.include "m8def.inc"

.def temp         = r16

.equ clock = 8000000
.equ twi_bit_rate = 32
.equ SCL_FREQ = clock/(16 + (2*twi_bit_rate*(4^0)))

rjmp Init

.org 0x011
rjmp twi_interrupt

Init:

ldi temp,low(ramend)
out spl,temp

ldi temp,high(ramend)
out sph,temp

ser temp
out ddrb,temp
out ddrc,temp
out portb,temp

ldi temp,(1<<twint)|(1<<twea)|(1<<twen)|(1<<twie)
out twcr, temp

ldi temp,twi_bit_rate
out TWBR,temp

ldi temp,(0<<twps0)|(0<<twps1)
out twsr,temp

ldi temp, $d0
out twar, temp

ldi temp,(1<<twsta)
out twcr,temp

sei 
  
 
main:

rjmp main  
  
  
twi_interrupt:  
in temp,twsr  
andi temp,$f8  
 
cpi temp,$08  
breq gestartet  
 
cpi temp,$18  
breq sl_hat_geantwortet  
  
cpi temp,$20  
breq keine_antwort

cpi temp,$28
breq sl_hat_geantwortet

cpi temp,$30  
breq keine_antwort

 
 
gestartet: 
ldi temp, $22  
out twdr,temp  
in   temp,twcr   
andi temp,(1<<twint)|(1<<twen) 
out  twcr,temp  
clr temp
out portb,temp
reti  
 
sl_hat_geantwortet: 
ld temp,z+
out twdr,temp

in   temp,twcr   
andi temp,(1<<twint)
out  twcr,temp
clr temp
out portb,temp
reti 

keine_antwort:
in   temp,twcr   
andi temp,(1<<twint)|(1<<twsta)|(1<<twsto)
out  twcr,temp
clr temp
out portb,temp
reti