Boolean port

[Dan]

I'm trying to simulate an entity that has a boolean output port, but
ModelSim alerts me with this message:

"Types do not match between component and entity for port <port_name>"

(Filename "Name_of_my_entity_timesim.vhd" Line 30)

I opened that file and I notice that the boolean signal is represented as
std_logic_vector (0 downto 0)

?

I worked around the problem using a std_logic type instead of boolean, but I
would like to know about other suggestions.

Is this a known problem when simulating boolean signals?

Thanks,

 

[Jonathan Bromley]

I'm trying to simulate an entity that has a boolean output port, but
ModelSim alerts me with this message:

"Types do not match between component and entity for port <port_name>"

I opened that file and I notice that the boolean signal is represented as
std_logic_vector (0 downto 0)

?
Is this a known problem when simulating boolean signals?

It's a known problem when ports on a component and
an entity are of different type

Was the component automatically generated in some way
from the entity? If so, the automatic tool is buggy.

Read my lips: VHDL IS A STRONGLY TYPED LANGUAGE.
boolean != std_logic
std_logic != std_logic_vector(0 downto 0)

There's nothing wrong with using boolean signals, provided
you are happy for your simulations to use 2-state logic.
But a port of boolean type can only be connected to a
signal of boolean type, and so on. And the data types of
ports on component and entity must match, or else must
be type-converted in a configuration's port map.

You may find it's less hassle to use direct instantiation,
so that you don't use components at all. You then need
only to concern yourself with matching signal types to
the types of ports of the entity.
--
Jonathan Bromley, Consultant

DOULOS - Developing Design Know-how
VHDL * Verilog * SystemC * e * Perl * Tcl/Tk * Project Services

Doulos Ltd., 22 Market Place, Ringwood, BH24 1AW, UK
(e-mail address removed)
http://www.MYCOMPANY.com

The contents of this message may contain personal views which
are not the views of Doulos Ltd., unless specifically stated.

 

[Andy]

I'm trying to simulate an entity that has a boolean output port, but
ModelSim alerts me with this message:

"Types do not match between component and entity for port <port_name>"

(Filename "Name_of_my_entity_timesim.vhd" Line 30)

I opened that file and I notice that the boolean signal is represented as
std_logic_vector (0 downto 0)

?

I worked around the problem using a std_logic type instead of boolean, but I
would like to know about other suggestions.

Is this a known problem when simulating boolean signals?

Thanks,

If you use a boolean port at the top level of your RTL (synthesizable
code), then the gate level model will change to std_logic. I suspect
this may be related to your problem. Are you trying to use a
configuration to bind your testbench to your gate level model? Look up
port (or type) conversion functions. They can be called in the port
map of the UUT in the configuration of your testbench.

Andy