Homemade flash drive. Homemade flash drive Electrical circuit of a flash drive

Today, flash drives are the most popular external storage media. Unlike optical and magnetic disks (CD/DVD and hard drives, respectively), flash drives are more compact and resistant to mechanical damage. How were compactness and stability achieved? Let's find out!

The first thing to note is that there are no moving mechanical parts inside the flash drive that could be damaged by falls or shocks. This is achieved due to the design - without a protective case, the flash drive is a printed circuit board to which a USB connector is soldered. Let's look at its components.

Main Components

The components of most flash drives can be divided into main and additional.

The main ones include:

1. NAND memory chips;
2. controller;
3. quartz resonator.
4. USB connector

NAND memory
The drive works thanks to NAND memory: semiconductor chips. Chips of such memory, firstly, are very compact, and secondly, very capacious: if at first flash drives were inferior in capacity to optical disks that were common at that time, now they even exceed Blu-Ray discs in capacity. Such memory, among other things, is also non-volatile, that is, it does not require a power source to store information, unlike microcircuits random access memory created using similar technology.


However, NAND memory has one disadvantage compared to other types of storage devices. The fact is that the service life of these chips is limited by a certain number of rewrite cycles (steps of reading/writing information in cells). On average, the number of read-write cycles is 30,000 (depending on the type of memory chip). This seems like an incredibly long time, but in reality it is equal to about 5 years of intensive use. However, even if the limit is reached, the flash drive can continue to be used, but only for reading data. Additionally, due to its nature, NAND memory is very vulnerable to electrical surges and electrostatic discharge, so keep it away from such hazards.

Controller
Number 2 in the figure at the beginning of the article is a tiny microcircuit - a controller, a communication tool between flash memory and connected devices (PCs, TVs, car radios, etc.).


A controller (otherwise called a microcontroller) is a miniature primitive computer with its own processor and some RAM used for data caching and service purposes. The procedure for updating firmware or BIOS means updating the microcontroller software. As practice shows, the most common failure of flash drives is controller failure.

Quartz resonator
This component is a tiny quartz crystal, which, like in an electronic watch, produces harmonic oscillations of a certain frequency. In flash drives, a resonator is used for communication between the controller, NAND memory and additional components.

This part of the flash drive is also at risk of damage, and, unlike problems with the microcontroller, it is almost impossible to solve them yourself. Fortunately, resonators in modern drives fail relatively rarely.

USB connector
In the vast majority of cases, modern flash drives have a USB 2.0 type A connector, oriented towards reception and transmission. The newest drives use USB 3.0 Type A and Type C.

Additional components

In addition to the main components of a flash storage device mentioned above, manufacturers often provide them with optional elements, such as an LED indicator, a write-protect switch and some features specific to certain models.

Led indicator
Many flash drives contain a small but quite bright LED. It is designed to visually display the activity of a flash drive (writing or reading information) or is simply a design element.


This indicator most often does not carry any functional load for the flash drive itself, and is, in fact, needed only for user convenience or for beauty.

Write protect switch
This element is more typical for SD cards, although it is sometimes found on USB storage devices. The latter are often used in a corporate environment as carriers of various information, including important and confidential ones. To avoid incidents with accidental deletion of such data, flash drive manufacturers in some models use a protection switch: a resistor that, when connected to the power supply circuit of the storage device, does not electric current access memory cells.


When you try to write or delete information from a drive that has protection enabled, the OS will display the following message.

Protection is implemented in a similar way in so-called USB keys: flash drives that contain security certificates necessary for the correct operation of some specific software.

This element can also break, resulting in an annoying situation - the device seems to be working, but it is impossible to use it. We have material on our website that can help solve this problem.

Unique components

These include, for example, the presence of Lightning, microUSB or Type-C connectors: flash drives with these are intended for use, including on smartphones and tablets.

How does a flash drive work?

Flash drives, or USB flash drives, are devices for storing, writing and reading information. Thanks to them, we can carry huge amounts of data in our pockets: photo albums, music concerts, price lists, maps, presentations, etc. But how does this become possible? Let's talk in this article about how a flash drive works.

How does a flash drive work: device

The simplest flash drive is designed for at least 10,000 rewrite cycles. But the best specimens can withstand 100,000 cycles. If you do not rewrite information several times a day, this resource could last for an unlimited time. However, data is usually stored for no more than 10 years. As a rule, during this time people manage to replace the drive several times with a more modern device.

And yet, sometimes it happens that a flash card suddenly fails: when connected, the computer “does not recognize” it, reporting that it is an “unknown device.” To understand, you need at least general outline represent her device.

Several blocks fit inside a small flash drive:

• microcontroller;
• flash memory microcircuit (chip);
• clock source - quartz resonator;
• Light-emitting diode;
• write protect switch.

The main part is the memory matrix. It consists of many cells in which information is recorded. One cell - 1 bit of information. The computer uses binary logic: it operates exclusively with zeros and ones. There is voltage in the cell - one, no voltage - zero. In order to write down one character - a letter, a number, a space, etc. - you need 8 bits or 8 cells. 8 bits are called a byte. Each flash drive can store millions of bytes of information.

