Published November 19, 2018 © GPL3+

Lissajous Figures on 8x8 LED Matrix

Display dynamic Lissajous figures on an 8x8 LED matrix (or 64 discrete LEDs) with a PIC16F627 microcontroller.

IntermediateFull instructions provided5 hours996

Things used in this project

Hardware components

Microchip PIC16F627

Texas Instruments SN74HC00

Resistor 220 ohm

Story

Watch the video

Lissajous Figures

A point of light oscillating in 2 perpendicular axes draws a pattern named "Lissajous Figure" (1857) or "Bowditch Curve" (1815). Patterns range from simple to complex depending on the frequency ratio and phase of the 2 axes. A 1:1 ratio with 0 phase difference draws a straight line at 45° angle. In this project the frequency ratio of the 2 axes slowly sweeps back and forth between 1:1 and 2:1. These patterns are easily generated with an oscilloscope and 2 sine wave oscillators. In the mid 1800's Joules Antoine Lissajous deflected a light beam with mirrors attached to tuning forks. He also created a SAND PENDULUM. This project displays Lissajous Figures on an 8x8 LED matrix (or 64 discrete LEDs for a larger device) and is driven by a PIC16F627 microcontroller.

Schematic:

PORTB pins of the mcu drive the 8 common anodes (X-axis). PORTA(Y-axis / LED cathodes) has a maximum of 7 pins configurable as outs. To obtain the necessary 8 outs, 2 pins PORTA <1:0> drive a decoder made with 3 nand gates(74HC00) which provides 3 outs from 2 pins of the mcu.

Decoder:

Pattern Table Read:

The "sine" motion of the pixel is obtained by reading a succession of 22 bytepatterns from a table in memory for the X-axis and the Y-axis respectively.

Basic Flowchart:

Link to HEX & ASM codes

Video:

Code

:020000040000FA
:100000008B1307309F008316003085008600831213
:10001000A001A101A6010130A7003F30A2003F309E
:10002000A300271437205E20A40B1228A71C1A282F
:100030000130A500A50B12282608103C031826281D
:100040002608303C031C2628A7142728A7102608BA
:100050003E3A031D2C2827102608013A031D31289B
:10006000271427183528A6033628A60A1228A30B1A
:1000700008003F302607A3002008163A0319452838
:10008000200847208500A00A0800A0010800820778
:10009000FD34FD34FD34FE34FE34FF34F834F434E2
:1000A000EC34BC34BC347C347C347C34BC34BC3460
:1000B000EC34F434F834FF34FE34FE34A20B080080
:1000C0003F30A2002108163A03196B2821086D2041
:1000D0008600A10A0800A10108008207013401344A
:1000E00001340234023404340834103420344034EF
:1000F00040348034803480344034403420341034F0
:08010000083404340234023417
:02400E0070211F
:00000001FF

;####################################
;<<<<<<< LISSAJOUS ART V1.0 >>>>>>>>
;Marcelo Requena 2018 (SimpleTronic)
;####################################


;********************************
;	INIT
;********************************
	processor pic16f627a
	#include <p16f627a.inc>
	__config b'0010000101110000' ;intocc 4mc; portA<6> i/o
	ERRORLEVEL 1	

;******************
;    	INIT
;******************
		cblock	0x20
	loopA
	loopB
	iter
	iter2
	mod1
	mod2
	lfo
	flags ;( flags<0-1> ) 
		endc

#define	BANK_1	bsf STATUS,5
#define	BANK_0	bcf STATUS,5
#define	down	bcf flags,0
#define	up		bsf flags,0


	bcf		INTCON,7 ;disable GIE 
	movlw	B'00000111' ; enable portA i/o - disable comparators
	movwf	CMCON

	BANK_1
	movlw	b'00000000'
	movwf	TRISA
	movwf	TRISB
	BANK_0			;all to out (exc A5)

	clrf	loopA
	clrf	loopB
	clrf	lfo		
	movlw	b'00000001'
	movwf	flags
	movlw	.63
	movwf	iter
	movlw	.63
	movwf	iter2
	up

;***************************************
; Main Program Loop
;***************************************
ploopin
	call	SUB_A		
	call	SUB_B

;loop timer**********************************
	decfsz	mod1	;timer
	goto	ploopin	;timer
	btfss	flags,1 ;skip cycles if set
	goto $+3
	movlw	.1
	movwf	mod2
	decfsz	mod2	;timer
	goto	ploopin	;timer

;speed up cycle *************************
	movfw	lfo
	sublw	.16	; 	16-lfo 
	btfsc	STATUS,C	
	goto	normal	; result lfo= 0-16 continue

	movfw	lfo
	sublw	.48		; 48-lfo 
	btfss	STATUS,C	
	goto	normal	; continue	
	bsf		flags,1	; accel cycle
	goto	more	
normal
	bcf		flags,1	; normal cycle

