SAM3X8E Atmel Corporation, SAM3X8E Datasheet - Page 719

• Manufacturer Part Number: SAM3X8E
• Manufacturer: Atmel Corporation

Figure 33-10. Master Read with Multiple Data Bytes
33.8.6
33.8.6.1
11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12
TXCOMP
RXRDY
TWD
Internal Address
S
7-bit Slave Addressing
Write START Bit
DADR
RXRDY is used as Receive Ready for the PDC receive channel.
The TWI interface can perform various transfer formats: Transfers with 7-bit slave address
devices and 10-bit slave address devices.
When Addressing 7-bit slave devices, the internal address bytes are used to perform random
address (read or write) accesses to reach one or more data bytes, within a memory page loca-
tion in a serial memory, for example. When performing read operations with an internal address,
the TWI performs a write operation to set the internal address into the slave device, and then
switch to Master Receiver mode. Note that the second start condition (after sending the IADR) is
sometimes called “repeated start” (Sr) in I2C fully-compatible devices. See
Figure 33-11
The three internal address bytes are configurable through the Master Mode register
(TWI_MMR).
If the slave device supports only a 7-bit address, i.e. no internal address, IADRSZ must be set to
0.
In the figures below the following abbreviations are used:
• S
• Sr
• P
• W
• R
• A
• N
• DADR
• IADR
R
A
and
Start
Repeated Start
Stop
Write
Read
Acknowledge
Not Acknowledge
Device Address
Internal Address
DATA n
Figure 33-13
Read RHR
A
DATA n
for Master Write operation with internal address.
DATA (n+1)
A
DATA (n+1)
Read RHR
DATA (n+m)-1
DATA (n+m)-1
A
Read RHR
after next-to-last data read
DATA (n+m)
Write STOP Bit
Figure
SAM3X/A
SAM3X/A
N
33-12. See
DATA (n+m)
Read RHR
P
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