PRELIMINARY TECHNICAL DATA
ADM1026
– 1 1 –
REV. PrL
PRELIMINAR
Y
TECHNICAL
DA
TA
byte of the EEPROM address and the second data byte
is the actual data. Bit 1 of EEPROM Register 3 must
be set. This is illustrated in Figure 3e.
S
S LAV E
ADDRE S S
W
A
E E P RO M
ADDRE S S
HIGH BY TE
(80h TO 9Fh)
E E P RO M
ADDRE S S
LOW BY TE
(00h TO FFh)
A
A DAT A A P
1
2
3
4
5
6
7
8
9 10
Figure 3d. Single Byte Write To EEPROM
Block Write
In this operation the master device writes a block of data
to a slave device. The start address for a block write must
previously have been set. In the case of the ADM1026 this
is done by a Send Byte operation to set a RAM address or
a Write Byte/Word operation to set an EEPROM address.
1. The master device asserts a start condition on SDA.
2. The master sends the 7-bit slave address followed by
the write bit (low).
3. The addressed slave device asserts ACK on SDA.
4. The master sends a command code that tells the slave
device to expect a block write. The ADM1026 com-
mand code for a block read is A0h (10100000).
5. The slave asserts ACK on SDA.
6. The master sends a data byte that tells the slave device
how many data bytes will be sent. The SMBus specifi-
cation allows a maximum of 32 data bytes to be sent in
a block write.
7. The slave asserts ACK on SDA.
8. The master sends N data bytes.
9. The slave asserts ACK on SDA after each data byte.
10.The master asserts a STOP condition on SDA to end
the transaction.
S
S LAV E
ADDRE S S
W A
CO M M AND A0h
(BLOCK W RITE )
BY TE
CO UN T
A
A
DATA 1
A
P
A
DATA 2
DATA N A
1
2
3
4
5
6
7
8
9
10
Figure 3e. Block Write To EEPROM Or RAM
When performing a block write to EEPROM, bit 1 of
EEPROM Register 3 must be set.
Unlike some EEPROM devices which limit block writes to
within a page boundary, there is no limitation on the start ad-
dress when performing a block write to EEPROM, except:
1. There must be at least N locations from the start ad-
dress to the highest EEPROM address (9FFF), to avoid-
ing writing to invalid addresses.
2. If the addresses cross a page boundary, both pages must
be erased before programming.
ADM1026 READ OPERATIONS
The ADM1026 uses the following SMBus read protocols.
RECEIVE BYTE
In this operation the master device receives a single byte
from a slave device, as follows:
1.The master device asserts a start condition on SDA.
2.The master sends the 7-bit slave address followed by the
read bit (high).
3.The addressed slave device asserts ACK on SDA.
4.The master receives a data byte.
5.The master asserts NO ACK on SDA.
6.The master asserts a STOP condition on SDA and the
transaction ends.
In the ADM1026, the receive byte protocol is used to read
a single byte of data from A RAM or EEPROM location
whose address has previously been set by a send byte or
write byte/word operation. This is illustrated in Figure 3f.
When reading from EEPROM, Bit 0 of EEPROM
register 3 must be set.
S
S LAV E
ADDRES S
R
A
DAT A
)
P
1
2
3
4
5
6
Figure 3f. Single Byte Read From EEPROM Or RAM
Block Read
In this operation the master device reads a block of data
from a slave device. The start address for a block read
must previously have been set. In the case of the ADM
1026 this is done by a Send Byte operation to set a RAM
address or a Write Byte/Word operation to set an
EEPROM address. The block read operation itself
consists of a Send Byte operation that sends a block rtead
command to the slave, immediately followed by a repeat
start and a read operation that reads out multiple data
bytes, as follows:
1.The master device asserts a start condition on SDA.
2.The master sends the 7-bit slave address followed by the
write bit (low).
3.The addressed slave device asserts ACK on SDA.
4.The master sends a command code that tells the slave
device to expect a block read. The ADM1026 command
code for a block read is A1h (10100001).
5.The slave asserts ACK on SDA.
6.The master asserts a repeat start condition on SDA.
7.The master sends the 7-bit slave address followed by the
read bit (high).
8.The slave asserts ACK on SDA.
9.The master receives a byte count data byte that tells it
how many data bytes will be received. The SMBus
specification allows a maximum of 32 data bytes to be
received in a block read.
10. The master asserts ACK on SDA.
11. The master receives N data bytes.
12. The master asserts ACK on SDA after each data byte.
13. The slave does not acknowledge after the Nth data
byte.
14. The master asserts a STOP condition on SDA to end
the transaction.
