Error: System not scheduable

[mormathis]

Hi,

 

i'm currently working on a Battery Model in SystemC AMS. I have a working model in Simulink and now i try to adopt this system in SystemC AMS.

 

If i connect the current sinks TDF output with the model i get the following error:

Error: SystemC-AMS: System is not scheduable - last scheduable element: impuls

 

Do someone know what this error means and how i can solve my problem?

 

Thanks for you help

Mathias

 

 

[Martin Barnasconi]

I expect you have a loop (feedback path) in your design topology. This results in a circular dependency which cannot be resolved by the scheduler. To resolve this, add one time step delay, for example by specifying this delay in one of the output ports in the feedback path.

[mormathis]

Thank you very much for your hint. I added a delay of a time step and it worked out.

[Bruno]

Hi,

I got the same problem with the scheduling whilst modeling a PID controller with PWM and DC motor. However, adding the 1 step delay in the output port of the feedback path, caused another error:

SystemC-AMS: Access to sample >= rate not allowed for port: motor.in

I don't understand why I need to change the input rate. Any tips?
 

[Martin Barnasconi]

It looks like you have a multi-rate system, i.e. somewhere you defined a <port>.set_rate(..) in a set_attributes callback. Now you try to access the n-th sample at this port, like <port>.read(<sample>), but the nth sample is higher than the rate specified. This means you have either the wrong rate, or reading a sample outside the range defined by the rate.

[Bruno]

Thank you @Martin Barnasconi, 

That was exactly what it was happening. I had a <port>.read(<sample>) with a specific sample.