Syntehsizable VHDL Code

I read Ashendens book about VHDL, but I recognized, that not everything can be synthesized . How can I know which parts of VHDL are synthesizable and which not ?

Best you refer to J.Bhaskar. ”A VHDL primer”. Addison Wesley book!

Hi Osbourne,

I’m not being mean too you, I understand that you are starting out using HDL’s this is really a comment on many of the questions that I’ve read on this forum, so please don’t be offended!

In a recent post about the hot areas to work in, verification seemed to be a common thread, this was attributed to increasing complexity, I wonder how much of this is really because of falling skills in writing the HDL in the first place!

Don’t go and read about what someone else thinks can be synthesised, just think about it, it will become obvious!

If your want to write HDL’s effectively you MUST first be able to design digital circuits. If you understand what a circuit can do then you will know what you can synthesis and what you cant.

I’m writing this in an attempt to help you on your way to writing good HDL, its not as a criticism.

Just remember what HDL actually stands for, describe the hardware you want and not some abstract idea of what you want a piece of code to do.

I think that this is the most valuable bit of advice you will hear about writing a HDL, “write a description of the hardware that you want”

I’d suggest that you write down what you want a device to do, describe it in a HDL then post both the description and the VHDL here and ask for advice.

I will help out and I’m sure many others would too (I’ve had some great advice from this forum)

Kind regards, and good luck with it Bob

hi,
introduction to vhdl by douglus perry is the good book for vhdl synthesis.

with regards,
srik.

Hi Engineer_Bob,

Hey, this is really good advice. The way you put down is very good.

I'll keep tht in my mind.

Thanks
no_mad

osbourne said:

I read Ashendens book about VHDL, but I recognized, that not everything can be synthesized . How can I know which parts of VHDL are synthesizable and which not ?

Click to expand...

Please re-read the book again because the author never pretended that everything is synthesizable ..
There are some very obvious stuff that can't be synthesizable like physical types for example !! .. how can u model a thermometer and u get synthesized !! .. how can u synthesize the degree ? ..