How to use boolean to control switch with fixed point data.

I am trying to use a boolean output from inside of Matlab function block to control a switch, which has 16-bit fixed point data. However, I keep getting the following error:

This assignment writes a 'logical' value into a 'double' type. Code generation does not support changing types through assignment. Check preceding assignments or input type specifications for type mismatches. Function 'FSM' (#1424.358.366), line 20, column 13: "path_sel" Launch diagnostic report.

It appears to force my output into a double type and fails. I noticed if I leave the switch data inputs open (floating) it runs fine and interprets the switch states as T and F.

Answer 1

[Fangjun Jiang]

You set the criteria of the Switch block as u2>=1, which implies that u2 is double data type. Through back propagation, it requies "path_sel" to be double.

Just change the criteria of the Switch block to be "u2~=0"

[Joshua Wright]

Thank you for the suggestion. I updated the criteria as suggested but receieve the same errors and double propagation as before.

[Fangjun Jiang]

check the z delay block to see if somewhere "double" is specified. It should output a 'boolean' just as "fftlk_valid".

[Joshua Wright]

Did not see any speicification on the delay unit. I tried removing the delay and directly connecting but had the same errors.

Answer 2

[Bharath Venkataraman]

S1 and S2 when they are assigned to mealy_state_reg likely need to be fixed point.

Try using assignements as follows:

mealy_state_reg(:) = S1;

mealy_state_reg(:) = S2;

[Joshua Wright]

I added a convert block to ufix1 and that resolved the issue.