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Apb3

Introduction

The AMBA3-APB bus is commonly used to interface low bandwidth peripherals.

Configuration and instanciation

First each time you want to create a APB3 bus, you will need a configuration object. This configuration object is an Apb3Config and has following arguments :

Parameter name	Type	Default	Description
addressWidth	Int		Width of PADDR (byte granularity)
dataWidth	Int		Width of PWDATA and PRDATA
selWidth	Int	1	With of PSEL
useSlaveError	Boolean	false	Specify the presence of PSLVERROR

There is in short how the APB3 bus is defined in the SpinalHDL library :

case class Apb3(config: Apb3Config) extends Bundle with IMasterSlave {
  val PADDR      = UInt(config.addressWidth bits)
  val PSEL       = Bits(config.selWidth bits)
  val PENABLE    = Bool()
  val PREADY     = Bool()
  val PWRITE     = Bool()
  val PWDATA     = Bits(config.dataWidth bits)
  val PRDATA     = Bits(config.dataWidth bits)
  val PSLVERROR  = if(config.useSlaveError) Bool() else null
  //...
}

There is a short example of usage :

val apbConfig = Apb3Config(
  addressWidth = 12,
  dataWidth    = 32
)
val apbX = Apb3(apbConfig)
val apbY = Apb3(apbConfig)

when(apbY.PENABLE){
  //...
}

Functions and operators

Name	Return	Description
X >> Y		Connect X to Y. Address of Y could be smaller than the one of X
X << Y		Do the reverse of the >> operator