The main advantage of the memory matrix is ​​that data is not lost when there is no supply voltage, i.e. it is energy independent.

The controller controls the operation of memory cells; this is the drive's control unit. When connected, the controller passes current through all cells, checks where 0 is written and where 1 is written. The signal from the computer enters it through the connector.

In accordance with this request signal, the control unit accesses exactly those cells that are specified in the request and allows the data recorded in these cells to enter the computer. Or vice versa, the controller reads data from the computer and sends it to the selected cells.

For normal functioning of the flash drive you need clock frequency, which is generated by a quartz resonator. It is he who sets the speed of the flash drive.

What to do to make the flash drive work without failures

Never remove the flash drive from a running computer. You must first disable it. In these cases, the computer writes that the memory device can be removed. This means that a shutdown signal was received from the computer to the controller, and the corresponding service information was recorded in the control unit.

If you pull out the flash drive without turning it off, the service information in the controller may be lost, and then it will no longer be able to connect to the reading device. The same thing can happen when sharp changes voltage.

The controller is the most vulnerable part of the flash drive. A high-quality memory matrix and crystal oscillator almost never fail. To destroy them, you need to either break the USB device or apply very high voltage. But the connector can be damaged if you handle it carelessly.

How to recover deleted files from a flash drive? What is the difference between flash drives and external hard drives? How to recover data?

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In the modern computer world, it is difficult to find people who have not heard of flash drives. However, many still do not have a complete understanding of these devices. In this material we will fill this gap and talk about the main parameters and characteristics of USB drives.

Introduction

IN present time It’s hard to find people who haven’t heard of electronic devices such as flash drives or simply “flash drives.” Technical characteristics and optimal shape allowed them to take a leading place among portable storage media, and practically replace optical disks and floppy disks.

However, despite the popularity of flash drives, not all users have a complete understanding of these devices. In this material we will try to fill these gaps so that you can independently choose the appropriate flash drive for yourself in any computer store.

As is the case with other storage media, flash drives have a number of basic technical characteristics by which they are selected. Let's look at the main ones and figure out what you should pay attention to first when buying a flash drive.

What is a flash drive

A flash drive is a storage device with a USB connection interface that uses non-volatile flash memory to store information. The main advantages of flash memory include its low cost, compactness, noiselessness, mechanical strength, operating speed and low power consumption. Thanks to all these advantages and ease of use, flash drives have become quite a short time gain popularity among users and displace other competing solutions from the market.

The main purpose of compact USB drives is to store, exchange and transfer data that is not too large. In addition, flash drives can be used to store backups and download operating systems. At the same time, flash drives can be connected not only to a computer, but also to various household appliances, for example, TVs, players, record players and others with USB connectors.

Despite all its advantages, flash memory still has a number of certain disadvantages. First of all, this is a limited number of cycles of writing/rewriting information (up to 10 thousand times for MLC memory, which is installed in most devices, and up to 100 thousand for SLC type memory). Flash drives also have a limited storage life. And although most manufacturers claim that their products can store data for 10-20 years, in fact, the company warranty for this type of media is no more than 5 years.

Like any low-voltage electronics, flash memory is very sensitive to electrostatic discharges, which are quite common in everyday life. Another reason for the fragility of a flash drive can be the USB connector, which can simply break due to frequent connection/disconnection of the media.

True, all these shortcomings do not prevent flash drives from remaining for many years one of the most common storage media and favorite means of transferring data among ordinary users.

Flash storage capacity

Volume is one of the key characteristics of any data storage device, since it directly determines how much information can fit on the media. That is why most ordinary users, when purchasing storage media, primarily focus their attention on this parameter.

The first flash drives had rather modest volumes, amounting to tens or hundreds of megabytes. Modern flash drives in this regard are far ahead of their predecessors, and today the minimum volume of a cheap USB drive can be considered 4 GB or even 8 GB, since there is practically no difference in price between them. The most popular sizes at the moment are considered to be 16 and 32 GB, since the cost of such flash drives is still not high and amounts to less than 1000 rubles.

As you may have already noticed, the amount of flash memory, like RAM, is a number obtained from two raised to the nth power (2 n). That is, each subsequent value is obtained by doubling the previous one. Therefore, after 32 GB, the volume of flash drives begins to grow rapidly, and along with them, their cost begins to increase very significantly. So, if USB drives measuring 64 GB and costing about 1,500 rubles are still in active demand, then 128 GB flash drives can have a price of over 3,000 rubles, which sharply reduces consumer interest in them.

But the producers didn't stop there. Today on the market there are flash drives with a capacity of 256 GB and even 512 GB, which are essentially solid-state drives (SSD) enclosed in a compact case. Their cost is already so high that calling them ordinary flash drives is simply incorrect.

Communication speed

Despite the fact that volume does matter, one of the most important parameters of any drive is the speed of its data exchange with the device to which it is connected. In the case of flash drives, this characteristic is formed from three components: read speed, write speed and connection interface.

