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Waveform Generator Assembly Code

The document contains code for generating and displaying different waveforms on an LCD screen. It initializes the LCD, displays text, and contains subroutines for generating sine waves, square waves, sawtooth waves, and triangular waves at frequencies of 50Hz, 100Hz, 250Hz, and 500Hz. It also contains subroutines for blinking the displayed frequency on the screen.

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Mian Fahim
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© © All Rights Reserved
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331 views17 pages

Waveform Generator Assembly Code

The document contains code for generating and displaying different waveforms on an LCD screen. It initializes the LCD, displays text, and contains subroutines for generating sine waves, square waves, sawtooth waves, and triangular waves at frequencies of 50Hz, 100Hz, 250Hz, and 500Hz. It also contains subroutines for blinking the displayed frequency on the screen.

Uploaded by

Mian Fahim
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as TXT, PDF, TXT or read online on Scribd
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org 0000h

mov sp,#40h
mov r3,#00h
mov r4,#00h

lcall DELAY_20MS ; to give lcd some time to get started

mov a,#38h ; Initialization for LCD


lcall command
lcall DELAY

mov a,#0ch ; Screen on and cursor off, no blink


lcall command
lcall DELAY

mov a,#06h ; shift cursor right


lcall command
lcall DELAY

mov a,#01h ; Clear screen and home cursor


lcall command
lcall DELAY

mov a,#'S' ;Write "SINE WAVE"


lcall display
lcall DELAY

mov a,#'I'
lcall display
lcall DELAY

mov a,#'N'
lcall display
lcall DELAY

mov a,#'E'
lcall display
lcall DELAY

mov a,#' '


lcall display
lcall DELAY

mov a,#'W'
lcall display
lcall DELAY

mov a,#'A'
lcall display
lcall DELAY

mov a,#'V'
lcall display
lcall DELAY

mov a,#'E'
lcall display
lcall DELAY
mov a,#0C0h ; shift cursor to second line
lcall command
lcall DELAY

mov a,#'5' ;Write "50 Hz" on second line


lcall display
lcall DELAY

mov a,#'0'
lcall display
lcall DELAY

mov a,#' '


lcall display
lcall DELAY

mov a,#'H'
lcall display
lcall DELAY

mov a,#'z'
lcall display
lcall DELAY

SINE_50:mov b,#200 ;subroutine for generating 50 Hz sinewave


mov dptr,#SINE_TABLE
L3:clr a
movc a,@a+dptr
mov p2,a
inc dptr
lcall DELAY_42US
djnz b,L3
lcall CHECK_GLOBLE
sjmp SINE_50

