Xilinx UG181 manual 8Typical Flow Control Implementation for 4-Channel System

Models: UG181

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Chapter 4: Designing with the Core

Status for 16 channels each clock cycle can be written. The SnkStatAddr bus is used to select which 16 channels are written, and the core supports configurations of 1–256 channels. The 16 channels of FIFO Status that are written are addressed as follows:

Bank 0: SnkStatAddr[3:0]=0 for channels 15 to 0

Bank 1: SnkStatAddr[3:0]=1 for channels 31 to 16

Bank 2: SnkStatAddr[3:0]=2 for channels 47 to 32

Bank 3: SnkStatAddr[3:0]=3 for channels 63 to 48

...

Bank 14: SnkStatAddr[3:0]=14 for channels 239 to 224

Bank 15: SnkStatAddr[3:0]=15 for channels 255 to 240

The status that is written is mapped to the 16-bit bus as follows:

For Bank 0: SnkStatAddr[3:0]=0

SnkStat[1:0] => Channel 0, where SnkStat[1] is the MSB of the 2-bit status

SnkStat[3:2] => Channel 1

SnkStat[5:4] => Channel 2

...

SnkStat[11:10] => Channel 13

SnkStat[13:12] => Channel 14

SnkStat[15:14] => Channel 15

SPI-4.2 Sink Core

FIFO

Status I/F

User

Interface

MUX

Flow Control

Status:

Starving

Hungry

Satisfied

FIFO

Channel 0

FIFO

Channel 1

FIFO

Channel 2

FIFO

Channel 3

Programmable

Full

Figure 4-8:Typical Flow Control Implementation for 4-Channel System

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UG181 June 27, 2008

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Xilinx UG181 manual 8Typical Flow Control Implementation for 4-Channel System