"In just 20 years, technological innovation has brought earth shaking changes to people's lives. It can be said that it has experienced a whole cycle from living room TV to computer desktop, then to mobile phone, and now back to living room TV. However, at this time, the concept of TV is not so simple. We give it a new term -" smart TV ". What is smart TV? Encyclopedia is defined as a new TV product with an open platform, an operating system (currently commonly equipped with Android system), the ability to install and uninstall various application software, and the ability to continuously expand and upgrade functions.
However, from a higher level, smart TV should belong to an intelligent system. Even ordinary TV can join the ranks of smart TV after external expansion and upgrading. The intelligent system is not aimed at the TV itself, but the content of service. Therefore, major manufacturers have launched TV boxes and TV sticks, which are based on their own content service support. As long as they are simply set up and connected, they can form an intelligent TV system with ordinary TV. Moreover, from the perspective of upgrade cost, it is more acceptable and likable. Speaking of this, I think I can invite today's protagonist - chromecast.
chromecast
Chormecast is a product developed by Google, one of the most technologically innovative companies. It has a built-in simplified Chrome OS system. It is mainly used to output the TV as the second screen of mobile devices such as mobile phones, tablets or computers, and does not affect the simultaneous use of other programs or app applications on these devices.
Chromecast accessories
HDMI 1080p output
2.4GHz WiFi 802.11 b/g/n
Maximum output resolution 1080p
USB power supply
Compatible with a variety of devices, including Android and IOS devices
The chromecast box includes a chromecast, a 5V DC adapter, a micro USB power supply cable, an extension cable of standard HDMI interface, a chromecast product description, and a considerate use guide on the opened box cover.
Chromecast
Chromecast looks like a fake MP3, 72 * 35mm. Its peripherals include a standard HDMI interface, micro USB interface and a reset button. It is about the same size as Baidu video stick, link play and other TV sticks on the market, but its working principle is different from these products. For example, baidu video stick, link play and other products are established based on DLNA protocol, So as to share the content of mobile devices, and chromecast receives a group of URLs from mobile phones or computers, and then directly pulls the information from the cloud for playback.
Chromecast plays cloud content directly
Chromecast trial
We deepen our understanding through a simple trial. Follow the steps in the user's Guide to connect chromecast to your TV. Plug the TV station into the HDMI connector of chromecast.
Chromecast on TV
Then download the chromecast app through the mobile device in the Google play mall to set up the wireless network of chromecast.
Download the chromecast app from your mobile device for settings
After setting, the prompt ready to cast will appear on the TV screen, and you can see the corresponding wireless network connected
chromecast ready on TV
Then it's simple. Just install a chromecast extension plug-in on your browser. After that, click the plug-in icon to send the URL of the corresponding web page to the chromecast you plug in on the TV, and then chromecast will grab the content in the cloud for playback.
Most importantly, you can use other programs or app applications at the same time when using chromecast. As long as you don't turn off the tab of cast, other operations will have no impact. This really meets the actual needs of users, and its operation process is quite simple.
However, for Chinese mainland users, chromecast is almost nothing, unless you just want to share what is on the web page. Cast plugins decide that it can not share the local content on the TV. As for the content on the Internet, chromecast supported video applications or websites do not support Chinese mainland browsing:
YouTube app and YouTube.com
Netflix app and Netflix.com
Google Play Movies & TV
Google Play Music
Hulu Plus
Pandora
HBOGo
Computer mobile phone computer principle or mobile device can access these contents through the wall. But think about the working principle of Chromecast, it is not browsing with your mobile phone or computer at all. So Chinese mainland users can not feel the visual feast brought by chromecast so far.
Through the trial of chromecast, we can feel Google's persistence in living room entertainment and lead people back to TV in a simpler way. Chromecast is easy to use and operate, coupled with the $35 price close to the people and Google's brand influence, it is difficult to be rejected by the market.
Disassembling chromecast
After seeing the trial of chromecast, I believe that the estimate for Chinese mainland users is a big blow. But never mind, this does not hinder us from further analyzing this gadget.
Remove the chromecast to expose the shield of 66-6c
The plastic shell is not fixed with any screws, but simply fastened together. However, the most difficult step in the whole disassembly process is to remove the shell, and it can no longer be fastened after removal. It should be fixed with a small amount of glue
Both sides of the square are well covered by shielding cover, and well grounded
Next, it's easier. On the other side is a 66-4c shield and a heat dissipation aluminum block is embedded at the bottom of the shell. It's all disassembled
All disassembled
Chromecast is injected with quite a lot of heat dissipation silicone grease, which shows that its working temperature should be quite high
Chromecast memory side
One side of the chromecast is the memory part, including Meguiar mt29f16g08maa 2GB NAND flash memory and d9pxv 512MB ddr3l SDRAM. The configuration is general, but The low voltage of ddr3l memory ensures the power consumption of chromecat. In addition, there is a special place where a 17pin pad is reserved. Through the comparison of many disassembly drawings, it is found that this place originally has an interface, including at least one UART interface with Rx, TX and GND signal lines. The output log can be seen from the initialization process of boot.
