无驱动检测(No driver on)

简介

SpinalHDL 将检查所有对设计有影响的组合信号是否被赋值。

示例

下面的代码：

class TopLevel extends Component {
  val result = out(UInt(8 bits))
  val a = UInt(8 bits)
  result := a
}

会报错：

NO DRIVER ON (toplevel/a :  UInt[8 bits]), defined at
  ***
  Source file location of the toplevel/a definition via the stack trace
  ***

一个可能的修复方法是：

class TopLevel extends Component {
  val result = out(UInt(8 bits))
  val a = UInt(8 bits)
  a := 42
  result := a
}