;Up/Down *********************************
more
	movfw	lfo
	xorlw	.62
	btfss	STATUS,Z	
	goto	$+2
	down

	movfw	lfo
	xorlw	.1
	btfss	STATUS,Z	
	goto	$+2
	up

	btfsc	flags,0
	goto	$+3	
	decf	lfo
	goto	$+2
	incf	lfo
	goto	ploopin

;*************
SUB_A
;*************
	decfsz	iter2
	return			;1	
	movlw	.63		;0
	addwf	lfo,w
	movwf	iter2	

	movfw	loopA	
	xorlw	.22		; is it 22 ?	
	btfsc	STATUS,Z
	goto	$+6		;z=1 is 22 ,reset	
	movfw	loopA   ;z=0 not 22, continue
	call 	SUB_A_TABLE		
	movwf	PORTA	;insert to A	
	incf	loopA
	return
	clrf	loopA
	return			

;*************
SUB_A_TABLE	; port a ; bits <0:1> drive rows 1-2-3
;*************
	addwf	PCL	; w contains offset 1-22

	retlw	b'11111101'	;01 decoder
	retlw	b'11111101'	;01 decoder
	retlw	b'11111101'	;01 decoder
	retlw	b'11111110'	;02 decoder
	retlw	b'11111110'	;02 decoder
	retlw	b'11111111'	;03 decoder
	retlw	b'11111000' ;04
	retlw	b'11110100' ;05
	retlw	b'11101100' ;06
	retlw	b'10111100' ;07 skip A5
	retlw	b'10111100' ;07 skip A5
	retlw	b'01111100' ;08
	retlw	b'01111100' ;08
	retlw	b'01111100' ;08
	retlw	b'10111100' ;07
	retlw	b'10111100' ;07
	retlw	b'11101100' ;06
	retlw	b'11110100' ;05
	retlw	b'11111000' ;04
	retlw	b'11111111'	;03 decoder
	retlw	b'11111110'	;02 decoder
	retlw	b'11111110'	;02 decoder

;*************
SUB_B
;*************
	decfsz	iter
	return			;1	
	movlw	.63	;0
	movwf	iter

	movfw	loopB	
	xorlw	.22		; is it 22 ?	
	btfsc	STATUS,Z
	goto	$+6		;z=1 is 22 , reset	
	movfw	loopB   ;z=0 not 22, continue
	call 	SUB_B_TABLE
	movwf	PORTB	;insert to B	
	incf	loopB
	return
	clrf	loopB
	return	


;*************
SUB_B_TABLE	; port b
;*************
	addwf	PCL	; w contains offset 1-22

	retlw	b'00000001'	;01 
	retlw	b'00000001'	;01 
	retlw	b'00000001'	;01 
	retlw	b'00000010'	;02 
	retlw	b'00000010'	;02 
	retlw	b'00000100'	;03 
	retlw	b'00001000' ;04
	retlw	b'00010000' ;05
	retlw	b'00100000' ;06
	retlw	b'01000000' ;07 
	retlw	b'01000000' ;07 
	retlw	b'10000000' ;08
	retlw	b'10000000' ;08
	retlw	b'10000000' ;08
	retlw	b'01000000' ;07
	retlw	b'01000000' ;07
	retlw	b'00100000' ;06
	retlw	b'00010000' ;05
	retlw	b'00001000' ;04
	retlw	b'00000100'	;03 
	retlw	b'00000010'	;02 
	retlw	b'00000010'	;02 

	end

Credits

SimpleTronic

15 projects • 39 followers

Electronics hobbyist (>55yrs) - Music arranger / composer (>45yrs) - Recording engineer (>25yrs)

Contact

Comments

Please log in or sign up to comment.

Lissajous Figures on 8x8 LED Matrix

Things used in this project

Hardware components

Story

Watch the video

Lissajous Figures

Schematic:

Decoder:

Pattern Table Read:

Basic Flowchart:

Video:

Schematics

Lissajous Figures

Code

lissajous.HEX

lissajous.asm

Credits

SimpleTronic

Comments

Embed the widget on your own site

Lissajous Figures on 8x8 LED Matrix

Lissajous Figures on 8x8 LED Matrix

Things used in this project

Hardware components

Story

Watch the video

Lissajous Figures

Schematic:

Decoder:

Pattern Table Read:

Basic Flowchart:

Video:

Schematics

Lissajous Figures

Code

lissajous.HEX

lissajous.asm

Credits

SimpleTronic

Comments

Related channels and tags