atmega323l ATMEL Corporation, atmega323l Datasheet - Page 121

• Manufacturer Part Number: atmega323l
• Description: Atmega323 8-bit Avr Microcontroller With 32k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

Assembly Code Example –
Slave Transmitter Mode
1457G–AVR–09/03
Figure 58. Formats and States in the Slave Transmitter Mode
Reception of the
Own Slave Address
and One or
More Data Bytes
Arbitration Lost as Master
and Addressed as Slave
Last Data Byte Transmitted.
Switched to not Addressed
Slave (TWEA = '0')
; Part specific include file and TWI include file must be included.
; <Initialize registers, including TWAR, TWBR and TWCR>
; <Receive START condition and SLA+R>
wait14:in
wait15:in
; <Send more data bytes if needed>
From Master to Slave
From Slave to Master
ldi
out
sbrs r16, TWINT
rjmp wait14
in
cpi
brne ERROR
ldi
out
ldi
out
sbrs r16, TWINT
rjmp wait15
in
cpi
brne ERROR
S
r16, (1<<TWINT) | (1<<TWEA) | (1<<TWEN)
TWCR, r16
r16,TWCR
r16, TWSR
r16, ST_SLA_ACK
r16, 0x33
TWDR, r16
r16, (1<<TWINT) | (1<<TWEA) | (1<<TWEN)
TWCR, r16
r16,TWCR
r16, TWSR
r16, ST_DATA_ACK
SLA
R
DATA
$A8
$B0
A
A
; Enable TWI in Slave Transmitter mode
; Wait for TWINT Flag set. This indicates that
; SLA+R has been received, and ACK/NACK has
; been returned
; Check value of TWI Status Register. If status
; different from ST_SLA_ACK, go to ERROR
; Load data(here, data=0x33)into TWDR Register
; Clear TWINT bit in TWCR to start transmission
; of data. Setting TWEA indicates that ACK
; should be received when transfer finished
; Wait for TWINT Flag set. This indicates that
; data has been transmitted, and ACK/NACK has
; been received
; Check value of TWI Status Register. If status
; different from ST_DATA_ACK, go to ERROR
n
A
DATA
Any Number of Data Bytes
and their Associated Acknowledge Bits
This Number (Contained in TWSR) Corresponds
to a Defined State of the Two-wire Serial Bus
$B8
A
ATmega323(L)
DATA
$C0
$C8
A
A
P or S
All 1's
P or S
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