Atmel SAM9X25, Manual

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759
11054A–ATARM–27-Jul-11
SAM9X25
759
11054A–ATARM–27-Jul-11
SAM9X25
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:
Figure 38-11. Master Write with One, Two or Three Bytes Internal Address and One Data Byte
Figure 38-12. Master Read with One, Two or Three Bytes Internal Address and One Data Byte
38.8.6.2 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.)
• S
Start
• Sr
Repeated Start
• P
Stop
• W
Write
• R
Read
• A
Acknowledge
• N
Not Acknowledge
• DADR
Device Address
• IADR
Internal Address
S DADR W A IADR(23:16) A IADR(15:8) A IADR(7:0) A DATA A P
S DADR W A IADR(15:8) A IADR(7:0) A P DATA A
A IADR(7:0) A P
DATA A S DADR W
TWD
Three bytes internal address
Two bytes internal address
One byte internal address
TWD
TWD
S DADR
W
A IADR(23:16) A
IADR(15:8)
A
IADR(7:0) A
S DADR W A IADR(15:8) A IADR(7:0) A
A
IADR(7:0) A
S DADR W
DATA N P
Sr DADR R A
Sr DADR R A DATA N P
Sr DADR R A DATA N P
TWD
TWD
TWD
Three bytes internal address
Two bytes internal address
One byte internal address