哪位高手指导一下，为什么synplify综合成锁存器

zpsky

我觉得用尽了手段，没办法做成组合逻辑，不管怎么样，synplify都顽固的坚持是锁存器哪位高手指导一下，为什么synplify综合成锁存器
以下是代码：
always @ ( * )
begin
  flash_read_data=1'b0;
  fifo_write_data=1'b0;
  read_status=1'b0;
  flash_chip_erase=1'b0;
  flash_block_erase=1'b0;
  flash_sector_erase=1'b0;
  write_addr=1'b0;
  case({s_stb_i&s_cyc_i,s_addr_i[2:0],s_we_i})//synthesis full_case parallel_case
   5'b1_000_0: flash_read_data=1'b1;
   5'b1_000_1: fifo_write_data=1'b1;//Ö»ÊÇдÈ뻺³åÇø
   5'b1_001_0: read_status=1'b1;
   5'b1_010_1: write_addr=1'b1;//²Ù×÷µØÖ·ÔÝ´æ
   5'b1_011_1: flash_chip_erase=1'b1;
   5'b1_100_1: flash_block_erase=1'b1;
   5'b1_101_1: flash_sector_erase=1'b1;
   default:
    begin
     flash_read_data=1'b0;
     fifo_write_data=1'b0;
     read_status=1'b0;
     flash_chip_erase=1'b0;
     flash_block_erase=1'b0;
     flash_sector_erase=1'b0;
     write_addr=1'b0;
    end
      
  endcase
end


综合结果：

@W: CL118 :"D:\ledtx\txsource\txsource\spiif.v":233:2:233:5|Latch generated from always block for signal write_addr, probably caused by a missing assignment in an if or case stmt
@W: CL118 :"D:\ledtx\txsource\txsource\spiif.v":233:2:233:5|Latch generated from always block for signal read_status, probably caused by a missing assignment in an if or case stmt
@W: CL118 :"D:\ledtx\txsource\txsource\spiif.v":233:2:233:5|Latch generated from always block for signal flash_read_data, probably caused by a missing assignment in an if or case stmt
@W: CL118 :"D:\ledtx\txsource\txsource\spiif.v":233:2:233:5|Latch generated from always block for signal flash_chip_erase, probably caused by a missing assignment in an if or case stmt
@W: CL118 :"D:\ledtx\txsource\txsource\spiif.v":233:2:233:5|Latch generated from always block for signal flash_block_erase, probably caused by a missing assignment in an if or case stmt
@W: CL118 :"D:\ledtx\txsource\txsource\spiif.v":233:2:233:5|Latch generated from always block for signal fifo_write_data, probably caused by a missing assignment in an if or case stmt
@W: CL118 :"D:\ledtx\txsource\txsource\spiif.v":233:2:233:5|Latch generated from always block for signal flash_sector_erase, probably caused by a missing assignment in an if or case stmt

zpsky

//后面是中文注释，synplify没正确显示，

crazy4u

你这个代码写的太奇怪了
用几个assign语句就可以了

highball

每个需要改值的信号，在case每个条件后都被赋值一下，看看这样好使吗

zpsky

我把代码重新贴一下：

always @ ( * )
begin
  flash_read_data=1'b0;
  fifo_write_data=1'b0;
  read_status=1'b0;
  flash_chip_erase=1'b0;
  flash_block_erase=1'b0;
  flash_sector_erase=1'b0;
  write_addr=1'b0;
  case({s_stb_i&s_cyc_i,s_addr_i[2:0],s_we_i})//synthesis full_case parallel_case
   5'b1_000_0: flash_read_data=1'b1;
   5'b1_000_1: fifo_write_data=1'b1
   5'b1_001_0: read_status=1'b1;
   5'b1_010_1: write_addr=1'b1;
   5'b1_011_1: flash_chip_erase=1'b1;
   5'b1_100_1: flash_block_erase=1'b1;
   5'b1_101_1: flash_sector_erase=1'b1;
   default:
    begin
     flash_read_data=1'b0;
     fifo_write_data=1'b0;
     read_status=1'b0;
     flash_chip_erase=1'b0;
     flash_block_erase=1'b0;
     flash_sector_erase=1'b0;
     write_addr=1'b0;
    end
      
  endcase
end

wyqkiss

汗，你的代码写的真牛叉

AmoiBB

每一个信号都用一个always块来写，没必要用case吧

zpsky

谢谢各位指导。

zpsky

我想知道这样为什么不行？

tt

只保留case block,肯定就不会有latch.
否则从逻辑上看你就不是个组合逻辑.