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I have got a little problem of understanding how is suppose to work. Basically all what I need is to light up a led on each side of 7 segment display. They overlapping each other or only showing on left or right side. If someone can put me on right track will be nice. Thank you.

Something like this 

  ;Port Addresses 
.equ     DDRA   =$1A               ;Port A Data Direction Register Address 
.equ     PORTA   =$1B               ;Port A Output Address 

.equ     PINB  =$16               ;Port B Input Address 
.equ     DDRB   =$17               ;Port B Data Direction Register Address 

.equ     PINC  =$13               ;Port C Input Address 
.equ     DDRC   =$14               ;Port C Data Direction Register Address 

.equ  PORTD =$12    ;Port D Output Address
.equ  DDRD =$11    ;Port D Dara Direction Register Address

 ;Register Definitions 
.def     temp   =r16                ;Temporary storage register

 ;Program Initialisation 
 ;Initialise Input Ports  
         ldi    temp,$00 
         out    DDRB,temp         
   out DDRC, temp   

 ;Initialise output ports 
         ldi    temp,$FF 
         out    DDRA,temp         
         out    DDRD,temp         


loop:  ldi r17,$7f  ; left side
   out PORTA,r17
   ldi r18, $ff     ; right side
   out PORTA,r18
   rjmp loop
Peter Cordes
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Anton Pankov
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    We don't know how your leds are wired to the pins. – Jester Feb 27 '15 at 15:11
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    The meaning of, *They overlapping each other or only showing on left or right side.* is very unclear. Generally each 7-segment digit has each segment assigned to a bit somewhere in a port, and possibly another bit for a point (dot), if it exists. You need to know what those assignments are, then the problem becomes easy. And nobody here can help much further without those sorts of details. – lurker Feb 27 '15 at 17:04

2 Answers2

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There are two types of 7 segment LED displays. The difference is whether the segments turn on when a 1 is applied to the input, or a zero. You have to determine which kind you have, and how the pins of PORTA are connected to the leads of the display.

Other than that, the principle of operation is the same. There are seven segments of the number 8 and a dot. These are controlled by the bits of the number you are sending out PORTA.

$7f is either turning on one segment, or all but one. $ff is turning off all the segments or turning them all on.

You have to determine which segments you want to turn on, and which bits of PORTA controls those segments. You will find that numbers other than $7f and $ff are the numbers you need.

Do you want to be able to see the segments alternating? If so, you will need to include some sort of delay loop. The code right now changes the display too fast for the eye to see.

UncleO
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Port Addresses 
.equ     DDRA   =$1A               ;Port A Data Direction Register Address 
.equ     PORTA   =$1B               ;Port A Output Address 

.equ     PINB  =$16               ;Port B Input Address 
.equ     DDRB   =$17               ;Port B Data Direction Register Address 

.equ     PINC  =$13               ;Port C Input Address 
.equ     DDRC   =$14               ;Port C Data Direction Register Address 

.equ  PORTD =$12    ;Port D Output Address
.equ  DDRD =$11    ;Port D Dara Direction Register Address

 ;Register Definitions 
.def     temp   =r16                ;Temporary storage register
Peter Cordes
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Jack
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  • This looks like a copy/paste of the first part of the code block from the question. This doesn't look like an answer to the question, especially without any text to explain why this would be an answer. – Peter Cordes Apr 17 '22 at 13:04