How to adjust the size of block.outputport.data in Matlab? - matlab

Question

I have tried to generate a square pulsed clock. But it gives error. I tried this:
function pll( block)
setup(block);
function setup(block)
% Register number of ports
block.NumInputPorts = 1;
block.NumOutputPorts = 1;
% Override input port properties
block.InputPort(1).Dimensions = 1;
block.InputPort(1).DatatypeID = 8; % boolean
block.InputPort(1).Complexity = 'Real';
block.InputPort(1).DirectFeedthrough = false;
% Override output port properties
block.OutputPort(1).Dimensions = 1;
block.OutputPort(1).DatatypeID = 0; %double
block.OutputPort(1).Complexity = 'Real';
block.NumDialogPrms = 1;
block.DialogPrmsTunable = 0;
ts = 1/24000000'; %'
block.sample times= [ts 0];
block.SimStateCompliance = 'DefaultSimState'
function Outputs(block)
t = [0:1/(24000000):0.000001];
l = 0.1*exp(-6);
c = 220*exp(-9) + 60*exp(-9);
f = 1/(2*pi*sqrt(l*c));
block.OutputPort(1).Data = square(2*pi*f*t);
function Terminate(block)
But it gives me the error
"Error evaluating registered method 'Outputs' of M-S-Function 'pll' in
'untitled/Level-2 M-file S-Function'. Invalid assignment in
'untitled/Level-2 M-file S-Function': attempt to assign a vector of
width 24001 to a vector of width 1."
the error indicates on the line
block.OutputPort(1).Data = square(2*pi*f*t);
so what can be done to overcome this error?

Answer 1

It seems from your example that you're not really familiar with the way Simulink works. At each time step, each block in a Simulink model outputs a value (i.e the block's output value) corresponding to the current simulation time. In your case, within the block.Output function you are trying to output all time points at every simulation time step.
It appears that what you really want is to replace
t = [0:1/(24000000):0.000001];
with
t = block.CurrentTime;
And replace
block.OutputPort(1).Data = square(2*pi*f*t);
with
block.OutputPort(1).Data = sign(sin(2*pi*f*t));
Also, some other things to consider:
you don't seem to be registering the block's output method using:
block.RegBlockMethod('Outputs',#Output);
Why have you defined the block to have an input when it doesn't seem to require one?
Why are you doing this in an S-Function when a From Workspace block (or one of the many other ways to get data into a model) would seem to make more sense?