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Altera_Forum
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12 years ago

assigning DE2 switches to inout port

Hello all,

I am building a custom microcontroller. I just tried to implement GPIO ports. The microcontroller entity has multiple ports as inout. This works fine in simulation, but in 'reality' on a DE2 board a problem occurs. Connecting it to the 7-segment displays and LEDs is no problem, but connecting it to the switches I get a message telling me that I have multiple drivers. I understand why this happens, but don't know how to fix it. Could you help me on my way?

13 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    On the top level as in. In the pin-planner the same (Input) as is specified in the "board-port" csv file.

  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    Well I think it actually doesn't make sense to have this error because you're using this pins.

    Could it be that have duplicated lines of your custom microcontroler instance in the top level?

    Can you paste the exact same message Quartus shows in the log? If the message is collapsed, please copy the sub-level messages also.
  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    Concerning the duplicated lines, I don't think so. I've checked multiple times.

    The error message is as follows:

    Error (13076): The node "microcontroller:ASIC|memory:memory0|GPIO_memory:GPIO_memory0|data_int" has multiple drivers due to the non-tri-state driver "SW[0]"

    This is the same for all switches used in this manner.
  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    I might add that the direction of the inout is controlled by setting or clearing a bit in a register.

  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    No I haven't but I'm not sure what you mean. SW is a std_logic_vector(17 downto 0).

  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    When I want to use inout signal in a component, usually I do this way:

    pin_o : std_logic;

    pin_i : std_logic;

    pin_oe_n : std_logic;

    Then I can connect it to the top level pin this way:

    pin_i <= sw(0);

    sw(0) <= pin_o when (pin_oe_n = '0') else 'Z';
  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    Got rid of the error by creating extra tristate drivers inbetween the SW and the GPIO port of the microcontrollers with the direction set by an extra switch worked. This setup doesn't work though, but I might be able to figure out why.

  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    --- Quote Start ---

    When I want to use inout signal in a component, usually I do this way:

    Then I can connect it to the top level pin this way:

    pin_in <= sw(0);

    sw(0) <= pin_out when (pin_oe_n = '0') else 'Z';

    --- Quote End ---

    This is already done in the microcontroller entity.