USB TYPEC Interface Standard--The Last King of the Cable Interface Age
Release time：2019-06-25author：adminfrequency：101次
In March 2015, Apple released a new MacBook and adopted USB Type-C, which triggered a heated debate in the industry. Apple has never abandoned its closed system before. This means that TYPEC is expected to unify the wired interfaces of all mobile phones, tablets, PCs and other devices and form a unification before the end of the wired era. Now parse this USB Type-C from the hardware point of view, by the way.
microUSB：7.4mmx2.35mm
lightning：7.5mmx2.5mm
So I can't see the advantage of USB Type-C on handheld devices in terms of size. Speed, however, depends only on whether video transmission is needed.
It can be seen that data transmission mainly includes TX/RX two groups of differential signals, CC1 and CC2 are two key pins, which play a lot of roles:
Don't look at USB Type-C as if it can support up to 20V/5A. In fact, it needs USB PD, while supporting USB PD requires additional PD chips. So don't assume that a USB Type-C interface can support 20V/5A.
DFP is the master and UFP is the slave. In addition to DFP, UFP, there is also a DRP, DRP can do DFP can also do UFP. When DPR receives UFP, DRP is converted to DFP. When DRP is connected to DFP, DRP is converted to UFP. When two DRPs are joined together, either one is DFP and the other is UFP.
CC in DFP
Pin has pull-up resistance Rp and UFP has pull-down resistance Rd. When not connected, the VBUS of DFP has no output. After connection, CC pin is connected, and CC of DFP is connected.
When both CC pins are connected with pull-down resistor <=Ra, DFP enters the mode of audio accessories, both left and right channels and Mic are available, as shown above.
Small size, support positive and negative interpolation, fast speed (10Gb). This small is for the USB interface on previous computers. Actually, it's a little bigger than the microUSB on Android.
Characteristic
USB Type-C：8.3mmx2.5mmmicroUSB：7.4mmx2.35mm
lightning：7.5mmx2.5mm
So I can't see the advantage of USB Type-C on handheld devices in terms of size. Speed, however, depends only on whether video transmission is needed.
Pin definition
It can be seen that data transmission mainly includes TX/RX two groups of differential signals, CC1 and CC2 are two key pins, which play a lot of roles:
Detect connections, distinguish positive from negative, and distinguish between DFP and UFP, that is, master and slave.
Configure Vbus, there are two modes of USB Type-C and USB Power Delivery
Configure Vconn. When there is a chip in the cable, one CC transmits the signal and one CC becomes a power supply Vconn.
Configuration of other modes, such as access to audio accessories, dp, PCIe
There are four power sources and four ground sources, which is why 100 W can be supported.
Don't look at USB Type-C as if it can support up to 20V/5A. In fact, it needs USB PD, while supporting USB PD requires additional PD chips. So don't assume that a USB Type-C interface can support 20V/5A.
Of course, there should be integrated chips in the future.
Auxiliary signals sub1 and sub2 (Side band use) are used only in certain transmission modes.
D + and D - are compatible with pre-USB standards.
Here, USB 3.0 has only one set of RX/TX, and its speed is 5GB. USB Type-C uses two sets to ensure that both sides can be plugged in. But in fact, only one set of RX/TX is used for data transmission, and the speed has reached 10GB. If the protocol is upgraded later, the two groups will be 20 GB like DisplayPort.
Workflow
DFP is the master and UFP is the slave. In addition to DFP, UFP, there is also a DRP, DRP can do DFP can also do UFP. When DPR receives UFP, DRP is converted to DFP. When DRP is connected to DFP, DRP is converted to UFP. When two DRPs are joined together, either one is DFP and the other is UFP.
CC in DFP
Pin has pull-up resistance Rp and UFP has pull-down resistance Rd. When not connected, the VBUS of DFP has no output. After connection, CC pin is connected, and CC of DFP is connected.
Pin detects the pull-down resistance Rd of UFP, indicating that when connected, DFP opens the Vbus power switch and outputs power to UFP. Which CC pin (CC1, CC2) detects the pull-down resistance determines the direction of the interface insertion and switches RX/TX by the way.
Resistance Rd = 5.1k, resistance Rp is an uncertain value. According to the previous figure, we can see that there are several power supply modes of USB Type-C. What is the basis for screening? Depending on the value of Rp, the value of Rp is different, the voltage detected by CC pin is different, and then control which power supply mode the DFP terminal performs.
It should be noted that the two CCs are drawn in the picture above. In fact, there is only one CC line in the cables without chips.
The cable containing the chip is not two CC wires, but a cc, a Vconn, which is used to power the chip in the cable (3.3V or 5V). At this time, there is no pull-down resistance Rd at the CC end, but the pull-down resistance Ra, 800-1200 Euros.
When both CC pins are connected with pull-down resistor <=Ra, DFP enters the mode of audio accessories, both left and right channels and Mic are available, as shown above.
USB Type-C and DisplayPort, PCIE
USB PDs are BMC coded signals, while the previous USB is FSK, so there is incompatibility, I do not know whether there are products that can be converted on the market at present.
USB PDs are transmitted on CC pin. PDs have a function of VDM (Vendor defined message), which defines device-side ID. When reading devices supporting DP or PCIe, DFP enters alternate mode.
If DFP recognizes that device is DP, it switches MUX/Configuration Switch and changes the Type-C USB3.1 signal footer to transmit DP signal. AUX assistance is transmitted from SBU1 and SUB2 of Type-C. HPD is a test foot, similar to the C C, so it is shared.
DP has four groups of differential signals of lane 0-3 and Type-C has four groups of differential signals of RX/TX1-2, so it is no problem to replace them completely. In the alternative mode of DP protocol, USB signal and DP signal can be transmitted simultaneously, RX/TX1 can transmit USB data, RX/TX2 can be replaced by lane0, and two sets of data transmission can be supported to 4K at this time.
If DFP recognizes that device is DP, it switches MUX/Configuration Switch and changes the Type-C USB3.1 signal footer to transmit PCIe signal. Similarly, PCIe uses RX/TX2 and SBU1, SUB2 to transmit data, and RX/TX1 to transmit USB data.
The advantage is that one interface uses two devices at the same time, of course, the conversion line can be achieved without any chip.
Summary
USB Type-C terminates the long-standing defect of USB plug-in and plug-in, saves people a lot of time, change direction at least 2s, plug-in USB once a day according to the global billion people, 50% probability, a total of 277,000 hours, about 31 years, too terrible.
One interface has three kinds of audio and video data, and its volume is still small. It can be predicted that Android can be changed to USB Type-C interface in the future. If only USB 2.0 is needed, only the cables need to be redone, and some functions need to be added with interface chips, so the cost can be completely neglected.
As for Thunderbolt, lightning, what should we do? Flowers blossom is a colorful world. Shenzhen Ledery Technology Co., Ltd. has taken the lead in introducing TYPEC adapter, mobile power supply and switching solution in the industry, which is fully prepared for supporting TYPEC in an all-round way.
