Cheap button phones today

In recent years, smartphones cover an increasingly large part of the mobile phone market. But, looking at the range of dns-shop.ru, you can find a couple of hundred models of buttons. Interesting and prices for them - within 8-10 dollars you can buy a two-phone phone with a memory card, player, Bluetooth, radio, and, of course, a conference connection, which is provided by a single speaker turned away from your ear. In general, an excellent artifact in case you, for once, decide to bludgeon, go to the army, prison, or a hot place.

Remembering the abundance of firmware for the null buttons, I began to look for communities to read how it all works and what can be made of such a beast. Then I was very surprised to see that there was almost no information. Therefore, you should not be surprised that under the cut it will be a bit.

Modern cheap buttons are literally a phone on a chip. This is a special SoC (System on Chip), honed under a typical mobile phone. It has a central processor with RAM, peripherals in the form of a communication coprocessor, a Bluetooth module, a module for a camera with a couple of megapixels, etc. All of these SoCs have an ARM architecture, less commonly MIPS and plus or minus the same capabilities and peripherals. Unification has reached such limits that all these phones are basically no different than the case.

Here is the example of Mediatek products implemented in MT 62 ** series chips, which are approximately 8x8 mm in size:

• Bluetooth transceiver
• FM radio receiver
• GSM / GPRS transceiver
• controller camera resolution up to 640x480
• display controller up to 320x240 resolution
• hardware codecs for JPEG, MJPEG, GIF, PNG, AMR, AAC, H.264, MPEG-4
• 2D accelerator for typical operations such as rotation, scaling, layer blending, font and sprite rendering
• 1.2 watt audio amplifier
• interfaces for USB 1.1 and SDIO, the latter is also used to work with microSD
• keyboard controller up to 25 buttons
• controller for charging Li-Ion batteries
• java application accelerator

There are several brands that make these SoCs. Here is a table that gives an idea of ​​the hardware stuffing of most cheap buttons released in recent years:

All chips support at the hardware level several SIM-cards, up to 4. Some support Java hardware acceleration, but because of licensing issues, you will not find Java ME in any of the Chinese phones. For MTK phones, you can create applications in the same style as for the JVM, only this is called MRE. Technically, the Internet is in every phone, even the cheapest, since the GPRS modem and the interface to it are already in the chip. In practice, however, only if there is at least one program supporting it on the phone.

On Spreadtrum chips you can find fakes for expensive android phones. This is when a person approaches you on the street and offers to buy, for example, Samsung Galaxy 4 at half price, because you really need money, brother. Inside, there will be a fake for an android in which there is not even always WiFi.

According to fragmentary information, all these push-button telephones work under the control of Nucleus OS from the company Mentor Graphics. This is an operating system on the micronuclear architecture, designed for embedded devices. In the case of MTK devices, MTK OS takes place; this is the same Nucleus, but licensed and slightly modified. Development is conducted in C and C ++. If you compare the feelings, then all modern mobile OS buttons are analogous to the Nokia Series 30 , which was on the cheapest phones. And this is despite the fact that more chips can be squeezed out of modern chips, while OS Nokiea Series 30+ and Nokia Series 40 themselves work on the chips described above.

Poking around in these phones is not easy. Firstly, there is no free documentation on chips, it is given only for money when buying a batch of chips themselves. Specifications on the characteristics of the chip should be asked in the sales department, because they are usually not spread on sites. The only way today, if you don’t know Chinese, is to merge the firmware through the programmer and play with the disassembler. According to rumors there is nothing encrypted and obfustsiruyutsya.

As for the community, it is not. All switched to more modern mobile OS. There is no information from repairmen either. The cheapness of the phones on the described platforms has played a cruel joke with them - it is simply unprofitable to repair them.

The only thing some craftsmen do is, if possible, merge firmware through programmers like Miracle Box. So that later it would be possible to upload them to the same phones that will come to the service with software glitches.

But honestly, it is strange. Such devices are sold in millions of copies, the platform is much more unified than in the middle of zero. But there is no community, no documentation, nothing. In Runet, there is a drain on tools for working with MTK chips a decade old and some documentation, but that's about all.

Since I am very far from the stated topic, I ask you to correct the factual errors and to make additions whenever possible. If you do not have an account in Habré, then in my profile there is a mail where you can send what you can tell and I will publish it here (if you want with attribution).