SBPH400-3 datasheet(18/43 Pages) STMICROELECTRONICS

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SBPH400-3

The Write Request is used to write to a register in the device. It is 17 bits long and is specified

in Table 2.9.

The Accelerate Control Request is used to control the use of arbitration acceleration in order

to prevent Cycle Start packet starvation. It is 6 bits long and is specified in Table 2.10

The Request Speed field in the bus request is encoded as specified in Table 2.11:

Table 2.9

Write register request format

Bit(s)

Name

Description

Start_Bit

Indicates the start of transfer. Always 1.

1-3

Request_Type

101b (Register write)

4-7

Address

Indicates the address of the physical register to be written.

8-15

Data

Indicates the data to be written to the specified physical register.

Stop_Bit

Indicates end of transfer. Always 0.

Table 2.10

Accelerate control request format

Bit(s)

Name

Description

Start_Bit

Indicates the start of transfer. Always 1.

1-3

Request_Type

110b (AccCtrl)

Acceleration_Select

0 = Decelerate

1 = Accelerate

Stop_Bit

Indicates end of transfer. Always 0.

Table 2.11

Request speed field

LR[4:6]

Data Rate

000

S100

001

not supported (S1600)

010

S200

011

not supported (S3200)

100

S400

101

reserved

110

not supported (S800)

111

reserved

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