How do I design my very own ARM based processors?

Question

I have several questions about how I would design my own ARM-based CPU?

• How does one start with an ARM license and end up with a package ready to be soldered on to a board?
• What do I get from ARM (I am sure they have multiple license options to dish out - Architecture License (Qualcomm Snapdragon style) and Core License (TI OMAP style))?
• What tools do I need to proceed once I have 'that something' from ARM?
• What do I send to the fab?
• I believe only certain foundaries are licensed to etch an ARM core on to a silicon wafer. Am I right?
• As a student, can I afford to do this on an FPGA? How do I get hands on experience for something like this?

Answer 1

Here is how companies do it:

1. Raise about US$10 million.
2. Negotiate with ARM to get a license. This will probably cost at least US$1 million.
3. Get the design files from ARM. It will likely be in some form of VHDL, Verilog, or an "encrypted" netlist.
4. Design your own chip using a mix of your own logic (for the peripherals) and what ARM gave you. This step will likely require some expensive CAD software and a small team of experts. Expect to spend at least US$5 million and several years.
5. Get the masks made for the chip itself. If you use any modern semiconductor process then this will run around US$1 million.
6. Get the chip itself made. Price varies, but should be less than US$0.5 million.
7. Debug the chip you created, fix the bugs, then go back to Step 5 until you have something that you can sell.

Here is how YOU do it:

1. Take a graduate level computer architecture course at your local university.
2. Take more courses in digital logic and whatever else.
3. Design a CPU from scratch in VHDL or Verilog.
4. Design another CPU from scratch.
5. Look at the ARM instruction set and design a compatible CPU.
6. Make your ARM-Compatible CPU work in an FPGA.
7. Don't distribute your VHDL/Verilog source code unless you want to be sued.
8. Use your ARM experience to write a good dissertation for your PhD.
9. Use your PhD to get a job at ARM, or TI, or whoever. Then repeat the process using the previous 7 steps on how a company does it.

Ok, so this list is a little tongue-in-cheek but it is basically correct. The point is, don't even bother dealing with ARM directly because odds are you don't have the money. And don't do anything that will get you sued by ARM either.

Answer 2

ARM has a University DesignStart Program. As a student, you can only access basic Cortex-M0 material. But if you are really interested, get your faculty involved and then you can have access to much more design material (Verilog FPGA code, Evaluation IP, Simulations, etc.)

Answer 3

Take a look at this ARM core on OpenCores.

Answer 4

The ARM Cortex-M1 (probably the simplest of the ARM processors) is the first ARM processor specifically designed to be implemented as a soft processor in FPGAs. It is optimized for the following FPGA types:

Actel (M1 ProASIC3 and M1 Fusion)
Altera (Cyclone-II, Stratix-III)
Xilinx (Spartan-3, Virtex-5)

ARM itself is making a Cortex-M1 Development Kit for Altera Cyclone III although it is a little pricey at $625 from DigiKey. You do get all of the ARM Cortex-M1 IP though, and a license to do development (plus a free royalty grant for 1000 boards for those going into production, pretty cool).

There may be some options for getting the IP by itself (perhaps they have an academic program, someone else mentioned a university program, but that was for the M0). Then you could buy a development board separately.

Here is some more information about the ARM Cortex-M1 on Altera.

Here's some information about putting a ARM Cortex-M1 on an Actel FPGA.

Meanwhile there is some interest in other versions of the ARM Cortex on FPGA; here is a paper from someone that implemented a ARM Cortex-M0 on a Xilinx FPGA.

Answer 5

You can now get access to the Cortex-M3 processor (and an extendable AHB/APB subsystem) through ARM's DesignStart program.

The Eval option provides an FPGA target (simulation is supported, with obfuscated RTL of the core, everything else in Verilog). This currently targets the ARM MPS2+ FPGA, with mbed support.

The Pro version (only available to companies/universities who can sign a license) allows manufacture, and includes the processor core in Verilog (this covers both Cortex-M0 and Cortex-M3).