On the communication mechanism of "10" smartphone of cottage phone and Android

In the previous chapter, we said that the smart phone = = computer + mobile network card, this formulation is relatively rough, more accurate formulation should be, the hardware structure of the smartphone is divided into the application processor AP, and baseband processor BP two parts. Although the AP part of the function is basically similar to the computer motherboard, but the hardware structure is very different, the difference is reflected in the CPU choice, as well as the entire motherboard layout connection.

BP is responsible for the implementation of all communications software, its hardware structure, is not as simple as a network card. Baseband processor BP implementation, there are three ways.

1. Discrete devices (discrete components).

The BP part of the CPU, memory, power management, Wireless transceiver, power amplifier and so on, as a bulk device assembly together, known as discrete devices. As shown in Figure 10.1, the BP portion of the Palm pre is used as a discrete device [1]. Interestingly, the Palm pre has assembled the BP and AP parts separately on different boards. This is different from the Moto Droid and iphone 3GS, see Figure 9.6 in the previous chapter of the phone entity diagram, and figure 9.5 's logical structure diagram. The Moto Droid assembles the components that are logically part of BP, as well as the devices belonging to the AP, on the same board. And the iphone 3GS, although the AP and BP devices are assembled on the same circuit board, but isolated into different shielding areas.

The assembly of different discrete devices will have a certain effect on heat dissipation, vibration, weight and appearance. Each vendor's focus on these factors is different, leading to the choice of different assembly methods.

Figure 10.1 Palm Pre teardown and Analysis [1].
Courtesy Http://farm5.static.flickr.com/4030/4359122164_0f0e8be100_b.jpg

2. BP module.

The closest way to the NIC is the BP module. It is convenient to use the BP module. When designing the circuit board, the corresponding interface is designed, and in most cases it is the miniPCI interface. In the manufacturing, only the purchase of the complete BP module, the corresponding interface can be inserted. This is convenient, but at the cost of convenience, the 3G BP module is typically priced at more than $100. Therefore, familiar with the internal structure of BP, technology accumulation of thick mobile phone manufacturers, most do not use the BP module, but the choice of low cost, but the technical difficulty of the discrete device mode.

However, for other mobile devices, such as e-books (EBook), it is more important than cost to take the time to enter the market as a new product. And as a ofspecialty of the trial stage, the sales expectations are not high. In addition, Ebook's money-making is about selling content, not the device itself. Perhaps considering these three factors, Amazon's ebook, the Kindle 1&2,barns&noble ebook, the Nook, uses BP modules to address the need for mobile internet access [2,3,4].

Amazon Kindle 2 has two versions, and the U.S. domestic version uses the E725 miniPCI module from Novatel. The international edition uses the Anydata dtp600w miniPCI module. Since all two modules are MINIPCI interfaces, they can be easily interchanged.

In Figure 10.2, the photo on the left of the top row is the look of Amazon Kindle 2 International. The picture on the upper row middle and the right side of the top row is when you open the back cover and see the appearance of the Anydata dtp600w BP module. The picture on the left of the bottom row is the disassembly of the BP module, see the internal physical photos, the logical diagram of the right side of the next row, is the Kindle 2 International version of the logical structure diagram, the red line identified part of the BP module is included in the component.

Figure 10.2 The Amazon Kindle 2 and its BP module [3,5].
Courtesy Http://farm5.static.flickr.com/4007/4364813490_3c6c69de64_o.png

3. SoC (System on Chip) AP+BP two in-chip.

Both the AP part and the BP part are separated by the AT command, either in the case of the discrete device mentioned earlier or in the BP module, [6]. When you make a call, the AP controls BP through the AT command, and when there is a call, BP notifies the AP via the AT command.

Early mobile phone, AP and BP physical connection, through the serial port (UART) to achieve, not only need the serial port, but also usually need a universal input and output control line (General Purpose INPUT/OUTPU, GPIO), to coordinate the power management between AP and BP and so on. When the phone is idle, both the AP and the BP part are asleep in order to save power. When making a call, the AP wakes up BP via a gpio and sends the AT command through the serial port to BP. When there is an incoming call, BP also wakes the AP via a gpio, and then sends the AT command via the serial port, notifying the AP to start ringing, to switch the phone interface, and so on.

Obviously, using the serial port (UART), GPIO, plus at command to coordinate the work of AP and BP, the efficiency is not too high. Although later mobile phones, using USB or SPI to replace the UART, efficiency has improved, but overall, AP and BP coordination, is still the entire mobile phone productivity bottleneck.

AP and BP each have a separate CPU chip, not only the communication efficiency between each other is poor, and the cost of acquiring a chip is high, occupy the cell phone circuit board area is large, while also power consumption. To overcome these shortcomings, the advent of SOC two-in-one chip is the trend, the difficulty is that the SOC chip design and manufacturing difficult [7]. For example, within the SOC, the AP and BP divisions remain clear, and the communication between the two typically relies on memory sharing. However, the technical difficulty of implementing memory sharing is much more complex than the AT command (8).

GPhone is a mobile phone with a built-in Google Android operating system. [10] For example, the October 2008-listed g1,2009 April G2, and January 2010 's freshly-baked nexus one[9], are HTC's products. Nexus One's CPU configuration is Qualcomm's QSD8250 1GHz chip [11], while G1 and G2 use Qualcomm's MSM7200 series chips, see figure 10.3[12].

