Bidirectional GPIO using EMIO

Question

I am working on a project that requires a large number of bidirectional GPIO pins so I have to use EMIO instead of MIO to get access to the FMC Carrier Card PMOD pins.

I have GPIO output working on the EMIO pins by setting the GPIO_O port as external and configuring the sites in Implemented Design.
But how can I make the pins bidirectional? The PS block doesn't have a GPIO_Bidirectional port.

zedhed · Accepted Answer

Hi bb,

I am going to assume that you are using Vivado Design Suite for your design and that bidirectional means that there is an input, an output, and a tristate signal which can connect to an IOBUF primitive so that you can select which direction the GPIO is intended to go.

In your block design, you can enable EMIO GPIO from the PS7 IP configuration window which enables a set of EMIO GPIO ports (likely named GPIO_0) on the PS7 block.

You can then right click on that GPIO_0 port (all of the wires are grouped together) and select "Make External" to create an external port for them and automatically connect wires to the external port. I like to name my EMIO GPIO ports "emio_user" since I usually connect them to the user LEDs, DIP switches, and Push Buttons of a board for demos.

That's it!

When you create the wrapper for the block design, Vivado automatically picks up on the GPIO_I, GPIO_O, and GPIO_T signals and tries to pack them into IOBUF primitives for you, like this:

emio_user_tri_iobuf_8: component IOBUF
     port map (
      I => emio_user_tri_o_8(8),
      IO => emio_user_tri_io(8),
      O => emio_user_tri_i_8(8),
      T => emio_user_tri_t_8(8)
    );

Now all you need to do is to make sure that you have the matching constraints for those external nets and you have bidirectional ports.

Regards,

-Kevin

Bidirectional GPIO using EMIO

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