choosing device, fpga, microblaze

[spartekus]

Hi all,
i dont have experience, maybe it is reason of my newbie question.
when we use microplaze, when we use fpga without microprocessor? or fpga always has microprocssor, connected? if yes, do we need to program microprocessor everytime, when we program a fpga?

i hope my question is not confusing, like my head now.

thanks

 

[barry]

Microblaze is a "soft" processor. This means it's a processor that's created using the general purpose elements of the FPGA. You have to intentionally instantiate the microblaze in your design to get it. There are other FPGAs that have dedicated (i.e., implemented in hardware) processors in them, also.

 

[xtcx]

Microblaze is a "soft" processor. This means it's a processor that's created using the general purpose elements of the FPGA. You have to intentionally instantiate the microblaze in your design to get it. There are other FPGAs that have dedicated (i.e., implemented in hardware) processors in them, also.

What do you mean FPGA with processor implemented in hardware?. Can you list some?. ACtel FPGA has Cortex ARM core, but that too is soft processor type more or less. Correct me if I am wrong

 

[xtcx]

Hi all,
i dont have experience, maybe it is reason of my newbie question.
when we use microplaze, when we use fpga without microprocessor? or fpga always has microprocssor, connected? if yes, do we need to program microprocessor everytime, when we program a fpga?

i hope my question is not confusing, like my head now.

thanks

You should read some basic info about soft processor and microblaze from sources like wikipedia which should help you understand what are they and how it works.
Simply stated, FPGAs are like a memory. You can create any logical structure you want say, a DSP\Microcontroller\ASIC. However based on your requirements, the outcome\efficiency may vary. For if you wanna design an ASIC like logic and use FPGA for that app, then you will be restricted with high speeds. If you wanna make DSP like FPGA, then you will have to face trouble with more multipliers, etc. Similarly if you want the FPGA to act as microprocessor, you can. Once you've ported the microprocessor core (Like IP core), it all looks like a normal uc programming only. your FPGA-uc will boot as soon as you program the FPGA, because the binary you program contains the microcontroller logic within

 

[barry]

What do you mean FPGA with processor implemented in hardware?. Can you list some?. ACtel FPGA has Cortex ARM core, but that too is soft processor type more or less. Correct me if I am wrong

Xilinx and Altera both have FPGAs with hard processors.

 

[spartekus]

thanks for your answer, i will read about what u said.
examples in intenet about microblaze are mostly with C and vhdl code together.
is it usefull or necessary to use C and vhdl together to program a microblaze? what can C do better than vhdl at programming of a microblaze?
thanks

 

[ads_ee]

The microblaze would be written in VHDL as it describes the soft processor's hardware logic. C is used to write software that will run on the microblaze.

It appears you need to read some basic information on the difference between hardware (digital logic) and software. You should also read more basic information on FPGAs.


Regards,
-alan

 

[spartekus]

Thanks Alan,
i know it is not right place to ask, i just didnt want to open another post on forum.
vhdl testbench, do we write it ourself, or program creat it?

- - - Updated - - -

"The microblaze would be written in VHDL as it describes the soft processor's hardware logic. C is used to write software that will run on the microblaze."
so we use both, but in different parts of design?

 

[ads_ee]

I don't remember if there was a TB produced by the SOPC builder tool. I remember we didn't use it if it was produced. We created our own BFM (bus function models) of the SOPC system to interact with the rest of the design and ran our own top level testbench of the entire FPGA design. The BFM just emulated the SOPC functions of the system.

"The microblaze would be written in VHDL as it describes the soft processor's hardware logic. C is used to write software that will run on the microblaze."
so we use both, but in different parts of design?

Yes you use both, the processor is implemented in VHDL and after the processor plus other logic is programmed into the FPGA (using e.g. an RBF file) you can run the C code on that processor.

 

[spartekus]

hallo again Alan,
which would be better choose to program a microblaze, C or C++? or it doesnt matter at all.

 

[ads_ee]

hallo again Alan,
which would be better choose to program a microblaze, C or C++? or it doesnt matter at all.

Depends on the microblaze compiler. I didn't do any of the programming of the FW so I couldn't say if the compiler supports C++. You'll probably have to look at the documentation on the tool chain used on Altera's web site.

 

[spartekus]

thanks i understood it.
a last question, are fpgas used to implement one of these(is it purpose of FPGAs), DSP,ASIC, microcontroller.. or are there any usage of fpgas without implementing any dsp, asic, microcontroller.
when i hear fpga programming, should i think, implementhing dsp, or asic or microcontroller.. sorry for newbie question. i need to make things to clear to start learning more motivated.
in other words, cant we do our work on fpga, without implementing microprocessor.

 

[xtcx]

thanks i understood it.
a last question, are fpgas used to implement one of these(is it purpose of FPGAs), DSP,ASIC, microcontroller.. or are there any usage of fpgas without implementing any dsp, asic, microcontroller.
when i hear fpga programming, should i think, implementhing dsp, or asic or microcontroller.. sorry for newbie question. i need to make things to clear to start learning more motivated.
in other words, cant we do our work on fpga, without implementing microprocessor.

No not necessarily. FPGAs acting as Micro processor\DSP\ASIC is an add-on feature marketed and enhanced in every newer versions of FPGA release by vendors, which will encourage many product vendors to buy and use it as a replacement. But however the basic design requirement for an FPGA remains same...

"More IOs + More Space for logics + High Speed interface + Programmable anytime anywhere"

Now it is upto the user to fit the FPGA into their requirements.
If you are to start from the scratch, really trust me;ignore all these and focus on VHDL\VERILOG for your RTL design and verification. In few years of experience you will understand what I mean.

-- Regards