AT90S2313-8bit-UpDownCounter

This project shows the 8bit Timer application of AT90S2313. It is being designed to count from 00-FF at a speed of clk/8. Whenever an over flow occurs it displays odd numbers in the reverse order.

This project database uses one AT90S2313 Microcontroller, two 7-segment displays & 2 display drivers

The program is as shown:

__SREG__ = 0x3f

__SP_H__ = 0x3e

__SP_L__ = 0x3d

__tmp_reg__ = 0

__zero_reg__ = 1

.global __do_copy_data

.global __do_clear_bss

.text

.global main

.type main, @function

main:

ldi r21,0x00

ldi r16,0xff

ldi R19,0X02

out 0x32,r21 ; Initializing ‘TCNT0’ Register for Timer 0

out 0x39,r19 ; Setting the TOIE0 Bit of ‘TIMSK’ Register

out 0x17,R16 ; Setting up the ‘DDRB’ Register in Output Mode

sei

ldi r18,0x02

out 0x33,r18 ; Starting the 8-Bit Timer 0

LOOP1:

in r28, 0x32 ; Outputting the TCNT0 value through PORTB

out 0x18 ,R28

rjmp LOOP1

;----- TIMER 0 - INTERRUPT SERVICE ROUTINE----

;------- reverse counting decremented by 2----

; ---------------VECTOR6-------------------

.size main, .-main

.global __vector_6

.type __vector_6, @function

__vector_6:

ldi r18,0x00 ; Stopping the Timer

out 0x33,r18

clc

in r21, 0x18 ; Inputting the PORTB value on R21

LOOP2:

subi r21, 0x02 ; Decrementing R21 by 2

out 0x18, r21 ; Outputting the value through PORTB

brcc LOOP2 ; Checking for Carry Flag

rjmp main