The read speed of all flash drives is always higher than the write speed. However, in some cases the difference can be very large. Therefore, before choosing a USB drive, it is better to decide how it will be used. If the information on it is rarely updated, then of course you can turn a blind eye to the recording speed. In the most budget models maximum speed Read speeds typically range from 10 to 15 MB/s, and write speeds range from 3 to 8 MB/s. This option is best chosen if the flash drive is intended for exchanging or transferring small files, such as documents.

But a flash drive with read speeds above 20-25 MB/s and write speeds above 10-15 MB/s can be called not very expensive, but at the same time universal solution, which is suitable for any task. There are flash drives with more attractive speed characteristics that make working with them a real pleasure. True, the price for such products is set accordingly.

As a rule, the maximum speed indicators affect the flash drive connection interface, which can be of two types - USB 2.0 and USB 3.0. In the first case (2.0) we are dealing with a maximum throughput of 480 Mbit/s. Thus, the maximum read or write speed of a USB2.0 flash drive cannot exceed 60 MB/s. In practice, manufacturers do not strive to reach this ceiling and provide their products with speeds barely exceeding 30 Mb/s.

As for the USB 3.0 interface, here throughput reaches up to 5 Gbps, which makes it possible to transfer data at speeds of 640 Mbps. Of course, for flash drives this is an exorbitant figure. However, even if we do not take into account devices with a capacity of 256 and 512 GB, some solutions already offer users read speeds of over 220 MB/s, and storage speeds of over 130 MB/s.

At the same time, the presence of a USB 3.0 interface in a flash drive does not guarantee that it will have high speed characteristics. Buying a USB 3.0 flash drive is most advisable if the drive has read/write speeds above 60 MB/s. If this is not the case, then a flash drive with a USB 2.0 interface may be a better purchase, both in terms of price and its characteristics. So in some situations there is no point in overpaying for a newfangled interface.

And one last point. It is important to understand that a flash drive with a USB 3.0 connector must be inserted into the device also into a USB 3.0 connector to realize its full speed potential. If your equipment does not have these, then you should again think about the advisability of purchasing a drive with such an interface.

Designer design

In the classic version, the flash drive looks like an elongated rectangle or a flattened cylinder, 5 to 8 cm long, with a removable cap that covers the USB connector. However, modern flash drives can come in a wide variety of shapes and sizes, as well as ways to protect the connector.

IN general case, flash drives can be divided into four groups based on the type of connectors:

Classic . The connector is closed with a cap. A good and reliable option. The only inconvenience is the possibility of losing the cap.

With retractable connector . They have one common disease. Over time, the mechanism that secures the connector becomes loose, which makes it much more difficult to install the flash drive into the end device.

With swivel mechanism . A fairly reliable option, in addition to giving the flash drive an original look.

With open connector . A practical and reliable option. The main disadvantage here is the possibility of contamination of the connector and moisture getting on it.

Another important external quality of a flash drive is the material from which it is made. It must be selected taking into account the frequency of use and degree careful attitude To her. The housings of these devices come in plastic, metal and rubberized types. Plastic cases can be called the most unreliable. This is especially true for flash drives with a retractable connector. Flash drives with metal casings are reliable and often look solid. Although to some their weight may seem excessive. As for rubberized cases, they are designed to create optimal conditions that resist impacts, shocks and prevent moisture from getting inside this technical device.

Now it has become fashionable to make souvenir flash drives whose bodies have a non-standard appearance, for example, in the form of some figures or various items everyday life. But all this “beauty” may backfire on you, since there is a possibility that in most cases you will not be able to use such a USB drive due to the dimensions of its case. Please note that when you buy a flash drive that is irregularly shaped or thick, it may simply not fit next to other devices installed in adjacent USB connectors.

Secondary functionsUSB- drives

We have looked at the main parameters for choosing drives, now let's move on to considering the auxiliary functions of these devices. In order to expand the sales market and increase the popularity of their products, some manufacturers are trying to provide flash drives with additional capabilities. Thus, a device activity indicator can be integrated into modern USB drives, which will make it possible to show the period of safe removal of the drive from the USB port, an electronic clock, and even a flashlight. There may be a function that provides protection against data overwriting and the possibility of hardware encryption of information. You can also find a drive with a built-in fingerprint scanner or card reader.

By the way, immediately after purchasing a new drive, do not rush to format it, as it may contain useful auxiliary software. These can be formatting utilities or applications for organizing data backup.

Conclusion

So, now you know the basic parameters, according to which you can now independently select a USB drive for certain purposes. The only thing we did not mention in this material is the manufacturers of these devices. In fact, there are many of them, and even a lot, especially if you take into account the many small unknown Chinese manufacturers united under the common name NONAME.

However, in conclusion we will name several leading players in this market, so that it will be easier for you to navigate among the numerous foreign names. The most widely represented and promoted companies on the Russian market are TRANSCEND, KINGSTON, SANDISK and SILICON POWER. No less popular are the products of A-DATA, CORSAIR, KINGMAX, VERBATIM, EMTEC, SMART BUY and some others. But in any case, when purchasing, first of all, be guided by technical characteristics And external parameters flash drives if you don’t want to ruin your mood and get a product under a big name that will not meet your expectations.