Two kinds of all right forms of IP kernel are offered to the customer: Soft core and hardcore. Both ways can make customers get the design that is proved functionally. The soft core is known as very comprehensive kernel too, need synthesizing and realizing on its SoC by the customer. And the hardcore has already been totally realized (finished the domain to design) ,Can be used for making directly. (Technically, realized after there is only production in a kind of design. But in this case, the ones that realize mean that arranges the overall arrangement and can be put into production directly) . SoC group only needs to put the hardcore into the chip like a one piece integrated circuit chip. Soft core and hardcore have different problems and advantages.

It needs a lot of steps to reach integration of IP kernel on a chip. Whether this course can be finished very easily, mainly depend on the delivery achievement offered. In addition, the customer not only must evaluate IP kernel but also assess IP provider.

Comparison with hardcore of the soft core

1. Characteristic

Because the soft core was not realized, it is more flexible than hardcore in view of function and realizing innately. On the other hand, the hardcore developer may spend more time optimizing their hardcore, because they should use in a lot of designs. So, this makes people think the hardcore will be offered more high characteristic.

In fact, for the high side, customizing the hardcore and can really offer the characteristic better than soft core completely of those most advanced technological design. Through using latching, dynamic logic, ternary signal, customizing the memorizer,etc., the whole custom design group can realize the result better than synthetic design of the complete static behavior. To needing SoC which reaches existing craft and terminal characteristic of designing technique, customize the hardcore and can meet these requirements better completely.

However, if the performance objective, within the range of a soft core, so hard nuclear advantage is unimportant. SoC can meet the performance requirement with soft core while designing the group, and utilize its inherent flexibility advantage. And with the technical progress of the craft, soft nuclear FTOP is limited and improved, make them become a kind of choice of more SoC designers'. Under the lower clock rate, perhaps the hardcore has advantage of area of the silicon dice. But the situation is not often like this. The method that the hardcore often uses ASIC briefly carries on solidification, make it unable to offer the advantage at the speed. Otherwise, customize kernels and can't pay optimizing again according to every generation of crafts completely, so has weakened the advantage on the frequency and size.

2. Technological independence and portability

One of the soft nuclear advantages is that the technology is independent, that is to say, Verilog or VHDL does not need to use a kind of particular technology or canonial cell library. This means the kernel of same IP can be applied to many kinds of designs, or in the existing future generation that designs. Some soft core providers adopt making, his non- independent design style technically of kernel, but this way can not see any advantage.

Fig. 1: The ones that are influenced by IP kernel develop the task.

On the other hand, the hardcore is very particular technically. In fact, if change its technological parameters or storehouse for the factory, the hardcore can't work normally. This has produced a risk, because while changing in technological parameters, IP provider needs to verify the hardcore again.

The hardcore can be transplanted to the new technology, but optimize in customizing completely again the nuclear work is take a lot of trouble as well as expensive. As to some advanced microprocessor kernels, this may take two years or more long time. So, the hardcore often carries on optical adjustment according to the new craft. Though this method is simple fast, it has reduced and customized a lot of advantages optimized completely to the existing craft from designing the group.

Moreover, optics adjusted and brought another risk at the same time, because it can only guarantee the new design meets the design rule, can't guarantee the accurate sequence inclusive or function, and prove again IP kernel that process optics adjusts is very difficult in an all-round way.

3. The speed / area / power is optimized

To technology to be realized, usually the running speed of the soft core more comparative than is faster on the hardcore. But even to the technology of this single, the hardcore is only directed against the optimization of a series of goals. If the goal is to make the chip area less at the reasonable characteristic, then to should use to this kind, the hardcore optimized for highly adjustable characteristic may be on too greatly.

Soft core can " Employ and optimize " (used after an attribute). Design for embedded SoC suitable to be particular, the sequence, area and power goal may need adjusting. For example: If SoC use clock of 200MHz, design, run soft IP kernel in 250MHz can switch over to running at 200MHz accurately. This has satisfied design constraint while receiving small dimension and more low-powered.

This kind of application optimizes and suitable for lower IO sequence too. Soft inner nuclear IO can adjust to restrain from, in order to the nuclear environment for use while cooperating accurately. If the hard kernel has outcoming signals of delays, SoC designer is almost unable to improve sequence.

If speed of SoC, area and power goal are in conformity with hard nuclear goal, then the hardcore will be extremely competitive. But to most designers, it has advantages even more that the soft core optimizes the respect for particular SoC.

4. Customizable

The soft core also has another advantage as to the hardcore: Compilation time customizes. These are that the design before realizing select.

The memory magnitude of the high speed buffer storage is the user-customized project of one common compilation time. According to the magnitude of the required high speed buffer storage of particular embedded application, the processor of the soft core can be accurate the ground cover is disposed. The hardcore can't be customized in this respect.

Another kind of applied customization project in a lot of soft cores is that the order is specialized, or a certain special order of selective support. For example, some SoC may need support to outside coprocessor. However, in not using these characteristic systems in some, the surplus hardware can be removed from the soft core, in order to save the area and power.