SAM7S256_14 Datasheet, PDF (302/775 Pages) ATMEL Corporation – ARM-based Flash MCU

29.6.5.2
10-bit Slave Addressing
For a slave address higher than 7 bits, the user must configure the address size (IADRSZ) and
set the other slave address bits in the internal address register (TWI_IADR). The two remaining
Internal address bytes, IADR[15:8] and IADR[23:16] can be used the same as in 7-bit Slave
Addressing.
Example: Address a 10-bit device (10-bit device address is b1 b2 b3 b4 b5 b6 b7 b8 b9 b10)
1. Program IADRSZ = 1,
2. Program DADR with 1 1 1 1 0 b1 b2 (b1 is the MSB of the 10-bit address, b2, etc.)
3. Program TWI_IADR with b3 b4 b5 b6 b7 b8 b9 b10 (b10 is the LSB of the 10-bit
address)
Figure 29-12 below shows a byte write to an Atmel AT24LC512 EEPROM. This demonstrates
the use of internal addresses to access the device.
Figure 29-12. Internal Address Usage
S
W
T
R
S
A
I
T
R ^Device
T
FIRST
SECOND
O
T Address
E WORD ADDRESS WORD ADDRESS
DATA
P
0
M
LR A M
A
LA
A
S
S/ C S
C
SC
C
B
BW K B
K
BK
K
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
302