ATmega16 datasheet(185/357 Pages) ATMEL

185 / 357 page

185

2466S–AVR–05/09

ATmega16(L)

Assembly code example

C example

Comments

ldi

r16, (1<<TWINT)|(1<<TWSTA)|

(1<<TWEN)

out

TWCR, r16

TWCR = (1<<TWINT)|(1<<TWSTA)|

(1<<TWEN)

Send START condition

wait1:

r16,TWCR

sbrs

r16,TWINT

rjmp

wait1

while

(!(TWCR & (1<<TWINT)))

;

Wait for TWINT Flag set. This indicates

that the START condition has been

transmitted

r16,TWSR

andi

r16, 0xF8

cpi

r16, START

brne

ERROR

((TWSR & 0xF8) != START)

ERROR();

Check value of TWI Status Register. Mask

prescaler bits. If status different from

START go to ERROR

ldi

r16, SLA_W

out

TWDR, r16

ldi

r16, (1<<TWINT) | (1<<TWEN)

out

TWCR, r16

TWDR = SLA_W;

TWCR = (1<<TWINT) | (1<<TWEN);

Load SLA_W into TWDR Register. Clear

TWINT bit in TWCR to start transmission

of address

wait2:

r16,TWCR

sbrs

r16,TWINT

rjmp

wait2

while

(!(TWCR & (1<<TWINT)))

;

Wait for TWINT Flag set. This indicates

that the SLA+W has been transmitted,

and ACK/NACK has been received.

r16,TWSR

andi

r16, 0xF8

cpi

r16, MT_SLA_ACK

brne

ERROR

((TWSR & 0xF8) != MT_SLA_ACK)

ERROR();

Check value of TWI Status Register. Mask

prescaler bits. If status different from

MT_SLA_ACK go to ERROR

ldi

r16, DATA

out

TWDR, r16

ldi

r16, (1<<TWINT) | (1<<TWEN)

out

TWCR, r16

TWDR = DATA;

TWCR = (1<<TWINT) | (1<<TWEN);

Load DATA into TWDR Register. Clear

TWINT bit in TWCR to start transmission

of data

wait3:

r16,TWCR

sbrs

r16,TWINT

rjmp

wait3

while

(!(TWCR & (1<<TWINT)))

;

Wait for TWINT Flag set. This indicates

that the DATA has been transmitted, and

ACK/NACK has been received.

r16,TWSR

andi

r16, 0xF8

cpi

r16, MT_DATA_ACK

brne

ERROR

((TWSR & 0xF8) != MT_DATA_ACK)

ERROR();

Check value of TWI Status Register. Mask

prescaler bits. If status different from

MT_DATA_ACK go to ERROR

ldi

r16, (1<<TWINT)|(1<<TWEN)|

(1<<TWSTO)

out

TWCR, r16

TWCR = (1<<TWINT)|(1<<TWEN)|

(1<<TWSTO);

Transmit STOP condition

ATmega16 датащи(PDF) 185 Page - ATMEL Corporation

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