Re: Bus Interface

[ Follow Ups ] [ Post Followup ] [ ECE 532 Discussion Area ] [ FAQ ]

Posted by Michael van Dam on March 09, 1998 at 11:34:23:

In Reply to: Bus Interface posted by Howard Chou on March 08, 1998 at 14:56:25:

: I'm having problems when I try to connect my control
: registers to the data lines. I declared the data lines
: as INOUT mode, but when I connect all the registers
: together, I get an error saying that my data lines have
: multiple sources although my code ensures that only
: one source can drive the data lines at any time. Can
: anyone help me solve this? Thanks.

Inside your VHDL program, you cannot have multiple sources driving
the same pin, nor can you have multiple sources ASSIGNING a value
to the same pin.

I suspect you have multiple sources assigning 'Z' to the same output
pin, but this is not allowed because there is no internal tri-state bus.
Instead, you have to ensure that only one of your registers ASSIGNS
a value to the data pins at any given time.

Hope this helps.

Follow Ups:

Post a Followup

Name:
E-Mail:

Subject:

Comments:
: : I'm having problems when I try to connect my control : : registers to the data lines. I declared the data lines : : as INOUT mode, but when I connect all the registers : : together, I get an error saying that my data lines have : : multiple sources although my code ensures that only : : one source can drive the data lines at any time. Can : : anyone help me solve this? Thanks. : Inside your VHDL program, you cannot have multiple sources driving : the same pin, nor can you have multiple sources ASSIGNING a value : to the same pin. : I suspect you have multiple sources assigning 'Z' to the same output : pin, but this is not allowed because there is no internal tri-state bus. : Instead, you have to ensure that only one of your registers ASSIGNS : a value to the data pins at any given time. : Hope this helps.

Optional Link URL:
Link Title:
Optional Image URL:

[ Follow Ups ] [ Post Followup ] [ ECE 532 Discussion Area ] [ FAQ ]