It can be concluded that this is an early debugging interface, which has been cancelled in the current version.
Main function part of chromecast
Here comes the play. The other side of chromecast is the implementation of the main functions. The "IC" near the 5V micro USB interface side is azurewave aw-nh387, which integrates 802.11b/g/n, Bluetooth, FM and other functions. Specifically, it should be an SOC module, which is composed of Marvell's highly integrated WLAN & Bluetooth chip 88w8787 and other components SOC.
SOC----AzureWave AW-NH387
Azurewave's aw-nh387 SOC integration scheme truly achieves the extreme of the product. Any manufacturer using aw-nh387 chip can form a set of wireless solutions including FM, WiFi and Bluetooth by adding power supply, antenna and microcontroller to the periphery, which basically realizes no technical threshold in hardware.
The chipset near the HDMI interface of chromcast is the 88de3005-a SOC scheme of Marvell, also known as armada 1500 mini, which is a set of HD video and audio decoding SOC scheme based on its sheeva processor core, supporting 1080p. This is a multi screen interactive home entertainment scheme specially created by Marvell for products like chromecast. It has been derived and optimized based on its well-known armada1500 product series to support low-power applications.
So far, we can basically infer the hardware implementation scheme of chromecast
Hardware principle of chromecast
From chromecast, we can see that Google does not pursue high configuration like its mobile phone, but from reality, in line with the principle of sufficiency, it adopts an extremely simple whole set of solutions, which basically has no threshold for implementation. Any qualified design house can complete it, and the significance of Google's launch of chromecast does not lie in hardware, It is a thinking of living room entertainment to everyone -- a living room entertainment carrying cloud information.
Compare similar products on the market
At present, there are many small boxes with HD playback function, and Baidu will also launch its Baidu shadow stick. Here we use a linkplay of Shenzhen Lianyun technology and chromecast for comparison. The content of the mobile device is also transmitted to the TV through wireless sharing. However, it can share wirelessly through the DLNA protocol of Android devices or the airplay protocol of IOS devices. The specific use method can be referred to here. We will focus on the principle of linkplay.
Linkplay is slightly larger than chromecast, 87 * 33mm
Linkplay vs. chromecast size
However, compared with chromecast, the disassembly of linkplay is much easier. You can easily break the buckle with your fingers and divide the whole linkplay by three times and five times
Linkplay disassembled
First, let's take a look at the main function implementation of linkplay, including linkplay's core processing chip - map220 chip of apusone company, WiFi module rtl8188ctv and micron's 128M DDR3 SDRAM - mt41j128m16jt.
Linkplay main function side
Map220 is a mobile multimedia application processor that focuses on low power consumption and supports 1080p decoding. It is a product of wuquxin electronic technology, an emerging semiconductor company. There is little information. At present, the performance parameters of this chip are not clear, but from the actual experience, it is competent for the implementation of linkplay function.
Linkplay's WiFi module is based on Realtek's mature application scheme rtl8188ctv chip, supports 802.11 B / g / N protocol, and is powered by 3.3V voltage. The WiFi module can also be used as a wireless routing module, with a maximum transmission rate of 150Mbps. When designed and used, the wifi antenna needs 50 ohm impedance matching, and the output WiFi data is output through USB signal, The USB signal data output line needs 90 ohm differential signal impedance matching. At present, the quotation of this WiFi module on smart.com is only 12.5 yuan / piece, which is very low cost and easy to use.
Linkplay other side
The most intuitive feeling on the back of linkplay is very simple. There are no mysterious things. There is a micro USB interface, a reset button, and a 128MB NAND flash -- s34ml01g100tf100 provided by span company. There is nothing special about others.
Looking back on the board, we can basically summarize its application scheme
Linkplay hardware principle block diagram
Compared with the hardware scheme of linkplay, it is not difficult to find that the hardware principle is basically the same as that of chromecast, but there are many differences in software protocols. Chromecast directly obtains the cloud content through the URL data transmitted by the device, and linkplay directly plays the resources shared from the device or the network through DLNA protocol or airplay protocol.
After understanding the basic principles of the two devices, we will make a summary comparison between the two products:
Difference between chromecast and linkplay (click the picture to enlarge)
Summary
Through the trial and disassembly of chromecast and the comparison with linkplay, it is not difficult to find that chromecast should belong to an experimental product of Google, which is excellent but not perfect. Especially for domestic users, chromecast is like an ornament. Its original excellent functions such as youtube and Netflix have become chicken ribs, while linkplay, which seems to have no popularity, can well become a good product for domestic users to share videos and other functions. However, it can also be seen from the disassembly that there are considerable differences in workmanship between the two. Chromecast has far greater potential for hardware configuration and function upgrading than linkplay. From major manufacturers have joined the competition for the cake of living room entertainment, we can be sure that WiFi wireless audio and video products will definitely become the mainstream in the future, because it not only realizes the traditional wireless video transmission (such as 2.4G and Bluetooth) function, but also realizes the cloud playback of audio and video. We look forward to what kind of change chromecast will bring us.
reference material
Chromecast
Shenzhen Lianyun technology linkplay
Azurewave of Haihua Technology
Marvell Electronic Technology“
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