Intel BFCBASE Data Sheet - Page 117

SMBus Device Addressing, Processor, Information, and Scratch, EEPROM, 1Kbit each, SM_VCC

Page 117 highlights

Features Figure 7-2. Logical Schematic of SMBus Circuitry SM_VCC SM_EP_A0 SM_EP_A1 SM_EP_A2 SM_WP VCC Processor Information ROM and Scratch EEPROM (1Kbit each) DATA CLK 7.4.1 SM_CLK SM_DAT VSS Note: Actual implementation may vary. This figure is provided to offer a general understanding of the architecture. All SMBus pull-up and pull-down resistors are 10 kΩ and located on the processor. SMBus Device Addressing Of the addresses broadcast across the SMBus, the memory component claims those of the form "1010XXXZb". The "XXX" bits are defined by pull-up and pull-down resistors on the system baseboard. These address pins are pulled down weakly (10 kΩ) on the processor substrate to ensure that the memory components are in a known state in systems which do not support the SMBus (or only support a partial implementation). The "Z" bit is the read/write bit for the serial bus transaction. Note that addresses of the form "0000XXXXb" are Reserved and should not be generated by an SMBus master. The system designer must also ensure that their particular implementation does not add excessive capacitance to the address inputs. Excess capacitance at the address inputs may cause address recognition problems. Refer to the appropriate platform design guide document. Figure 7-2 shows a logical diagram of the pin connections. Table 7-3 describe the address pin connections and how they affect the addressing of the devices. Document Number: 318080-002 117

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Document Number: 318080-002
117
Features
Note:
Actual implementation may vary. This figure is provided to offer a general understanding of the
architecture. All SMBus pull-up and pull-down resistors are 10 k
Ω
and located on the processor.
7.4.1
SMBus Device Addressing
Of the addresses broadcast across the SMBus, the memory component claims those of
the form “1010XXXZb”. The “XXX” bits are defined by pull-up and pull-down resistors
on the system baseboard. These address pins are pulled down weakly (10 k
Ω
) on the
processor substrate to ensure that the memory components are in a known state in
systems which do not support the SMBus (or only support a partial implementation).
The “Z” bit is the read/write bit for the serial bus transaction.
Note that addresses of the form “0000XXXXb” are Reserved and should not be
generated by an SMBus master. The system designer must also ensure that their
particular implementation does not add excessive capacitance to the address inputs.
Excess capacitance at the address inputs may cause address recognition problems.
Refer to the appropriate platform design guide document.
Figure 7-2
shows a logical diagram of the pin connections.
Table 7-3
describe the
address pin connections and how they affect the addressing of the devices.
Figure 7-2.
Logical Schematic of SMBus Circuitry
Processor
Information
ROM
and Scratch
EEPROM
(1Kbit each)
VSS
SM_VCC
SM_EP_A0
SM_EP_A1
SM_EP_A2
SM_WP
SM_CLK
SM_DAT
VCC
CLK
DATA