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AHB-Lite3

Configuration and instantiation

First each time you want to create a AHB-Lite3 bus, you will need a configuration object. This configuration object is an AhbLite3Config and has following arguments :

Parameter name	Type	Default	Description
addressWidth	Int		Width of HADDR (byte granularity)
dataWidth	Int		Width of HWDATA and HRDATA

There is in short how the AHB-Lite3 bus is defined in the SpinalHDL library :

case class AhbLite3(config: AhbLite3Config) extends Bundle with IMasterSlave {
  //  Address and control
  val HADDR = UInt(config.addressWidth bits)
  val HSEL = Bool()
  val HREADY = Bool()
  val HWRITE = Bool()
  val HSIZE = Bits(3 bits)
  val HBURST = Bits(3 bits)
  val HPROT = Bits(4 bits)
  val HTRANS = Bits(2 bits)
  val HMASTLOCK = Bool()

  //  Data
  val HWDATA = Bits(config.dataWidth bits)
  val HRDATA = Bits(config.dataWidth bits)

  //  Transfer response
  val HREADYOUT = Bool()
  val HRESP = Bool()

  override def asMaster(): Unit = {
    out(HADDR,HWRITE,HSIZE,HBURST,HPROT,HTRANS,HMASTLOCK,HWDATA,HREADY,HSEL)
    in(HREADYOUT,HRESP,HRDATA)
  }
}

There is a short example of usage :

val ahbConfig = AhbLite3Config(
  addressWidth = 12,
  dataWidth    = 32
)
val ahbX = AhbLite3(ahbConfig)
val ahbY = AhbLite3(ahbConfig)

when(ahbY.HSEL) {
  // ...
}

Variations

There is an AhbLite3Master variation. The only difference is the absence of the HREADYOUT signal. This variation should only be used by masters while the interconnect and slaves use AhbLite3.