MATLAB: Bus expansion subsystem block and HDL coder

HDL Coder

Hi, I am new to HDL Coder. I am attempting to implement a design that has a bus going through a delay block.

I am recieving the error, "… dekay' is a bus expansion subsystem block, which is unsupported."

How should I resolve this issue? is there a more appropriate delay block?

Best Answer

The good news: this construction is fully supported in R2014a, where HDL Coder has had substantial improvements in its bus support. Prior to R2014a the bus support in HDL Coder was limited and could not support a bus going through a unit delay block.

The only way to do this prior to 14a is to model the delay without buses. This essentially means:

Breaking the bus into into its component elements with a Bus Selector block
Running each bus element through the appropriate delay block
Combining the delayed version of each bus element back into a bus with a Bus Creator block

Related Solutions

MATLAB: Cell array expansion

This is the standard behaviour of Matlab:

x = {1, 2};
y = x{:};   % y is x{1}

You see the same method for:

a = rand(1, 10);
b = max(a);

Why is this equivalent? Because MAX replies 2 outputs as "x{:}" and if just the 1st is caught, the 2nd is ignored. Therefore these methods are equivalent also:

x = {1, 2};
[y1, y2] = x{:}
a = rand(1, 10);
[b1, b2] = max(a)

So I would not expect an MLint-warning for a standard behaviour.

MATLAB: How to remove the error : ‘bus output must be defined by bus object for hdl code generation’.

Bus support in HDL Coder through R2013b does require bus objects to be defined for each bus. So, you will have to create bus objects in the base workspace or the model workspace to define any buses you want to use during HDL code generation. You will need to figure out your specific syntax issues. In R1014a bus support in HDL Coder will be significantly enhanced; one of the enhancements will be the lifting of the bus object requirement.

With respect to matrices: HDL Coder has never had support for matrices; you will need to figure out how to reduce matrix operations to vector operations.

If action subsystems are also not supported by HDL Coder. You can use enabled or triggered subsystems to implement the same logic instead.

Best Answer

Related Solutions

MATLAB: Cell array expansion

MATLAB: How to remove the error : ‘bus output must be defined by bus object for hdl code generation’.

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