Subject: Re: net_resolution (second iteration)
From: Kevin Cameron x3251 (Kevin.Cameron@nsc.com)
Date: Tue Feb 27 2001 - 10:03:35 PST
> From owner-verilog-ams@eda.org Tue Feb 27 09:41:33 2001
>
> --ian
>
> 8.10.1-3, 8.11
> - change "$driver" to "driver".
>
> 8.10.5
> - change title from "net_resolution" to "Driver-Receiver Access in Connect Modules"
> - replace body by:
> In a mixed net - that is, one containing discrete and continuous drivers and
> loads, the drivers and receivers of that net are decoupled. If both discrete
> drivers and loads are present on a mixed net, a bidirectional connect module
> (that is, one where the digital port is of type inout) is required.
I think that should be "can be used" rather than "required", I don't think
there is any reason that you can't use seperate D2A & A2D CMs instead. The
"bidir" CM is just an optimization - it works out both digital and analog
values at the same time and removes the need for A2Ds.
Kev.
> The outputs
> of the discrete drivers are combined using standard Verilog-D resolution mechanisms.
> This resolved value may be accessed in the connect module by reading the inout
> port. The loads can be driven by writing to the inout port. Although the
> same identifier is used for the input and output directions of the port,
> the effect is the same as if there were distinct, unidirectional, ports.
>
> No default processing is applied within a connect module. The output side of
> the digital port must be driven explicitly with a continuous assignment
> or equivalent (see following section for an example).
>
> When only discrete drivers, or loads, but not both, are present on a mixed net,
> no segregation takes place. In this case, the drivers can be accessed by reading
> (for an input port) and the loads can be driven by writing (for an output port).
>
> The information returned by the driver access functions shall exclude any
> drivers contributed by the connect module instance itself. For example, if the
> connect module instance adds a driver for the discrete output (or inout) port,
> this driver shall not add to the value returned by the driver_count() function.
...
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