adm1069ast-reel Analog Devices, Inc., adm1069ast-reel Datasheet - Page 30

• Manufacturer Part Number: adm1069ast-reel
• Description: Super Sequencer With Margining Control
• Manufacturer: Analog Devices, Inc.

ADM1069
SMBus PROTOCOLS FOR RAM AND EEPROM
The ADM1069 contains volatile registers (RAM) and nonvola-
tile registers (EEPROM). User RAM occupies addresses 0x00 to
0xDF; EEPROM occupies addresses 0xF800 to 0xFBFF.
Data can be written to and read from both RAM and EEPROM
as single data bytes. Data can be written only to unprogrammed
EEPROM locations. To write new data to a programmed loca-
tion, it must first be erased. EEPROM erasure cannot be done at
the byte level. The EEPROM is arranged as 32 pages of 32 bytes
each, and an entire page must be erased.
Page erasure is enabled by setting Bit 2 in the UPDCFG register
(Address 0x90) to 1. If this bit is not set, page erasure cannot
occur, even if the command byte (0xFE) is programmed across
the SMBus.
WRITE OPERATIONS
The SMBus specification defines several protocols for different
types of read and write operations. The following abbreviations
are used in Figure 39 to Figure 46:
•
•
•
•
•
•
The ADM1069 uses the following SMBus write protocols.
Send Byte
In a send byte operation, the master device sends a single
command byte to a slave device, as follows:
1.
2.
3.
4.
5.
6.
In the ADM1069, the send byte protocol is used for two
purposes:
•
S
P
R
W Write
A
A
The master device asserts a start condition on SDA.
The master sends the 7-bit slave address followed by the
write bit (low).
The addressed slave device asserts ACK on SDA.
The master sends a command code.
The slave asserts ACK on SDA.
The master asserts a stop condition on SDA and the
transaction ends.
To write a register address to RAM for a subsequent single
byte read from the same address, or a block read or write
starting at that address, as shown in Figure 38.
Start
Stop
Read
Acknowledge
No acknowledge
Rev. A | Page 30 of 36
•
Write Byte/Word
In a write byte/word operation, the master device sends a
command byte and one or two data bytes to the slave device, as
follows:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10. The master asserts a stop condition on SDA to end the
To erase a page of EEPROM memory. EEPROM memory
can be written to only if it is unprogrammed. Before
writing to one or more EEPROM memory locations that
are already programmed, the page or pages containing
those locations must first be erased. EEPROM memory is
erased by writing a command byte.
The master sends a command code that tells the slave
device to erase the page. The ADM1069 command code for
a page erasure is 0xFE (1111 1110). Note that, for a page
erasure to take place, the page address has to be given in
the previous write word transaction (see the Write
Byte/Word section). In addition, Bit 2 in the UPDCFG
register (Address 0x90) must be set to 1.
As soon as the ADM1069 receives the command byte, page
erasure begins. The master device can send a stop
command as soon as it sends the command byte. Page
erasure takes approximately 20 ms. If the ADM1069 is
accessed before erasure is complete, it responds with a no
acknowledge (NACK).
The master device asserts a start condition on SDA.
The master sends the 7-bit slave address followed by the
write bit (low).
The addressed slave device asserts ACK on SDA.
The master sends a command code.
The slave asserts ACK on SDA.
The master sends a data byte.
The slave asserts ACK on SDA.
The master sends a data byte (or asserts a stop condition at
this point).
The slave asserts ACK on SDA.
transaction.
Figure 38. Setting a RAM Address for Subsequent Read
S
S
1
1
ADDRESS
ADDRESS
SLAVE
SLAVE
2
2
Figure 39. EEPROM Page Erasure
W
W
A
A
3
3
(0x00 TO 0xDF)
COMMAND
ADDRESS
(0xFE)
BYTE
RAM
4
4
A
A
5
5
6
P
6
P