SINE_100:mov b,#200 ;subroutine for generating 100 Hz sinewave


mov dptr,#SINE_TABLE
L4:clr a
movc a,@a+dptr
mov p2,a
inc dptr
lcall DELAY_19US
djnz b,L4
lcall CHECK_GLOBLE
sjmp SINE_100
SINE_250:mov b,#200 ;subroutine for generating 250 Hz sinewave
mov dptr,#SINE_TABLE
L5:clr a
movc a,@a+dptr
mov p2,a
inc dptr
lcall DELAY_4US
djnz b,L5
lcall CHECK_GLOBLE
sjmp SINE_250
SINE_500:mov b,#200 ;subroutine for generating 500 Hz sinewave
mov dptr,#SINE_TABLE
L6:clr a
movc a,@a+dptr
mov p2,a
inc dptr
nop
djnz b,L6
lcall CHECK_GLOBLE
sjmp SINE_500
SQURE_50:clr a ;subroutine for generating 50 Hz squrewave
mov p2,a
lcall DELAY_10MS
cpl a
mov p2,a
lcall DELAY_10MS
lcall CHECK_GLOBLE
sjmp SQURE_50
SQURE_100:clr a ;subroutine for generating 100 Hz squrewave
mov p2,a
lcall DELAY_5MS
cpl a
mov p2,a
lcall DELAY_5MS
lcall CHECK_GLOBLE
sjmp SQURE_100
SQURE_250:clr a ;subroutine for generating 250 Hz squrewave
mov p2,a
lcall DELAY_2MS
cpl a
mov p2,a
lcall DELAY_2MS
lcall CHECK_GLOBLE
sjmp SQURE_250
SQURE_500:clr a ;subroutine for generating 500 Hz squrewave
mov p2,a
lcall DELAY_1MS
cpl a
mov p2,a
lcall DELAY_1MS
lcall CHECK_GLOBLE
sjmp SQURE_500
SAWTOOTH_50:clr a ;subroutine for generating 50 Hz
sawtoothwave
L7:mov p2,a
lcall DELAY_27US
inc a
lcall CHECK_GLOBLE
sjmp L7
SAWTOOTH_100:clr a ;subroutine for generating 100 Hz
sawtoothwave
L8:mov p2,a
lcall DELAY_8US
inc a
lcall CHECK_GLOBLE
sjmp L8
SAWTOOTH_250:clr a ;subroutine for generating 250 Hz
sawtoothwave
L9:mov p2,a
lcall DELAY_5US
inc a
cjne a,#200,L9
lcall CHECK_GLOBLE
sjmp SAWTOOTH_250
SAWTOOTH_500:clr a ;subroutine for generating 500 Hz
sawtoothwave
L10:mov p2,a
nop
nop
nop
inc a
cjne a,#250,L10
lcall CHECK_GLOBLE
sjmp SAWTOOTH_500
TRIANGULAR_50:clr a ;subroutine for generating 50 Hz
triangularhwave
L11:mov p2,a
lcall DELAY_15US
inc a
cjne a,#0ffh,L11
L12:dec a
mov p2,a
lcall DELAY_15US
cjne a,#00h,L12
lcall CHECK_GLOBLE
sjmp TRIANGULAR_50
TRIANGULAR_100:clr a ;subroutine for generating 100 Hz
triangularhwave
L13:mov p2,a
lcall DELAY_5US
inc a
cjne a,#0ffh,L13
L14:dec a
mov p2,a
lcall DELAY_5US
cjne a,#00h,L14
lcall CHECK_GLOBLE
sjmp TRIANGULAR_100
TRIANGULAR_250:clr a ;subroutine for generating 250 Hz
triangularhwave
L15:mov p2,a
nop
nop
nop
inc a
cjne a,#0ffh,L15
L16:dec a
mov p2,a
nop
nop
nop
cjne a,#00h,L16
lcall CHECK_GLOBLE
sjmp TRIANGULAR_250
TRIANGULAR_500:clr a ;subroutine for generating 500 Hz
triangularhwave
L17:mov p2,a
inc a
cjne a,#0ffh,L17
L18:dec a
mov p2,a
cjne a,#00h,L18
lcall CHECK_GLOBLE
sjmp TRIANGULAR_500

FREQ_50B:mov r4,#00h ;subroutine to make blink "50 Hz"


mov r7,#10
mov b,#06h

mov a,#0C0h
lcall command
lcall DELAY
M0:mov a,#' ' ;to blank first line
lcall display
lcall DELAY
djnz b,M0

L19:mov a,#0C0h
lcall command
lcall DELAY

mov a,#'5'
lcall display
lcall DELAY

mov a,#'0'
lcall display
lcall DELAY

mov a,#' '


lcall display
lcall DELAY

mov a,#'H'
lcall display
lcall DELAY

mov a,#'z'
lcall display
lcall DELAY

lcall DELAY_01S
lcall CHECK1
dec r7
cjne r7,#00h,L21
ljmp GENERATE

L21:mov a,#0C0h
lcall command
lcall DELAY
mov b,#06h

L22:mov a,#' '


lcall display
lcall DELAY
djnz b,L22
lcall DELAY_01S
ljmp L19
CHECK1:mov p0,#0ffh ;subroutine to check key press position
mov a,p0
cjne a,#7fh,NEXT9
ljmp FREQ_CHECK
NEXT9:cjne a,#0bfh,NEXT10
ljmp WAVE_CHECK
NEXT10:cjne a,#0dfh,NEXT12
inc r4
cjne r4,#04h,next11
mov r4,#00h
NEXT11:ljmp FREQ_CHECK
NEXT12:cjne a,#0efh,NEXT14
dec r4
cjne r4,#0ffh,NEXT13
mov r4,#03h
NEXT13:ljmp FREQ_CHECK
NEXT14:cjne a,#0f7h,NEXT15
ljmp GENERATE
NEXT15:ret

FREQ_100B:mov r4,#01h ;subroutine to make blink "100 Hz"


mov r7,#10
L23:mov a,#0C0h
lcall command
lcall DELAY

mov a,#'1'
lcall display
lcall DELAY

mov a,#'0'
lcall display
lcall DELAY

mov a,#'0'
lcall display
lcall DELAY

mov a,#' '


lcall display
lcall DELAY

mov a,#'H'
lcall display
lcall DELAY

mov a,#'z'
lcall display
lcall DELAY

lcall DELAY_01S
lcall CHECK1
dec r7
cjne r7,#00h,L25
ljmp GENERATE

L25:mov a,#0C0h
lcall command
lcall DELAY
mov b,#06h
L26:mov a,#' '
lcall display
lcall DELAY
djnz b,L26
lcall DELAY_01S
ljmp L23

