Upgrade or trickery? From USB PD 2.0 to 3.0

Publish Date:2016-10-27 | Hits: | 字号:



    As the emergence of the iPhone, only to smart phones really dominate the mobile phone market, Type-C port after the release, USB PD was officially entered the public view. In fact, USB PD 1.0 standards in July 2012 has been released. At that time, USB interface is the traditional TYPE-A and TYPE-B, all connection resources, have been VBUS, GND and DATA transmission line occupied. Thus, USB-IF played the idea of VBUS and GND, through a high-frequency carrier, the USB PD protocol communication data modulation to VBUS, the receiver from the VBUS signal isolation and demodulation.




 Figure 1 failed attempts - based on FSK modulation USB PD


    Have to say, this is a very good IDEA, because at that time, power line carrier technology in the rapid development of indoor low-voltage power line carrier technology, and even a great replacement for broadband network posture. Therefore, the application of this technology to the USB bus, seems to be smooth. However, the fact that this is a failed attempt, involving the PD signal and power and USB data integrity between the signal and other issues, the specific reasons will not repeat them.Time to August 2014, USB-IF breath issued a revolutionary TYPE-C 1.0 interface standard and USB PD2.0 standard, in order to achieve a dedicated communication line CC, the USB PD communication signal transmission.



Figure 2 USB PD and TYPE-C interface, the perfect combination - the use of CC-line BMC encoded transmission


    The two standards, released at the same time, complement each other and describe a grand picture of the cable interface revolution. To this end, Xiao Bian also wrote a year ago, entitled "The last line of the era of the king of the cable interface," the article, depicting the type-C interface to consumer electronics applications brought about revolutionary changes. USB PD allows the magic USB TYPE-C interface, not only has the traditional power, data transmission capacity, also has the audio and video transmission capabilities. Moreover, whether it is power, data, or audio and video transmission speed, than the traditional transmission line to be even better. So TYPE-C interface will undoubtedly monopolize the existing consumer electronics transmission interface market. Of course, do not rule out the future will appear with fiber as the transmission medium of the cable interface to further improve the transmission speed.


    From the technical point of view, USB PD2.0 is very fascinating, the entire standard is very open, providing power and data, audio and video transmission of the complete protocol framework, while leaving VDM, that is, custom data packet capabilities, Enterprises can carry out private protocol processing, battery management, firmware upgrades, private encryption and so on. It can be said is already a more perfect system. While the industry cheered, and try to digest, USB-IF organization at the end of 2015, launched the USB PD version 3.0, so that players shake the industry is not small. Let us take a look, this big revision, focus on what changed?


First, a more detailed description of the device's built-in battery characteristics is added


Second, the increase in the PD through the communication device software and hardware version identification and software updates


Third, digital certificates and digital signatures have been added


Figure 3 PD3.0 can access the details of the internal battery pack


    The first point of change, to connect the two sides, more clearly each other's power situation, so as to coordinate the power supply strategy of both sides. For the use of USB PD protocol set up low-voltage intelligent power supply network, is extremely important. Can coordinate the power supply topology in a variety of power conditions. For example, when the power grid emergency power supply processing strategies, coordination of power supply and home solar power plant power supply strategy to the grid reverse power supply strategy. Can make Power become more SMART.


Figure 4 USB PD3.0 support online upgrade


    The second point of software upgrades, you can make the device compatibility becomes more excellent, all TYPE-C vendors can put their latest firmware version released to the Internet, so that you can through the PC and mobile phones, non-networked Of the external accessories for a timely update. Just as Microsoft's win10 system to real-time online hardware driver problem. The internal firmware of the USB PD device also becomes part of the traditional hardware-driven resources.


Figure 5 PD3.0 defines the digital certificate function


    The third point of digital certificate function, it is estimated that the most important feature of the upgrade. You can make all TYPE-C products must obtain a digital certificate issued by a USB-IF organization using a private key to be unimpeded. Certificated products, it may not be other manufacturers TYPE-C products are acceptable. This feature has a very positive meaning, to avoid unqualified TYPE-C interface device, because of quality problems and damage the normal equipment. In enterprise information security applications, enterprises can also be issued by their own security certificate for non-enterprise internal USB devices can not access, which will be more secure than the existing USB encryption technology, because in the CC line through the completion of safety certification, The storage medium is physically isolated from the system. Of course, we also hope that USB-IF can really benefit the member companies, rather than Apple's MFI, as by providing authentication and digital certificates, in exchange for huge commercial interests.


Figure 6 USB PD 3.0 perfect compatibility 2.0 no hardware changes, product development do not hesitate


    For domestic manufacturers, the technology owned by technology, more important thing is to see how the product development route. To small series point of view, do not have too much attention to these upgrades. First of all, from the agreement on the PD2.0 is PD3.0 subset, that is, PD3.0 is a natural compatible pd2.0. Secondly, from the hardware level, PD3.0 and PD2.0 link layer and physical layer is fully compatible, that is, product upgrades, no hardware changes, only the need for online software upgrades. Therefore, both from the agreement itself or from a market strategy point of view, can be actively to the development of USB PD 2.0 products, to the necessary time to upgrade the firmware part to be compatible with PD3.0. Speaking of this problem, just to clarify the issue of MACBOOK2016 upgrade, in fact, APPLE this upgrade, and PD3.0 does not have any relationship, did not join the digital certificate of such things. But increased the PD2.0 protocol timing constraints, similar to the USB-IF compliance test. All non-compatible equipment, are their own products, do not mislead the industry manufacturers, that USB PD protocol is often updated, resulting in product compatibility is not good, TYPE-C market, such as Shen. In fact, all the market players, including VL, FRESCO, LDR have been or are joining the USB-IF, and to accept compliance test, but because of the different R & D focus, so the upgrade speed is not the same, LDR as the mainland manufacturers, Response speed is the fastest, MACBOOK2016 after the market within a month has been released on the agreement with the perfect compatibility of USB PD adapter chip LDR6021 and DOCKING chip LDR6023 upgrade.


Figure 7 LDR6023 and MACBOOK2016 with the perfect realization of Power_SWAP


    The chip manufacturers in Europe and the United States and Taiwan because R & D investment direction, has not yet launched a perfect solution version, and even maintained the error protocol version of macbook2015, has not done any changes.


    These are small series learning USB PD3.0 standard, some rough insights, personal view from USB PD2.0 to USBPD3.0 is a very constructive significance of the progress of the USB-IF point praise. Of course, interpretation is inevitable fallacies, the right to initiate. Hope that we work together, based on TYPE-C port application of more innovation.


    C-FORCE, is specialized in USB TYPE-C interface and USB PD protocol technology research group, follow-up will be launched "USB PD-based fast charging method", "domestic machine manufacturers how to Fun TYPE-C" -related Papers, welcome attention.LDR-PD02 LDR-PD01


    If you are interested in this article, please feel free to join our C-FORCE micro-signal: 13510191269