flow.rst

Flow

Specification

The Flow interface is a simple valid/payload protocol which means the slave can't halt the bus. It could be used to represent data coming from an UART controller, requests to write an on-chip memory, etc.

Signal	Type	Driver	Description	Don't care when
valid	Bool	Master	When high => payload present on the interface
payload	T	Master	Content of the transaction	valid is low

Functions

Syntax	Description	Return	Latency
Flow(type : Data)	Create a Flow of a given type	Flow[T]
master/slave Flow(type : Data)	Create a Flow of a given type Initialized with corresponding in/out setup	Flow[T]
x.m2sPipe()	Return a Flow drived by x through a register stage that cut valid/payload paths	Flow[T]	1
x.stage()	Equivalent to x.m2sPipe()	Flow[T]	1
x << y y >> x	Connect y to x		0
x <-< y y >-> x	Connect y to x through a m2sPipe		1
x.throwWhen(cond : Bool)	Return a Flow connected to x When cond is high, transaction are dropped	Flow[T]	0
x.toReg()	Return a register which is loaded with payload when valid is high	T
x.setIdle()	Set the Flow in an Idle state: valid is False and don't care about payload.
x.push(newPayload: T)	Assign a new valid payload to the Flow. valid is set to True.

Code example

/../examples/src/main/scala/spinaldoc/libraries/flow/FlowExample.scala

Simulation Support

Class	Usage
FlowMonitor	Used for both master and slave sides, calls function with payload if Flow transmits data.
FlowDriver	Testbench master side, drives values by calling function to apply value (if available). Function must return if value was available. Supports random delays.
ScoreboardInOrder	Often used to compare reference/dut data

/../examples/src/main/scala/spinaldoc/libraries/flow/SimSupport.scala