AT32UC3L064_1 ATMEL [ATMEL Corporation], AT32UC3L064_1 Datasheet - Page 490

• Manufacturer Part Number: AT32UC3L064_1
• Description: AVR32 32-bit Microcontroller
• Manufacturer: ATMEL [ATMEL Corporation]

Figure 22-7. Master Write with Multiple Data Bytes
22.8.4
32099A–AVR32–06/09
TCOMP
TXRDY
TWD
Master Receiver Mode
Write THR (Data n)
NBYTES set to m
S
DADR
Figure 22-6. Master Write with One Data Byte
A START condition is transmitted and master receiver mode is initiated when the bus is free
and CMDR has been written with START=1 and READ=1. START and SADR+R will then be
transmitted. During the address acknowledge clock pulse (9th pulse), the master releases the
data line (HIGH), enabling the slave to pull it down in order to acknowledge the address. The
master polls the data line during this clock pulse and sets the Address Not Acknowledged bit
(ANAK) in the Status Register if no slave acknowledges the address.
After the address phase, the following is repeated:
while (NBYTES>0)
Programming CMDR with START=STOP=1 and NBYTES=0 will generate a transmission with
no data bytes, ie START, DADR+R, STOP
The TWI transfers require the master to acknowledge each received data byte. During the
acknowledge clock pulse (9th pulse), the slave releases the data line (HIGH), enabling the
master to pull it down in order to generate the acknowledge. All data bytes except the last are
1. Wait until RHR is empty, stretching low period of TWCK. SR.RXRDY indicates the
2. Release TWCK generating a clock that the slave uses to transmit a data byte.
3. Place the received data byte in RHR, set RXRDY.
4. If NBYTES=0, generate a NAK after the data byte, otherwise generate an ACK.
5. Decrement NBYTES
6. If (NBYTES==0) and STOP=1, transmit STOP condition.
W
state of RHR. Software or a DMA controller must read any data byte present in RHR.
TCOMP
TXRDY
TWD
A
Write THR (DATA)
NBYTES set to 1
S
Write THR (Data n+1)
DATA n
DADR
A
W
A
Write THR (Data n+m)
DATA n+5
Last data sent
DATA
A
(ACK received and NBYTES= 0)
A
DATA n+m
STOP sent automatically
(ACK received and NBYTES= 0)
STOP sent automatically
P
AT32UC3L
A
P
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