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VitPri's avatar
VitPri
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3 years ago

Conbinational group instead of regestered group

Hi all, I am new to FPGA and Quartus and just truing to work with it. I am using Quartus Prime Lite edition 22.1. on Win 10. I write a sample module with 3 always block doing just simple stuff....
FvM's avatar
FvM
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3 years ago
Where do you see variable classification as registered or combinational? All variables assigned in a clocked always block are inferring registers, so the variables in the example codes. However, due to the usage of blocking assignments, some variables are also used to hold combinational intermediate results, e.g. bit in the last block. The registered value is first increased, than the new value is immediately used as index and in a compare operation. The last assigned value is written to register again when exiting the always block.
VitPri's avatar
VitPri
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3 years ago

Hi FvM,

I am checking status of variables in waveform editor when I am trying to add variable to watch them. And in main code when you are right click on variable -> locate node and if it is registered group you can see menu locate in ... and if it is combinational group - locate node menu are not accessible.

So is it possible to avoid this or fix it? And why first 3 variable are registered and any other not? Declaration and usage are the same.

thank you