Soft Processor Core

Hi ng,

im searching for a soft processor IP core with the following capabilities:

- Interrupt (more than one interrupt / e.g. saving registers in stack)

- 32 Bit ALU

- common Instructionset (e.g. MIPS or an open source assembler included)

- 'easy' to enhance special purpose registers and their neccesary additional instructions (e.g. Real Time Clock and load RTC-Register to Accumulator)

I found at many IP-Cores:

-miniMIPS: miniMIPS seems to be a good choice, but it doesn't fit in a Spartan3 - 200k Gates (108% of LUTs). Did i miss to adapt some Xilinx-specific synthesize-adaptions?

- CPUgen not very good commented source-code... and i think it can only handle one interrupt, right??

- Xilinx Microblaze (not free) does it really occupie only 1000 LUTs with a 32Bit ALU and multiple interrupts? Big disadvantage is the relative high prize of 75Cent per implemented core.

if you have some experience with soft processor cores, please help me with some suggestions.

thanks, stefan

Reply to
Stefan Oedenkoven
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Yes, MicroBlaze occupies 1000 LUTs. MicroBlaze is shipped as part of EDK which cost $495. There are no license fee or royalty fee with the usage of MicroBlaze as long as you have bought the EDK. The 75 cent is the cost of the 1000 LUTs that MicroBlaze occupies.


Reply to
Göran Bilski



there is one full SoC environment, all tools, simulator, debugger, plug and play bus - peripherals, etc... its all GPLed! (except the debug monitor)

look at GRLIB

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LEON3 based SoC is larger than Microblaze system :( S3-400 is smallest device where it fits at all, and that almost bare CPU and RAM system


Hm, I did smalles MB system synthesis, I think MB soc can fit into S2-100, into S3-200 it fits also, but not very much peripherals :(


CPUgen: that projects seems to be dead, if you have some arch of some .exe files and no full sources and if that has been static no updates for 6+ months, its dead (or not being public any more, other possibility)



:) the 75 cent is some marketing stuff, if could be the price of MB only in the cheapest cell/dollar device in 250,000 qty. in real applications the MB SoC price (FPGA fabric price...) would calculate a little above dollar at least, more likely several dollars (or more in small qty design).


Reply to
Antti Lukats


I found this statement in the MB FAQ:

  1. If I understand you correctly, after purchasing the MicroBlaze soft processor with the development kit for 5, we can use MicroBlaze in as many projects and products as we want? Yes. When you buy the MicroBlaze kit, you have a license to use the MicroBlaze processor in as many Xilinx FPGA designs as you want at that site. (A site is defined as a geographic location including a five mile radius.) There is no limit to the number of Xilinx FPGA projects in which you can implement MicroBlaze. There is no per device or project royalty.

What do they mean with this obscure site limitation? So for a big company (with departments >5miles away from each other) i need more licences over even for selling it to customers living somewhere >5 miles away? ;-) I've never seen such a clause...

Hmmm... but without the 'per instance' licence the mb-core becomes more attractive for me. Maybe you can tell me, if there is a online gate-count application for the mb-core. i can only find this 950 logic blocks minimum statement on the xilinx site. And is it possible to (easily) add own peripherals units (time capture/release arrays) to the peripheral bus of the mb?

regards, Stefan

Reply to
Stefan Oedenkoven

Stefan Oedenkoven wrote: (snip)

My guess, given that there is no per device cost, is that development machines need to be within the 5 mile radius. For $495 you can probably afford more than one if the company is spread out more.

That doesn't say anything about remote connections, either text only or remote viewing of graphics (such as VNC), from machines within the 5 mile radius. I would check for such restrictions, also.

-- glen

Reply to
glen herrmannsfeldt

I believe there is an open source version of microBlaze called Mblaze, IIRC. There are also tons of 32 bit risc cores that have been developed and are supported by versions of the gnu compiler, again IIRC. Check out

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Rick "rickman" Collins
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Reply to

I don't think we will go out and start measuring the distance at customer sites.

There are some tools (not Xilinx tools) which checks on what timezone you are in. I know since I tried to connect to a license server in San Jose, USA from my home in Sweden and the tool reported that the license didn't allow this due to that I was in a different continent.

It really depends on the target FPGA and what options you enable on MicroBlaze. There are too many combinations of targets and options to make this table easy to use. It's far more easier to implement what you want feature that you need in the tools and see what you get.

Yes, It's easy to do this in the tools. There are two different buses you can use for MicroBlaze. The OPB and the FSL. Which to use is depending on what you want to do.

Regards, Göran Bilski

Reply to
Göran Bilski

My bet is that it is for economy-of-tech-support reasons: With two distinct geographic locations, Xilinx probably figures that the tech support load is increased as opposed to a single co-located development shop where you are more likely to ask a coworker first.

Nicholas C. Weaver.  to reply email to "nweaver" at the domain
Reply to
Nicholas Weaver

Don't forget to look at the Altera's NIOS II. You can buy a developers kit (board and development tools) for about $1000.00. You can download Quartus II Webpack and NIOS II Evaluation from their website.


Reply to
Derek Simmons

Hi Göran & Nicholas,

thank you for this infos. i think for further details i'll contact your colleagues in the Munich office.

regards, stefan

"Göran Bilski" schrieb im Newsbeitrag news:cnb8j8$








Reply to
Stefan Oedenkoven

Just back from an practical "hands-on" seminar on Microblaze. Didn't try that during the lab session, but was said that a reference design exists for a Spartan 3-50 fit (just 2 slices free!). Obviously it's very limited, but it works. Something like 766 slices... they said it can be really routed.

In my opinion, Mb excels when you need also some hardware co-processing functions made by surrounding FPGA logic, so you need some more free space, beside the core.

Reply to
Antonio Pasini

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