IDT 89HPES16NT2, User Manual

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IDT SMBus Interfaces
PES16NT2 User Manual 6 - 11 April 15, 2008
Notes
The format of the CMD field is shown in Figure 6.6 and described in Table 6.10.
Figure 6.6 CSR Register Read or Write CMD Field Format
Byte
Position
Field
Name Description
0 CCODE Command Code. Slave Command Code field described in Table 6.8.
1 BYTCNT Byte Count. The byte count field is only transmitted for block type
SMBus transactions. SMBus word and byte accesses do not contain
this field. The byte count field indicates the number of bytes following
the byte count field when performing a write or setting up for a read.
The byte count field is also used when returning data to indicate the
number of following bytes (including status).
Note that the byte count
field does not include the PEC byte if PEC is enabled.
2 CMD Command. This field encodes fields related to the CSR register read
or write operation.
3 ADDRL Address Low. Lower 8-bits of the doubleword CSR system address
of register to access.
4 ADDRU Address Upper. Upper 6-bits of the doubleword CSR system
address of register to access. Bits 6 and 7 in the byte must be zero
and are ignored by the hardware.
5 DATALL Data Low Low. Bits [7:0] of data doubleword.
6 DATALM Data Low Middle. Bits [15:8] of data doubleword.
7 DATAUM Data Upper Middle. Bits [23:16] of data doubleword.
8 DATAUU Data Upper Upper. Bits [31:24] of data doubleword.
Table 6.9 CSR Register Read or Write Operation Byte Sequence
Bit
Field
Name Type Description
0 BELL Read/Write Byte Enable Lower Lower . When set, the byte enable for bits [7:0] of
the data word is enabled.
1 BELM Read/Write Byte Enable Lower Middle . When set, the byte enable for bits [15:8]
of the data word is enabled.
2 BEUM Read/Write Byte Enable Upper Middle . When set, the byte enable for bits
[23:16] of the data word is enabled.
3 BEUU Read/Write Byte Enable Upper Upper . When set, the byte enable for bits [31:24]
of the data word is enabled.
Table 6.10 CSR Register Read or Write CMD Field Description (Part 1 of 2)
Bit
6
Bit
7
Bit
0
Bit
1
Bit
2
Bit
3
Bit
4
Bit
5
BELL BELM WERR BEUM BEUU OP RERR 0