FREQ_250B:mov r4,#02h ;subroutine to make blink "250 Hz"


mov r7,#10
L27:mov a,#0C0h
lcall command
lcall DELAY

mov a,#'2'
lcall display
lcall DELAY

mov a,#'5'
lcall display
lcall DELAY

mov a,#'0'
lcall display
lcall DELAY

mov a,#' '


lcall display
lcall DELAY

mov a,#'H'
lcall display
lcall DELAY

mov a,#'z'
lcall display
lcall DELAY
lcall DELAY_01S
lcall CHECK1
dec r7
cjne r7,#00h,L29
ljmp GENERATE
L29:mov a,#0C0h
lcall command
lcall DELAY
mov b,#06h

L30:mov a,#' '


lcall display
lcall DELAY
djnz b,L30
lcall DELAY_01S
ljmp L27
FREQ_500B:mov r4,#03h ;subroutine to make blink "500 Hz"
mov r7,#10
L31:mov a,#0C0h
lcall command
lcall DELAY

mov a,#'5'
lcall display
lcall DELAY

mov a,#'0'
lcall display
lcall DELAY

mov a,#'0'
lcall display
lcall DELAY

mov a,#' '


lcall display
lcall DELAY

mov a,#'H'
lcall display
lcall DELAY

mov a,#'z'
lcall display
lcall DELAY
lcall DELAY_01S
lcall CHECK1
dec r7
cjne r7,#00h,L33
ljmp GENERATE

L33:mov a,#0C0h
lcall command
lcall DELAY
mov b,#06h

L34:mov a,#' '


lcall display
lcall DELAY
djnz b,L34
lcall DELAY_01S
ljmp L31

WAVE_SINEB:mov r3,#00h ;subroutine to make blink "SINE WAVE"


mov r7,#10
mov b,#0fh

mov a,#80h
lcall command
lcall DELAY

M1:mov a,#' ' ;get first line blank


lcall display
lcall DELAY
djnz b,M1

L35:mov a,#80h
lcall command
lcall DELAY

mov a,#'S'
lcall display
lcall DELAY

mov a,#'I'
lcall display
lcall DELAY

mov a,#'N'
lcall display
lcall DELAY

mov a,#'E'
lcall display
lcall DELAY

mov a,#' '


lcall display
lcall DELAY

mov a,#'W'
lcall display
lcall DELAY

mov a,#'A'
lcall display
lcall DELAY

mov a,#'V'
lcall display
lcall DELAY

mov a,#'E'
lcall display
lcall DELAY
lcall CHECK2
dec r7
cjne r7,#00h,L37
ljmp GENERATE

L37:mov a,#80h
lcall command
lcall DELAY
mov b,#09h

L38:mov a,#' '


lcall display
lcall DELAY
djnz b,L38
ljmp L35

WAVE_SAWTOOTHB:mov r3,#01h ;subroutine to make blink "SAWTOOTH WAVE"


mov r7,#10
mov b,#0fh

mov a,#80h
lcall command
lcall DELAY

M2:mov a,#' '


lcall display
lcall DELAY
djnz b,M2

L39:mov a,#80h
lcall command
lcall DELAY

mov a,#'S'
lcall display
lcall DELAY

mov a,#'A'
lcall display
lcall DELAY

mov a,#'W'
lcall display
lcall DELAY

mov a,#'T'
lcall display
lcall DELAY

mov a,#'O'
lcall display
lcall DELAY

mov a,#'O'
lcall display
lcall DELAY

mov a,#'T'
lcall display
lcall DELAY

mov a,#'H'
lcall display
lcall DELAY

mov a,#' '


lcall display
lcall DELAY

mov a,#'W'
lcall display
lcall DELAY

mov a,#'A'
lcall display
lcall DELAY

mov a,#'V'
lcall display
lcall DELAY

mov a,#'E'
lcall display
lcall DELAY

lcall CHECK2
dec r7
cjne r7,#00h,L41
ljmp GENERATE

L41:mov a,#80h
lcall command
lcall DELAY
mov b,#14

L42:mov a,#' '


