1. Basic principles of component selection

a. The principle of universality:

If the selected components have been widely used and verified, try to use less unpopular and biased chips to reduce development risks.

b. Principle of high cost performance:

In the case of similar functions, performance, and usage, try to choose components with better prices to reduce costs.

c. The principle of purchasing convenience:

Try to choose components that are easy to buy and have a short lead time.

d. Principles of sustainable development:

Try to choose components that will not be discontinued for the foreseeable time.

e. Substitute principle:

Try to choose components with more pin-to-pin compatible chip brands.

f. Principle of upward compatibility:

Try to choose components that have been used in previous products.

g. Principles of resource conservation:

Try to use all the functions and pins of the component.

The selection process of the chip is a compromise between various dimensional considerations.

Second, the whole process pays attention to chip attributes

1. When we select models, we need to consider the situation of trial production and the situation of mass production.

The price, delivery cycle, and sample application for small batch purchases; at the same time, it is necessary to pay attention to the price and delivery cycle after large batches. It is possible that after the batch becomes larger, the price of the supply has no advantage, or after the batch is large, the production capacity is insufficient.

In addition, according to your actual procurement situation, find a supplier of the corresponding magnitude. For example, the original factory often does not supply directly, and needs to go through an agent. Some agents have requirements for the level of supply.

At the same time, because there are not many scenarios in which the chip is used in the entire industry, the price of Taobao is very expensive, which is simply unacceptable. At the same time, a friend who sells chips said that due to the large-scale use of drone manufacturers, some people are frying the price of this chip, so it is difficult to buy it.

2. Pay attention to the matching between the life cycle of the device itself and the product life cycle.

For communication equipment, it is generally required that the devices we choose have a life cycle of more than 5 years, and there are follow-up complete product development roadmaps.

For example, a new hardware platform was used at that time, and during product planning, it was used to replace a mature platform with a shipment volume of millions of single boards. Due to the relatively long switching cycle, new products will only be gradually increased after 1 to 2 years after the completion of development. One of the DSP boards, the peripheral storage is SDRAM. When the product was ready to be sold, several major memory chip manufacturers such as Micron announced the suspension of production. As a result, as soon as the product was launched, a large number of inventory chips were hoarded, and small factories in Taiwan were found for device replacement.

Therefore, when selecting devices, it fully reflects "people who have no foresight must have near-term worries".

3. In addition to considering functions and laboratory environments, it is also necessary to consider the scenarios of the entire life cycle.

3. Specific selection, processor selection

To choose a processor, there are many factors to consider, not only the pure hardware interface, but also the relevant operating system, supporting development tools, emulators, as well as the engineer's microprocessor experience and software support, etc. .

Considerations for the selection of embedded microprocessors: In product development, the microprocessor as the core chip has high expectations for its own function, performance, and reliability, because the richer its resources and the more powerful its own functions, the better the product. The shorter the development cycle, the higher the project success rate. However, it is impossible for any microprocessor to be perfect and meet the needs of every user, so this involves the problem of selection.

1. Application areas

Once the function and performance of a product are customized, its application field is also determined. The determination of the application field will narrow the selection range. For example, the working conditions of products in the industrial control field are usually harsh, so the working temperature of the chip is usually wide, so industrial-grade chips must be selected, and civilian-grade chips are used. Excluded. At present, the more common application fields are classified as aerospace, communication, computer, industrial control, medical system, consumer electronics, automotive electronics, etc.

2. Bring your own resources

Often see or hear the question: What is the main frequency? Is there a built-in Ethernet MAC? How many I/O ports are there? Which interfaces does it come with? Does it support online simulation? Does it support OS and which OS can it be supported? Is there an external storage interface? ...the above all involve the issue of chip resources. What kind of resources the microprocessor comes with is an important consideration in the selection. The closer the chip's own resources are to the needs of the product, the simpler the product development will be.

3. Scalable resources

The hardware platform needs to support OS, RAM and ROM, and the resource requirements are relatively high. Chips generally have built-in RAM and ROM, but their capacity is generally very small, even if the built-in 512KB is large, but the running OS is generally above megabytes. This requires the chip to expand the memory.

4. Power consumption

Just looking at "power consumption" is a relatively abstract term. Products with low power consumption can save energy and money, and can even reduce environmental pollution and increase reliability. It has so many advantages, so low power consumption has also become an important indicator in chip selection.

5. Packaging

Common microprocessor chip packages mainly include two types: QFP and BGA. BGA type package soldering is more troublesome, and general small companies will not solder it, but the chip size of BGA package will be much smaller. If the product does not have strict requirements on the chip size, it is best to choose a QFP package when selecting a model.

6. The continuity of the chip and the inheritability of the technology

At present, the speed of product replacement is very fast, so the upgradeability of the chip should be considered when selecting models. If it is a chip of the same core series from the same manufacturer, its technology can be inherited better. You should consider well-known semiconductor companies, and then inquire about their related products before making a judgment.

7. Price and Availability Guarantee

Chip price and availability are also factors that must be considered. Many chips are currently in the trial stage (sampling), and their prices and supply will be in an unstable state, so try to choose chips with mass production when selecting models.

8. Emulator

The emulator is a tool used for hardware and low-level software debugging. If it is not available in the early stage of development, it will basically be difficult to do anything. Choosing a suitable emulator will bring a lot of convenience to the development. For people who already have an emulator, consider whether it supports the chosen chip during the selection process.

9. OS and development tools

As a product development, it is necessary to consider its support for software when selecting chips, such as what kind of OS is supported. For people who already have an OS, in the selection process, it is necessary to consider whether the selected chip supports the OS, or it can be said conversely, that is, whether the OS supports the chip.

10. Technical Support

The current trend is to buy services, that is, to buy technical support. A good company's technical support capability is relatively guaranteed, so it is best to choose a well-known semiconductor company when selecting chips.

In addition, the maturity of the chip depends on the scale and usage of the user. If you choose a chip that is widely used on the market, there will be more shared resources, which will bring a lot of convenience to development.