OpenCores

Serial UART

interface process #3

Open rfajardo opened this issue almost 16 years ago

Instead of making the process simply sensitive to SysClk, I would register the signals on the rising edge and make Read and Load combinational.

Read <= not (CS_N or RD_N);
Load <= not (CS_N or WR_N);
process(SysClk) begin

```
if (CS_N = '0' and RD_N = '0') then
```
```
   Read <= '1';
```
```
else Read <= '0';
```
```
end if;
```
```
if (CS_N = '0' and WR_N = '0') then
```
```
   Load <= '1';
```
```
else Load <= '0';
```
```
end if;
```

if Rising_Edge(SysClk) then

    if (Read = '1' and Addr = "00") then

```
       DataOut <= RxData;
```

    elsif (Read = '1' and Addr = "01") then

```
       DataOut <= CSReg;
```
```
    end if;
```

```
if Read = '0' then
```
```
   DataOut <= "ZZZZZZZZ";
```
```
elsif (Read = '1' and Addr = "00") then
```
```
   DataOut <= RxData;
```
```
elsif (Read = '1' and Addr = "01") then
```
```
   DataOut <= CSReg;
```
```
end if;
```
```
if Load = '0' then
```
```
   TxData <= "ZZZZZZZZ";
```
```
elsif (Load = '1' and Addr = "00") then
```
```
   TxData <= DataIn;
```
```
end if;
```

    if (Load = '1' and Addr = "00") then

```
       TxData <= DataIn;
```
```
       LoadTX <= '1';
```
```
    else
```
```
       LoadTX <= '0';
```
```
    end if;
```
end if; end process;

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