lcall display
lcall DELAY
djnz b,L42
ljmp L39

WAVE_TRIANGULARB:mov r3,#02h ;subroutine to make blink "TRIANGULAR


WAVE"
mov r7,#10

L43:mov a,#80h
lcall command
lcall DELAY

mov a,#'T'
lcall display
lcall DELAY

mov a,#'R'
lcall display
lcall DELAY

mov a,#'I'
lcall display
lcall DELAY

mov a,#'A'
lcall display
lcall DELAY

mov a,#'N'
lcall display
lcall DELAY

mov a,#'G'
lcall display
lcall DELAY

mov a,#'U'
lcall display
lcall DELAY

mov a,#'L'
lcall display
lcall DELAY

mov a,#'A'
lcall display
lcall DELAY

mov a,#'R'
lcall display
lcall DELAY

mov a,#' '


lcall display
lcall DELAY

mov a,#'W'
lcall display
lcall DELAY

mov a,#'A'
lcall display
lcall DELAY

mov a,#'V'
lcall display
lcall DELAY

mov a,#'E'
lcall display
lcall DELAY
lcall CHECK2
dec r7
cjne r7,#00h,L45
ljmp GENERATE

L45:mov a,#80h
lcall command
lcall DELAY
mov b,#15

L46:mov a,#' '


lcall display
lcall DELAY
djnz b,L46
ljmp L43

WAVE_SQUREB:mov r3,#03h ;subroutine to make blink "SQURE WAVE"


mov r7,#10
mov b,#0fh

mov a,#80h
lcall command
lcall DELAY

M3:mov a,#' '


lcall display
lcall DELAY
djnz b,M3

L47:mov a,#80h
lcall command
lcall DELAY

mov a,#'S'
lcall display
lcall DELAY

mov a,#'Q'
lcall display
lcall DELAY

mov a,#'U'
lcall display
lcall DELAY

mov a,#'R'
lcall display
lcall DELAY

mov a,#'E'
lcall display
lcall DELAY

mov a,#' '


lcall display
lcall DELAY

mov a,#'W'
lcall display
lcall DELAY

mov a,#'A'
lcall display
lcall DELAY

mov a,#'V'
lcall display
lcall DELAY

mov a,#'E'
lcall display
lcall DELAY
lcall CHECK2
dec r7
cjne r7,#00h,L49
ljmp GENERATE
L49:mov a,#80h
lcall command
lcall DELAY
mov b,#10

L50:mov a,#' '


lcall display
lcall DELAY
djnz b,L50
ljmp L47

CHECK2:mov p0,#0ffh ;subroutine to check key press position


mov a,p0
cjne a,#0f7h,NEXT16
ljmp FREQ_CHECK
NEXT16:cjne a,#0fbh,NEXT17
ljmp WAVE_CHECK
NEXT17:cjne a,#0fdh,NEXT19
inc r3
cjne r3,#04h,next18
mov r3,#00h
NEXT18:ljmp WAVE_CHECK
NEXT19:cjne a,#0feh,NEXT21
dec r3
cjne r3,#0ffh,NEXT20
mov r3,#03h
NEXT20:ljmp WAVE_CHECK
NEXT21:cjne a,#07fh,NEXT22
ljmp GENERATE
NEXT22:ret

GENERATE:cjne r3,#00h,NEXT23 ;subroutine to generate selected waveform


ljmp L51
NEXT23:cjne r3,#01h,NEXT24
ljmp L52
NEXT24:cjne r3,#02h,NEXT25
ljmp L53
NEXT25:ljmp L54

L51:cjne r4,#00h,NEXT26
ljmp SINE_50
NEXT26:cjne r4,#01h,NEXT27
ljmp SINE_100
NEXT27:cjne r4,#02h,NEXT28
ljmp SINE_250
NEXT28:ljmp SINE_500

L52:cjne r4,#00h,NEXT29
ljmp SAWTOOTH_50
NEXT29:cjne r4,#01h,NEXT30
ljmp SAWTOOTH_100
NEXT30:cjne r4,#02h,NEXT31
ljmp SAWTOOTH_250
NEXT31:ljmp SAWTOOTH_500

L53:cjne r4,#00h,NEXT32
ljmp TRIANGULAR_50
NEXT32:cjne r4,#01h,NEXT33
ljmp TRIANGULAR_100
NEXT33:cjne r4,#02h,NEXT34
ljmp TRIANGULAR_250
NEXT34:ljmp TRIANGULAR_500

L54:cjne r4,#00h,NEXT35
ljmp SQURE_50
NEXT35:cjne r4,#01h,NEXT36
ljmp SQURE_100
NEXT36:cjne r4,#02h,NEXT37
ljmp SQURE_250
NEXT37:ljmp SQURE_500

WAVE_CHECK:cjne r3,#00h,NEXT1
ljmp WAVE_SINEB
NEXT1:cjne r3,#01h,NEXT2
ljmp WAVE_SAWTOOTHB
NEXT2:cjne r3,#02h,NEXT3
ljmp WAVE_TRIANGULARB
NEXT3:ljmp WAVE_SQUREB

