LED AVR

1.1. Turn On/Off LED

In this program you will experiment, how to turn OFF 4 MSB port and turn ON 4 LSB port. To make all Port C function as output, you must send logic '1' to DDRC.

.include "8535def.inc"

start:
     ldi R16,0b11111111
     out DDRC,R16
     ;
     ldi R16,0b11110000
     out PortC,R16
stop:
     rjmp stop
   

1.2. Turn On/Off LED ( single bit )

To set singgle bit of port C as input or output, you have to use SBI ( set bit I/O) to make the bit action as output, or CBI ( clear bit I/O ) to make the bit action as input into DDRC.

.include "8535def.inc"

start:
     sbi DDRC,0 ;PortC, bit 0 as output
     cbi PORTC,0 ;send logic '0' to PortC bit 0
     ;
stop:
     rjmp stop
   

1.3. Turn On/Off LED ( singgle bit )

Another experiment to activate 2 bit port C as output

.include "8535def.inc"
start:
     sbi DDRC,0 ;PortC, bit 0 & 7 as output
     sbi DDRC,7
     cbi PORTC,0 ;send logic '0' to PortC bit 0 & 7
     cbi PORTC,7
     ;
stop:
     rjmp stop

1.4. LED Blink

This experiment will demonstrate how to turn ON and OFF 8 bit on Port C, periodically , using Delay Rutin.

.include "m8535def.inc"
.org 0x0000
     ;
     ldi r16,low(RAMEND)
     out SPL,r16
     ldi r16,high(RAMEND)
     out SPH,r16
     ;
init:
     ldi R16, 0b11111111 ; Make pin PC output
     out DDRC, R16 ;
main:
     ldi R16, 0b00000000 ;
     out PORTC,R16
     rcall delay
     ldi R16, 0b11111111 ;
     out PORTC,R16
     rcall delay
getout:
     rjmp main ;repaet until power removed 

delay:
; provides some delay so that the LED is visible
; =============================
; delay loop
; 499998 cycles: about 1/2 seconds
; -----------------------------
; delaying 499995 cycles:
     ldi R29, $Ff
WGLOOP0:   ldi R30, $ff
WGLOOP1:   ldi R31, $10
WGLOOP2:   dec R31
     brne WGLOOP2
     dec R30
     brne WGLOOP1
     dec R29
     brne WGLOOP0
     ret

1.5. Turn On LED Sequentially

Another experiment to blink a singgle LED

.include "m8535def.inc"
.org 0x0000
     ;
     ldi r16,low(RAMEND)
     out SPL,r16
     ldi r16,high(RAMEND)
     out SPH,r16
     ;
     ldi R16,0b11111111
     out DDRC,R16
main:
     ldi R16,0b11111111
     out PORTC,R16
     rcall delay
     ;
     cbi PORTC,0
     rcall delay
     cbi PORTC,1
     rcall delay
     cbi PORTC,2
     rcall delay
     cbi PORTC,3
     rcall delay
     cbi PORTC,4
     rcall delay
     cbi PORTC,5
     rcall delay
     cbi PORTC,6
     rcall delay
     cbi PORTC,7
     rcall delay
     ;
     rjmp main ; repaet untilpower removed :-)

; provides some delay so that the LED is visible
delay:
     ldi R29, $20
WGLOOP0:   ldi R30, $ff
WGLOOP1:   ldi R31, $ff
WGLOOP2:   dec R31
     brne WGLOOP2
     dec R30
     brne WGLOOP1
     dec R29
     brne WGLOOP0
     ret

1.6. Running LED

Running LED on Port C, start on LSB first

.include "m8535def.inc"
.org 0x0000
     ;
     ldi r16,low(RAMEND)
     out SPL,r16
     ldi r16,high(RAMEND)
     out SPH,r16
     ;
     ldi R16,0b11111111
     out DDRC,R16
     ldi R16,0b11111110
     sec
main:
     out PORTC,R16
     rol R16
     rcall delay
     ;
     rjmp main ; repaet until power removed :-)

; provides some delay so that the LED is visible
delay:
     ldi R29, $20
WGLOOP0:   ldi R30, $ff
WGLOOP1:   ldi R31, $ff
WGLOOP2:   dec R31
     brne WGLOOP2
     dec R30
     brne WGLOOP1
     dec R29
     brne WGLOOP0
     ret