What is the value on the %DSP usage pin and why does it change?

Altair Forum User

Submitted by Joe on Wed, 11/18/2009 - 05:24 

I have a question about the %dsp usage pin on the DSPInterface block. When I run a diagram with a DSPInterface containing the path to my .out file, I connect the %dsp usagepin to a plot. After execution the plot shows some variation in the %dsp usage. How do I understand what the plot shows?

Altair Forum User

Submitted by Anders89 on Wed, 11/18/2009 - 05:30.

Hi Joe,
VisSim gives you the percentage of your sampling interval that is used to execute your compiled diagram. If the value is 50, then you are using 1/2 of your sampling interval. For example, if your sampling interval was 20 microseconds, then you could sample 2x faster (10 microseconds) or add more calculation to your diagram.

Variation in the time to execute your diagram can occur depending on the code path taken. If you have periodic functions, or conditional execution, small differences in timing can occur due few instructions executing or branch pipeline breaks. A