Figure 10.3 HTC Android G1 teardown and Analysis [12].
Courtesy Http://farm5.static.flickr.com/4004/4358377359_03420dd1a7_o.png

The Qualcomm QSD8250 used by GPhone Nexus one, as well as G2 's Qualcomm chips used by G1 and MSM7200, are SOC chips that are both AP and BP two. Take MSM7200 chip For example, its AP part built two CPU cores, one is ARM11, the other is the DSP dedicated core QDSP5,BP Part also has two CPU cores, respectively ARM926 and DSP dedicated kernel QDSP4, see figure 10.4 left, and references [13].

Qualcomm's MSM7XXX series AP+BP SOC chips were listed in 2006 or so. In fact, as early as 2001, TI launched the AP+BP SOC chip, OMAP710. Since then, TI has launched the omap730,733,750,850,1030, 1035 Soc chip. For the internal structure of TI OMAP710 and OMAP850, see Figure 10.4 on the right. [14] from OMAP710 to OMAP850, the speed increased, memory increased, and functionality increased.

[15] Qualcomm's SOC Chip family, however, features an active support for the Android phone operating system, which is intended to be similar to the Intel-bound Windows computer operating system, which is allied to form the Wintel hardware and software symbiosis, which occupies the dominance of the PC domain. Qualcomm is able to ally with Google, the formation of MSM and Android hardware and software symbiosis, to seek the supremacy of the field of smartphones, we will wait and see.

Figure 10.4 Qualcomm MSM vs TI OMAP [10,11].
Courtesy Http://farm5.static.flickr.com/4054/4358401341_5b51b0037f_o.png

To sum up, the BP part of a smartphone is functionally equivalent to a functional cell phone, so in fact the smartphone is equivalent to the function phone (BP) plus the new AP part. BP's approach has three different ways, 1. Discrete device, which is an early smartphoneBPPart of the main implementation, such as the Intel PXA series chip CPU-based phones. Now Iphone,palmpre, the Moto droid also inherits the structure of the discrete device. 2. BP module, this method is simple to use, but at a higher cost. Non-mobile mobile devices, commonly used in this design. 3. AP+BP two-in-one SOC chip, the most technically difficult, but also the highest profit margins, is the most commonly used in mobile phone BP implementation, such as the HTC phone with TI's SOC chip, using the Qualcomm SOC chip, and Nokia smartphones mostly use Ti Soc.

All-in-one AP and BP, using the high profits of SOC chips to get the maximum profit on each handset, is the dream of every chip manufacturer. because of the high cost of SOC chip development, in order to maintain economic efficiency, chip manufacturers must achieve high-volume production. So chip makers are putting a lot of effort into helping handset makers design their own chip-based handsets. From the standpoint of handset manufacturers, because of the strong support of chip manufacturers, the use of SOC chips can reduce their own development difficulties, shorten the development cycle, increase market opportunities. Because of this, the SOC becomes the mainstream of the hardware structure of the current phone.

2G to 3G,AP+BP two-in-a-chip SOC competition is extremely fierce. There are Ti,adi, Siemens, Sagem, Nxp,marvell,qualcomm and Infineon (Infineon) and so on, [16] who are more likely to win and become leaders in the industry? Small and medium-sized manufacturers chip manufacturers such as Spreadtrum and MTK and mobile phone equipment manufacturers Htc,motorola and so on, whether it can be a hero, participate in division of labor, and constantly grow their own? These questions are left for subsequent chapters to discuss.


Reference,

[1] Palm Pre with WebOS teardown and analysis. (http://www.phonewreck.com/2009/06/07/palm-pre-teardown-and-analysis-review-coming-soon/)
[2] Amazon Kindle1 teardown and analysis. (http://www.rapidrepair.com/guides/amazonkindleguide/amazon-kindle-Take-Apart-Guide.htm)
[3] Amazon Kindle2 teardown and analysis. (http://www.phonewreck.com/2010/01/27/amazon-kindle-2-global-wireless-teardownin-depth-analysis/)
[4] barns&noble Nook teardown and analysis. (http://androidandme.com/2009/12/hacks/nook-rooted-how-to-and-teardown-pics/)
[5] Amazon Kindle2 network card teardown. (HTTP://WWW.IFIXIT.COM/TEARDOWN/KINDLE-2/624/1)
[6] Introduction to AT commands. (http://en.wikipedia.org/wiki/AT_commands)
[7] Design an optimal wireless SoC. (http://www.eetimes.com/showArticle.jhtml?articleID=49900397)
[8] Solving SoC shared memory resource challenges. (http://www.design-reuse.com/articles/5816/solving-soc-shared-memory-resource-challenges.html)
[9] Google Nexus one reviews. (http://chinese.engadget.com/2010/01/05/nexus-one-review/)
[Ten] A List of Android Devices. (http://en.wikipedia.org/wiki/List_of_Android_devices)
[One] Google Nexus one teardown and analysis. (HTTP://WWW.IFIXIT.COM/TEARDOWN/NEXUS-ONE-TEARDOWN/1654/2)
HTC T1 teardown and analysis. (http://www.phonewreck.com/2008/12/09/t-mobile-g1-review-and-teardown/)
[] Android OS with Qualcomm MSM7200 chip. (http://mobile.onegreen.org/Article/HTML/15203.html)
[] Ti's OMAP750 and OMAP850 two CPU comparison. (http://hi.baidu.com/sl1987/blog/item/0afb5a663d663f23ab184c1a.html)
[] The silicon behind Android. (Http://www.engadget.com/2009/10/14/core-values-the-silicon-behind-android/)

On the communication mechanism of "10" smartphone of cottage phone and Android