You're reading an old version of this documentation.
For the latest stable release version, please have a look at master.

Dismiss

RGB to gray

Let’s imagine a component that converts an RGB color into a gray one, and then writes it into external memory.

io name	Direction	Description
clear	in	Clear all internal registers
r,g,b	in	Color inputs
wr	out	Memory write
address	out	Memory address, incrementing each cycle
data	out	Memory data, gray level

class RgbToGray extends Component{
  val io = new Bundle{
    val clear = in Bool
    val r,g,b = in UInt(8 bits)

    val wr = out Bool
    val address = out UInt(16 bits)
    val data = out UInt(8 bits)
  }

  def coef(value : UInt,by : Float) : UInt = (value * U((255*by).toInt,8 bits) >> 8)
  val gray = RegNext(
    coef(io.r,0.3f) +
    coef(io.g,0.4f) +
    coef(io.b,0.3f)
  )

  val address = CounterFreeRun(stateCount = 1 << 16)
  io.address := address
  io.wr := True
  io.data := gray

  when(io.clear){
    gray := 0
    address.clear()
    io.wr := False
  }
}