microcontroller Intel [Instruction Set] Microcontroller Intel 8051 [Instruction Set] Structure of Assembly Language [ label: ] mnemonic [operands] [ ;comment ] Example: MOV R1, #25H ; load data 25H into R1 2 8051 Assembly Language Registers