FREQ_CHECK:cjne r4,#00h,NEXT4
ljmp FREQ_50B
NEXT4:cjne r4,#01h,NEXT5
ljmp FREQ_100B
NEXT5:cjne r4,#02h,NEXT6
ljmp FREQ_250B
NEXT6:ljmp FREQ_500B

CHECK_GLOBLE:mov p0,#0ffh
mov a,p0
cjne a,#0f7h,NEXT7 ; first key pressed freq check
ljmp FREQ_CHECK
NEXT7:cjne a,#0fbh,NEXT8 ; second key pressed w/f check
ljmp WAVE_CHECK
NEXT8:ret

DELAY_01S: mov r1,#250 ;subrotine to generate 0.1sec delay


A6:mov r2,#200
djnz r2,$
djnz r1,A6
ret
DELAY_5US:mov r0,#5 ;subrotine to generate 10us delay
djnz r0,$
ret
DELAY_15US:mov r0,#15 ;subrotine to generate 30us delay
djnz r0,$
ret
DELAY_27US:mov r0,#27 ;subrotine to generate 54us delay
djnz r0,$
ret
DELAY_8US:mov r0,#8 ;subrotine to generate 16us delay
djnz r0,$
ret
DELAY_10MS:mov r0,#20 ;subrotine to generate 10ms delay
A2:mov r1,#250
djnz r1,$
djnz r0,A2
ret
DELAY_5MS:mov r0,#10 ;subrotine to generate 5ms delay
A3:mov r1,#250
djnz r1,$
djnz r0,A3
ret
DELAY_2MS:mov r0,#4 ;subrotine to generate 2ms delay
A4:mov r1,#250
djnz r1,$
djnz r0,A4
ret
DELAY_1MS:mov r0,#2 ;subrotine to generate 1ms delay
A5:mov r1,#250
djnz r1,$
djnz r0,A5
ret
DELAY_42US:mov r0,#42 ;subrotine to generate 84us delay
djnz r0,$
ret
DELAY_19US:mov r0,#19 ;subrotine to generate 19us delay
djnz r0,$
ret
DELAY_4US:mov r0,#4 ;subrotine to generate 4us delay
djnz r0,$
ret

command:
lcall ready ; Write when display not busy
mov p1,a ; Command character in P1
clr p3.5 ; Command resister chosen
clr p3.3 ; Write enabled
setb p3.4 ; Strobe character to display
clr p3.4
ret
ready:
clr p3.4 ; Display disabled
mov p1,#0ffh ; Configure P1 for input
clr p3.5 ; Select command register
setb p3.3 ; Read enabled
wait:
clr p3.4 ; Strobe display
setb p3.4 ; Read busy status of display
jb p1.7,wait ; Wait for not busy (BF = 0)
clr p3.4 ; End display strobe
ret
display:
lcall ready ; Write when display ready
mov P1,a ; Data character in P1
setb p3.5 ; Data resister chosen
clr p3.3 ; write enabled
setb p3.4 ; Strobe character to display
clr P3.4
ret

DELAY: MOV R0,#90 ;50 or higher for fast CPUs


HERE2: MOV R1,#255 ;R1=255
HERE1: DJNZ R1,HERE1 ;stay until R1 becomes 0
DJNZ R0,HERE2
RET

DELAY_20MS:mov r1,#40
A1:mov r0,#250
djnz r0,$
djnz r1,A1
ret

SINE_TABLE:db
127,131,135,139,143,147,151,154,159,163,167,170,174,178,181,185,189,192,196,199,202
,205,209,212,215,218,220,223,226,228,231,233,235,237,239,241,243,244,246,247,249,25
0,251,252,253,253,254,254,255,255,255
db
255,255,254,254,253,253,252,251,250,249,247,246,244,243,241,239,237,235,233,231,228
,226,223,220,218,215,212,209,205,202,199,196,192,189,185,181,178,174,170,167,163,15
9,154,151,147,143,139,135,131,127
db
123,119,115,111,107,103,100,95,91,87,84,80,76,73,69,65,62,58,55,52,49,45,42,39,36,3
4,31,28,26,23,21,19,17,15,13,11,10,8,7,5,4,3,2,1,1,1,0,0,0,0
db
0,0,0,0,1,1,1,2,3,4,5,7,8,10,11,13,15,17,19,21,23,26,28,31,34,36,39,42,45,49,52,55,
58,62,65,69,73,76,80,84,87,91,95,100,103,107,111,115,119,123

end

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