at91sam9263 ATMEL Corporation, at91sam9263 Datasheet - Page 487

• Manufacturer Part Number: at91sam9263
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

32.5.4
Figure 32-8. Master Read with One Data Byte
Figure 32-9. Master Read with Multiple Data Bytes
32.5.5
487
TXCOMP
RXRDY
TWD
AT91SAM9263 Preliminary
Master Receiver Mode
Internal Address
S
Write START Bit
DADR
The read sequence begins by setting the START bit. After the start condition has been sent, the
master sends a 7-bit slave address to notify the slave device. The bit following the slave address
indicates the transfer direction, 1 in this case (MREAD = 1 in TWI_MMR). During the acknowl-
edge clock pulse (9th pulse), the master releases the data line (HIGH), enabling the slave to pull
it down in order to generate the acknowledge. The master polls the data line during this clock
pulse and sets the NACK bit in the status register if the slave does not acknowledge the byte.
If an acknowledge is received, the master is then ready to receive data from the slave. After data
has been received, the master sends an acknowledge condition to notify the slave that the data
has been received except for the last data, after the stop condition. See
RXRDY bit is set in the status register, a character has been received in the receive-holding reg-
ister (TWI_RHR). The RXRDY bit is reset when reading the TWI_RHR.
When a single data byte read is performed, with or without internal address (IADR), the START
and STOP bits must be set at the same time. See
performed, with or without internal address (IADR), the STOP bit must be set after the next-to-
last data received. See
The TWI interface can perform various transfer formats: Transfers with 7-bit slave address
devices and 10-bit slave address devices.
TXCOMP
RXRDY
R
TWD
A
S
DATA n
Write START &
STOP Bit
DADR
Figure
Read RHR
A
DATA n
32-9. For Internal Address usage see
DATA (n+1)
R
A
A
DATA (n+1)
Read RHR
DATA
DATA (n+m)-1
Figure
Read RHR
32-8. When a multiple data byte read is
N
DATA (n+m)-1
A
Read RHR
P
after next-to-last data read
DATA (n+m)
Section
Write STOP Bit
Figure
6249D–ATARM–20-Dec-07
32.5.5.
N
32-9. When the
DATA (n+m)
Read RHR
P