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Altera_Forum's avatar
Altera_Forum
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15 years ago

problem of LCD controller

hi,

i would convert a verilog code to vhdl code ,

//code verilog

always@(posedge iCLK or negedge iRST_N)

begin

if(!iRST_N)

begin

LUT_INDEX <= 0;

mLCD_ST <= 0;

mDLY <= 0;

mLCD_Start <= 0;

mLCD_DATA <= 0;

mLCD_RS <= 0;

end

else

begin

........

-----------------------------------------------------------------------

--vhdl code

process(iCLK,iRST_N)

variable var_mDLY : std_logic_vector(17 downto 0);

begin

if (( iCLK 'event and iCLK='1') or (iRST_N 'event and iRST_N='0')) then

if(iRST_N='0') then

LUT_INDEX <=(others =>'0');

mLCD_ST <=(others =>'0');

mDLY <=(others =>'0');

mLCD_Start <='0';

mLCD_DATA <=(others =>'0');

mLCD_RS <='0';

else

............

when i compile this error appear:

Error (10628): VHDL error at LCD_TEST.vhd(61): can't implement register for two clock edges combined with a binary operator

so if somebody have any solution ?

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    The Verilog always block can't be translated line by line, the syntax for a synchronous process with asynchronous reset is somewhat different. In my opinion, it's more intuitive than the respective Verilog construct that uses the negedge keyword for a level sensitive condition. You can use the language templates in Quartus editor context menu to look up the correct VHDL syntax for common design constructs. 

    process(iCLK,iRST_N)
variable var_mDLY : std_logic_vector(17 downto 0);
begin
if iRST_N='0'  then 
  LUT_INDEX <=(others =>'0');
  mLCD_ST <=(others =>'0');
  mDLY <=(others =>'0');
  mLCD_Start <='0';
  mLCD_DATA <=(others =>'0');
  mLCD_RS <='0';
elsif iCLK 'event and iCLK='1' then -- you can also write rising_edge(iCLK) 
end if;
end process;
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    thank's for your reply

    the code compile correctly but there is no result in the LCD.

    because i would to creat a controller of LCD 16x2 in DE2

    i don't know what the origine of problem ? may be this part of initilization of

    LCD.

    but i would to ask you i can't add the falling_edge(iRST_N)?

    because the verilog code he use

    always@(posedge iCLK or negedge iRST_N)

    begin

    if(!iRST_N)

    begin
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    As I said, negedge doesn't actually mean an edge sensitive condition in this place. VHDL is more exact in this respect.

    There may be many reasons why the LCD controller code is not working. You didn't show the relevant parts of it. If you have a known working Verilog controller code, you don't need to translate it to VHDL. You can instantiate it as a component in your VHDL design
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    Thank you very much

    i try a whole code and i use some component in verilog, after that i found

    the mistakes in my code.

    i would know if you have any idea for create a master who can read/write in LCD ,i try with this code i compiled with no error but

    no result in the LCD

    you can See both attached files