# HDL and the EE board

Question... Where to draw the line with regards to HDL on EE.SE? This is akin to Arduino questions that appear on EE.SE where most are migrated but some aren't.

VHDL & Verilog are used to describe logic that could target hardware (be it ASIC, FPGA etc...) but they are in essence a programming language. Thing is ... writing in VHDL/Verilog has both hardware & software considerations.

• SOFTWARE: how to describe a certain logical sequences
• HARDWARE: synthesis querks (Actel & if/elsif… tree’s), mapping onto an LUT, timing etc..

When you compare StackOverflow (SO.SE) there are 2743 VHDL tags & 2,390 verilog tags. When the same tags are compared on ElectricalEngineering (EE.SE) there are 668 VHDL & 601 verilog thus SO.SE is geared towards accepting VHDL/Verilog coding queries.

Not all of the EE.SO questions that are tagged VHDL or VERILOG are valid EE.SO queries. Take How to convert a floating point number to integer, using VHDL? shouldn’t this have been migrated to SO.SE

• You need to proofread this. There are enough typos to make it difficult to follow the point you're trying to make. VHD --> HDL? stackexchange --> stackoverflow? tags --> questions? flacid --> flaccid? etc., etc. – Dave Tweed Jan 4 '16 at 13:56
• Where are you even getting your tag numbers? You're of by a factor of 10 on the EE.se questions. – W5VO Jan 4 '16 at 14:50
• What is a "VHD"? – Olin Lathrop Jan 4 '16 at 14:52
• @W5VO there appears to be a difference between SO.se & EE.se w.r.t. tags... EE.se has info,newest,active (and active was selected) while this doesn't appear on SO.se. Hence being off by 10x on EE.se. Updated – JonRB Jan 4 '16 at 14:55
• @OlinLathrop typo ... should have been HDL (Hardware descriptive Language). muscle memory with regards to typing vhd as that is the file extension used by my firmware team – JonRB Jan 4 '16 at 14:57

HDL is on-topic on electronics.stackexchange.com. There is no line.

StackExchange can do what it wants with HDL questions, but there is no need to have a "line" that strictly sorts where a question goes. This is a case where there is some overlap between sites, and this is OK. You could ask that question here, or there, (but not both please) and both communities would give you a good answer.

Finally, StackOverflow is huge compared to our site, about 100x bigger (numbers). It doesn't make sense to compare the absolute values of numbers in many cases. How about comparing ratios or percentages?

Tag              | EE.SE  (out of 54k)        | StackOverflow (out of 11M)
verilog*         | 1.25% (673)                | 0.030% (3278)
vhdl*            | 1.24% (670)                | 0.025% (2743)
arduino*/hdl*    | 2.94  (3946/1343)          | 1.37   (8232/6021)


From these numbers, we clearly need more HDL questions to improve our arduino/hdl ratio. (joke)

On a more serious note, while SO is 100x bigger than our site, by population we do 100x more HDL questions.

• This is what I am querying. Forget about cross-posting for the moment (as that is just bad manners). There is a world of difference between a "how do you concatenate two vectors" and "why is my if/elsif/elsif... producing massive stp files" – JonRB Jan 4 '16 at 15:59
• Sure, there's a difference, but I don't think that there is value in placing an arbitrary dividing line in the middle of the topic. Consider also that SPICE simulations are on-topic, and some simulation environments (e.g. LTSpice) don't have a direct path to hardware. You can also make the argument that since you're programming a FPGA, you aren't doing "hardware", but that argument is painfully pedantic (and moot since we allow firmware questions). – W5VO Jan 4 '16 at 16:19
• Thats fine, that's why I asked as there is a grey area. If its consider all HDL is on topic that's clear – JonRB Jan 4 '16 at 16:21

Your perceptions seem to be somewhat skewed by the organization in which you're working. In the projects in which I've been involved, it's the hardware guys that are writing the HDL and the firmware guys that are writing the microprocessor code — sometimes for microprocessors that are embedded inside the FPGAs.

And I disagree that an HDL is "in essence a programming language." HDLs describe hardware, which is fundamentally parallel, while conventional programming languages are fundamentally sequential. It takes very different mindsets to do a good job in both.

• It's not just the organisation that I employed within, it is quite typical in large organisation. There are plenty of people that only write VHDL and do not do hardware design. This can easily be independently validated by browsing recruitment – JonRB Jan 4 '16 at 16:06
• That doesn't even make any sense. If you're writing VHDL, you are doing hardware design. If not, what exactly is your definition of "hardware design"? – Dave Tweed Jan 4 '16 at 16:07
• V&V are not doing hardware design, they are writing testbenches to validate someone's VHDL/Verilog implementation meets requirements ( which is describing hardware ). – JonRB Jan 4 '16 at 16:09