Accessing signals of the simulation

Read and write signals

Each interface signal of the toplevel can be read and written from Scala:

Syntax	Description
`Bool.toBoolean`	Read a hardware `Bool` as a Scala `Boolean` value
`Bits`/`UInt`/`SInt.toInt`	Read a hardware `BitVector` as a Scala `Int` value
`Bits`/`UInt`/`SInt.toLong`	Read a hardware `BitVector` as a Scala `Long` value
`Bits`/`UInt`/`SInt.toBigInt`	Read a hardware `BitVector` as a Scala `BigInt` value
`SpinalEnumCraft.toEnum`	Read a hardware `SpinalEnumCraft` as a Scala `SpinalEnumElement` value
`Bool #= Boolean`	Assign a hardware `Bool` from an Scala `Boolean`
`Bits`/`UInt`/`SInt #= Int`	Assign a hardware `BitVector` from a Scala `Int`
`Bits`/`UInt`/`SInt #= Long`	Assign a hardware `BitVector` from a Scala `Long`
`Bits`/`UInt`/`SInt #= BigInt`	Assign a hardware `BitVector` from a Scala `BigInt`
`SpinalEnumCraft #= SpinalEnumElement`	Assign a hardware `SpinalEnumCraft` from a Scala `SpinalEnumElement`
`Data.randomize()`	Assign a random value to a SpinalHDL value.

dut.io.a #= 42
dut.io.a #= 42l
dut.io.a #= BigInt("101010", 2)
dut.io.a #= BigInt("0123456789ABCDEF", 16)
println(dut.io.b.toInt)

Accessing signals inside the component’s hierarchy

To access signals which are inside the component’s hierarchy, you have first to set the given signal as simPublic.

You can add this simPublic tag directly in the hardware description:

object SimAccessSubSignal {
  import spinal.core.sim._

  class TopLevel extends Component {
    val counter = Reg(UInt(8 bits)) init(0) simPublic() // Here we add the simPublic tag on the counter register to make it visible
    counter := counter + 1
  }

  def main(args: Array[String]) {
    SimConfig.compile(new TopLevel).doSim{dut =>
      dut.clockDomain.forkStimulus(10)

      for(i <- 0 to 3) {
        dut.clockDomain.waitSampling()
        println(dut.counter.toInt)
      }
    }
  }
}

Or you can add it later, after having instantiated your toplevel for the simulation:

object SimAccessSubSignal {
  import spinal.core.sim._
  class TopLevel extends Component {
    val counter = Reg(UInt(8 bits)) init(0)
    counter := counter + 1
  }

  def main(args: Array[String]) {
    SimConfig.compile {
      val dut = new TopLevel
      dut.counter.simPublic()
      dut
    }.doSim{dut =>
      dut.clockDomain.forkStimulus(10)

      for(i <- 0 to 3) {
        dut.clockDomain.waitSampling()
        println(dut.counter.toInt)
      }
    }
  }
}