IDT 89HPES24N3A, Руководство пользователя

Страница: 69 / 168

IDT SMBus Interfaces
PES24N3A User Manual 6 - 3 April 10, 2008
Notes
During serial EEPROM initialization, the master SMBus interface begins reading bytes starting at serial
EEPROM address zero. These bytes are interpreted as configuration blocks and sequential reading of the
serial EEPROM continues until the end of a configuration done block is reached or the serial EEPROM
address rolls over from 0xFFFF to 0x0. All register initialization performed by the serial EEPROM is
performed in double word quantities.
There are three configuration block types that may be stored in the serial EEPROM. The first type is a
single double word initialization sequence. A double word initialization sequence occupies six bytes in the
serial EEPROM and is used to initialize a single double word quantity in the PES24N3A. A double word
initialization sequence occupies six byes in the serial EEPROM and is used to initialize a single double
word quantity in the PES24N3A.
A single double word initialization sequence consists of three fields and its format is shown in Figure 6.2.
The CSR_SYSADDR field contains the double word CSR system address of the double word to be initial-
ized. The actual CSR system address, which is a byte address, equals this value with two lower zero bits
appended. The next field is the TYPE field that indicates the type of the configuration block. For single
double word initialization sequence, this value is always 0x0. The final DATA field contains the double word
initialization value.
Figure 6.2 Single Double Word Initialization Sequence Format
The second type of configuration block is the sequential double word initialization sequence. It is similar
to a single double word initialization sequence except that it contains a double word count that allows
multiple sequential double words to be initialized in one configuration block.
A sequential double word initialization sequence consists of four required fields and one to 65535
double word initialization data fields. The format of a sequential double word initialization sequence is
shown in Figure 6.3. The CSR_SYSADDR field contains the starting double word CSR system address to
be initialized. The next field is the TYPE field that indicates the type of the configuration block. For sequen-
tial double word initialization sequences, this value is always 0x1. The NUMDW field specifies the number
of double words initialized by the configuration block. This is followed by the number of DATA fields speci-
fied in the NUMDW field.
Serial EEPROM Size
24C32 4 KB
24C64 8 KB
24C128 16 KB
24C256 32 KB
24C512 64 KB
Table 6.2 PES24N3A Compatible Serial EEPROMs
Bit
0
Bit
1
Bit
2
Bit
3
Bit
4
Bit
5
Bit
6
Bit
7
Byte 0 CSR_SYSADDR[7:0]
CSR_SYSADDR[13:8]
TYPE
0x0
Byte 1
Byte 2 DATA[7:0]
Byte 3 DATA[15:8]
Byte 4 DATA[23:16]
Byte 5 DATA[31:24]