Chisel Book的第一版带有中文，但是内容并没有后面V4完善，作为第一本入门书。

前面已经写了很多关于Chisel的内容，本文紧跟 【Chisel】03 开始。

Debug

  1. 运行sbt的路径出现问题，需要在项目的根目录下运行。
    • 否则会出现找不到chisel的报错。
  2. 中间使用了switch但是忘记引用包：import chisel3 . util ._
    • 出现找不到switch的报错。
  3. 最后一个重要的bug，还是关于switch使用。

switch报错

源代码

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package seg                                            

import chisel3._
import chisel3.util._
import chisel3.experimental._
/**
 * Digital display exampale.Transform decimal number to
 * segment display module's control code
 */

class SegDisplay extends Module {
  val io = IO(new Bundle{
    val input = Input(UInt(4.W))
    val output = Output(UInt(8.W))
  })
  switch (io.input) {
    is (0.U) { io.output := "h7E".U(8.W) }
    is (1.U) { io.output := "h30".U(8.W) }
    is (2.U) { io.output := "h6D".U(8.W) }
    is (3.U) { io.output := "h79".U(8.W) }
    is (4.U) { io.output := "h33".U(8.W) }
    is (5.U) { io.output := "h5B".U(8.W) }
    is (6.U) { io.output := "h5F".U(8.W) }
    is (7.U) { io.output := "h70".U(8.W) }
    is (8.U) { io.output := "h7F".U(8.W) }
    is (9.U) { io.output := "h7B".U(8.W) }
    is (10.U) { io.output := "h77".U(8.W) }
    is (11.U) { io.output := "h1F".U(8.W) }
    is (12.U) { io.output := "h4E".U(8.W) }
    is (13.U) { io.output := "h3D".U(8.W) }
    is (14.U) { io.output := "h4F".U(8.W) }
    is (15.U) { io.output := "h47".U(8.W) }
  }
}

出现报错：

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[error] (run-main-0) firrtl.passes.CheckInitialization$RefNotInitializedExc
eption:  : [module SegDisplay]  Reference io is not fully initialized.

出错原因，switch赋值的时候需要给输出默认值，不能有不定状态。

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package seg                                            

import chisel3._
import chisel3.util._
import chisel3.experimental._
/**
 * Digital display exampale.Transform decimal number to
 * segment display module's control code
 */

class SegDisplay extends Module {
  val io = IO(new Bundle{
    val input = Input(UInt(4.W))
    val output = Output(UInt(8.W))
  })
  // +++ newly added
  io.output := 0.U(8.W)
  // +++ 
  switch (io.input) {
    is (0.U) { io.output := "h7E".U(8.W) }
    is (1.U) { io.output := "h30".U(8.W) }
    is (2.U) { io.output := "h6D".U(8.W) }
    is (3.U) { io.output := "h79".U(8.W) }
    is (4.U) { io.output := "h33".U(8.W) }
    is (5.U) { io.output := "h5B".U(8.W) }
    is (6.U) { io.output := "h5F".U(8.W) }
    is (7.U) { io.output := "h70".U(8.W) }
    is (8.U) { io.output := "h7F".U(8.W) }
    is (9.U) { io.output := "h7B".U(8.W) }
    is (10.U) { io.output := "h77".U(8.W) }
    is (11.U) { io.output := "h1F".U(8.W) }
    is (12.U) { io.output := "h4E".U(8.W) }
    is (13.U) { io.output := "h3D".U(8.W) }
    is (14.U) { io.output := "h4F".U(8.W) }
    is (15.U) { io.output := "h47".U(8.W) }
  }
}