82870P2P64H2 Datasheet, PDF (90/217 Pages) –

Register Description
R
3.3.2.7
SIR—Serial Input Register
Offset:
10–11h
Default Value: 00h
Attribute:
Size:
R/W, RO
16 bits
This register allows for the scanning of additional serial input data on the hot plug serial input
stream. The purpose is to provide a mechanism for accessing additional general-purpose or user-
defined input data. Note that this is only possible when operating in Serial mode. To read a byte
from the scan chain, first write the appropriate number to the Serial Input Byte Pointer register,
wait for the Serial Input Busy Status to indicate that the shift is complete, then read the Serial Input
Data register. A write to the Serial Input Byte Pointer is ignored if the Serial Input Busy Status bit
already indicates that a shift is in progress. The value in the Data register is unpredictable while
the shift is in progress. Once the shift is complete, the Data register remains unchanged until the
Byte Pointer is written again.
The scan in process for the SID byte (pointed to by SIBP) will start whenever a write to any byte
of the DWord at memory offset 10h is detected.
Note: This register has no purpose when the hot plug controller is operating in 1-slot or 2-slot parallel
mode, because the input serial data stream is internal to P64H2.
Bits
Description
15
14:13
12
11:8
7:0
Serial Input Busy Status (SIBS).
1 = This bit is set to 1 when this register is written and remains 1 until the selected byte has
been shifted into the Serial Input Data register.
Reserved
Reserved for Future Expansion (RSVD). Reserved for future expansion of the serial input chain
length.
Serial Input Byte Pointer (SIBP). Read as written. Writing any value n causes the serial input
logic to load the external shift registers and shift (N+1)*8 times, so that byte N is shifted into the
Serial Input Data register.
Serial Input Data (SID). This register is updated from the external shift registers every time the
Serial Input Register is written. If the pointer points to an internal shift register (values 3–0), the
register value is a copy of the appropriate internal shift register input state.
3.3.2.8
GPO—General Purpose Output Register
Offset:
13h
Default Value: 00h
Attribute:
Size:
R/W
8 bits
This register contains the general-purpose outputs that are shifted out at the front of a serial out
sequence. Note that this register has no purpose when the hot plug controller is operating in 1-slot
or 2-slot parallel mode, because the output serial data stream is internal to P64H2.
Bits
Description
7:0
General Purpose Output (GPO). The bits in this register are reflected in the internal serial
output register, along with the other serial outputs bits.
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Intel^® 82870P2 P64H2 Datasheet